Conservation status and the use of Irrawaddy dolphins as a flagship species for climate adaptation in the Peam Krasop Wildlife Sanctuary, Cambodia

Transcription

1 Conservation status and the use of Irrawaddy dolphins as a flagship species for climate adaptation in the Peam Krasop Wildlife Sanctuary, Cambodia Building Resilience to Climate Change Impacts in Coastal Southeast Asia (BCR) Brian Smith, Sun Kong and Lieng Saroeun INTERNATIONAL UNION FOR CONSERVATION OF NATURE

2 The designation of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN or the European Union concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in this publication do not necessarily reflect those of IUCN, the European Union or any other participating organizations. This publication has been made possible by funding from the European Union. Published by: IUCN Asia in Bangkok, Thailand Copyright: 2014 IUCN, International Union for Conservation of Nature and Natural Resources Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged. Ria Reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder. Citation: Smith, B., Kong, S., and Saroeun, L. (2014). Conservation status and the use of Irrawaddy dolphins as a flagship species for climate adaptation in the Peam Krasop Wildlife Sanctuary, Cambodia. Thailand: IUCN. 80pp. Cover photo: Dolphins in Koh Kong Province, Cambodia IUCN Cambodia/Sun Kong Layout by: Ria Sen Produced by: IUCN Southeast Asia Group Available from: IUCN Asia Regional Office 63 Soi Prompong, Sukhumvit 39, Wattana Bangkok, Thailand Tel: IUCN Cambodia #6B, St. 368, Boeng Keng Kang III, Chamkarmon, PO Box 1504, Phnom Penh, Cambodia Tel:

3 Acknowledgements We would like to express our gratitude to Dr. Robert Mather, Head of Southeast Asia Group, IUCN, for initiating the dolphin assessment in the Peam Krasop Wildlife Sanctuary (PKWS) and adjacent coastal waters and mobilizing the survey team. Special thanks are given to H.E. Say Socheat, Deputy of Koh Kong Province, as well as other local authorities in Koh Kong who provided permission for us to bring dolphin survey equipment from Thailand. We also thank the Fisheries Administration for kindly supporting administrative work related to the project and offering the assistance of one of their officers to participate in the dolphin survey. We would like give our deep thanks to Mr. Kong Kimsreng, Senior Program Officer, IUCN Cambodia, for consistently providing helpful ideas and technical support. We are also grateful to Mr. Sorn Pheakdey for providing GIS assistance and producing the survey maps, and Mr. Lou Vanny for assistance in the field and advice on recommendations. Sincere thanks are given to IUCN s Building Coastal Resilience network in the Kong Kong Province, including representatives from the Department of Environment, Fisheries Administration, PKWS and local communities who participated in the dolphin survey. Finally, we would like to gratefully acknowledge funding support from the European Union Project for the Building Coastal Resilience to Climate Change Impacts in Southeast Asia Project. 2

4 Foreword Building Resilience to Climate Change in Coastal Southeast Asia (BCR) is a four year EUfunded project working with communities and local government agencies in 8 provinces of Thailand, Cambodia and Viet Nam along the coastline between Bangkok and Ho Chi Minh City. Initial desk study reviews of likely climate change impacts on locally and nationally important species and habitats identified the coastal populations of the Irrawaddy dolphin in Trat Province of Thailand, and Koh Kong Province of Cambodia as a species of particular interest to the project. As predators, dolphins play an important role in maintaining the complexity of food webs and their stability in the face of climate change, while their sensitivity to prey movements and changes in coastal conditions make them a potentially good indicator of climate-induced change. At the same time dolphin watching eco-tourism may provide supplementary income opportunities for local people, with livelihood diversification being a key element of local climate change adaptation. In vulnerability and capacity assessments in these provinces, local stakeholders also reaffirmed this interest in Irrawaddy dolphins. While relatively more was already known about Irrawaddy dolphins in Trat, with an active local conservation group, and regular surveys conducted by the Department of Marine and Coastal Resources, it was found that there was very little knowledge or understanding of the situation of Irrawaddy dolphins in Koh Kong, and no active involvement in dolphin management of either local communities or local government agencies. In this context, the BCR project decided to support training of local government and local fishermen in survey methods, and to support baseline surveys of Irrawaddy dolphins and other coastal cetaceans in and around the Peam Krasop Wildlife Sanctuary (PKWS) of Koh Kong Province. Cetacean expert Brian Smith (WCS/IUCN Cetacean Specialist Group) led the training, surveys and report writing together with IUCN staff and local counterparts. This report presents the results of that work. Recommendations for dolphin conservation and management will be integrated as priority actions in the PKWS Management Plan, the development of which is also supported by BCR. At the same time, IUCN will make every effort to secure additional funding for dolphin conservation in this area over the longer term, beyond the lifetime of the BCR project. Robert Mather Head, IUCN Southeast Asia Group 3

5 Table of contents Acknowledgements... 2 Foreword... 3 List of figures and tables... 5 Executive summary... 7 I. Introduction Previous research on cetaceans in Cambodia Description and status of the three most common cetaceans in Cambodia Irrawady dolphins and climate adaptation Description of the Peam Krasop Wildlife Sanctuary and adjacent coastal waters...11 II. Methods Training Field survey techniques...12 III. Results Search results and cetacean sightings Environmental conditions Photo-identification Census of fishing gear and sand mining dredges...22 IV. Discussion Dolphin distribution, adundance, group sizes and habitat preference Range declines due to habitat disturbance Photo-identification and evidence for fisheries interactions Fisheries and the potential for fatal entanglement of dolphins and porpoises Implications for climate change adaptation...28 V. Conclusions and recommendations Dolphin management areas Educational outreach Research and monitoring...30 VI. References...31 VII. Appendices Appendix 1: Handbook for a dolphin assessment in the Peam Krasop Wildlife Sanctuary, Cambodia Appendix 2: Survey participants

6 List of figures and tables I. Figures Figure 1: A training course for the survey team was held at the Coastal Resources Centre at Department of Environment in Koh Kong which included both classroom presentations and discussions (left) and well as practical exercises in the use of survey equipment (right)...12 Figure 2: Survey team searching for dolphins and porpoises in the coastal waters offshore the Peam Krasop Wildlife Sanctuary...13 Figure 3: Map of the systematic tracklines and the location of cetacean sightings during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters...14 Figure 4: Map of the opportunistic tracklines and the location of cetacean sightings during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters...15 Figure 5: Map of the systematic tracklines and the location of cetacean sightings during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters...15 Figure 6: Map of the route while searching opportunistically and the location of cetacean sightings during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary...16 Figure 7: Satellite image from Google Earth showing the approximate areas (outlined in red) where figure dolphins were generally found...17 Figure 8: Photo-catalogue of 15 Irrawaddy dolphins identified by distinctive marks on their dorsal fin including specimen number and data identified Figure 9: Photo-catalogue of two humpback dolphins identified by distinctive marks on their dorsal fin including specimen number and data identified...22 Figure 10: Map of the systematic tracklines and the location of fishing gears and vessels during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary...23 Figure 11: Map of the systematic tracklines and the location of sand dredging operations during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary...24 Figure 12: Map of the systematic tracklines and the location of fishing gears and vessels during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary...25 Figure 13: Map of the systematic tracklines and the location of sand dredging operations during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary

7 Figure 14: Large numbers of sand mining dredgers operating in the Trapeang Roung Channel are degrading key fisheries habitat and may have resulted in dolphins abandoning the area as part of their range on the Peam Krasop Wildlife Sanctuary...26 Figure 15: Monofilament gillnet (a) used to catch shrimps are a hazard to cetaceans due to the potential for fatal entanglement (left) and fishing trawlers (b) from Thailand operating illegally in the coastal waters of Cambodia may be causing declines in fisheries and in the availability of cetacean prey (right)...28 II. Tables Table 1: Salinity and depth recorded every 30 minutes while surveying along systematic tracklines and searching opportunistically and at the location of Irrawaddy dolphin sightings during the first survey...18 Table 2: Temperature and turbidity recorded every 30 minutes while surveying along systematic tracklines and searching opportunistically and at the location of Irrawaddy dolphin sightings during the second survey

8 Executive summary The Peam Krasop Wildlife Sanctuary (PKWS) is among the most significant protected areas in Cambodia and most significant mangrove forests in Southeast Asia. Three globally threatened small cetaceans including Irrawaddy dolphins (Orcaella brevirostris), Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) live in the mangrove channels, gulfs and adjacent coastal waters of the sanctuary. An intensive 4-day training course was held for a team of 12 local researchers on dolphin assessment techniques followed by surveys of these waters during 10 days in October and November 2013 and seven days in February During the first survey the team searched along 408 km of systematic trackline and made six sightings of Irrawaddy dolphins for an encounter rate of 1.5 groups/100 km and mean group size of 4.8 individuals, and a single sighting of finless porpoises with a group size of 8-10 individuals. They also searched along 194 km of opportunistically determined trackline and made 13 sightings of Irrawaddy dolphins with an encounter rate of 6.2 groups/100 km and a mean group size of 10.7 individuals. During the second survey they covered 332 km of systematic trackline and made three sightings of Irrawaddy dolphins with an encounter rate of 0.9 groups/100 km and a group size of one, two, and 10 individuals. They also searched along km of opportunistically determined trackline and made six sightings of Irrawaddy dolphins with an encounter rate of 4.3 groups/100 km and a mean group size of 5.5, and a single sighting of seven humpback dolphins. Irrawaddy dolphins were found most frequently just offshore the Prek Bak Khlong, Old Peam Krasop, and Lam Dam channel mouths as well as along the northwest coast of Koh Kong Island in waters affected by freshwater outflow from the Trapeang Roung and Tatai Rivers. Although the overall number of Irrawaddy dolphin sightings was low, group sizes were high ranging up to 19 individuals. Group sizes were almost double and sightings much more frequent while following opportunistic versus systematic transect lines probably because the prior took the survey team through the main channels linking inland waters and open seas which are the preferred habitat of the species. The survey team took about 3,200 photographs of Irrawaddy and humpback dolphins. Fifteen Irrawaddy dolphins were identified from distinctive marks on their dorsal fins. Seven of these individuals were re-identified on one or two occasions. Minimum abundance was estimated from the minimum count (15) plus the estimated number of unmarked individuals calculated according to the proportion of marked versus unmarked photographs for a total of 36 Irrawaddy dolphins with a 95% confidence interval of Only two humpback dolphin individuals were identified from dorsal fin marks during the single sighting of the species made during the second survey. These surveys found that a significant number of Irrawaddy dolphins inhabit open waters just outside the mouths of waterways leading in and out of the mangrove forest indicating the particular suitability of this habitat for the species. Although no empirical information is available on the historical distribution of the Irrawaddy dolphins, anecdotal reports suggest that their range has declined inside the mangrove forest due to intensive sand mining and extensive mussel aquaculture. The density of fishing activity was fairly high and monofilament gillnets are of particular conservation concern due to the strong potential for fatal entanglements. Trawlers in nearshore waters may also be a concern because mortality in trawl nets can threaten local populations. The clumped distribution of the dolphins in the mouths of channels leading in and out of the mangrove forest offers key opportunities for conservation management in terms of taking a zoning approach to fisheries that threaten the dolphins (e.g. gill nets and possibly trawl 7

9 fisheries) due to accidental entanglements and for developing well-managed ecotourism focused on dolphin watching. The same distributional characteristics of the dolphins also present an opportunity to use them as an informative tool for evaluating and adapting to the ecological impacts of climate change. 8

10 I. Introduction 1.1 Previous research on cetaceans in Cambodia A great deal of attention has been paid to investigating the population status and ecology of the Mekong River population of Irrawaddy dolphins (Baird and Mounsouphom 1997; Baird and Beasley 2005; Ryan et al. 2011; Beasley et al. 2012). This small dolphin population resides almost exclusively in Cambodia with a few individuals remaining in an isolated pool just across the border in Laos. The emphasis on this population is not surprising because it is one of only three riverine populations of the species all considered critically endangered by the IUCN (Kreb and Smith 2000, Smith 2004, Smith and Beasley 2004). Meanwhile little attention has been paid to investigating marine populations of Irrawaddy dolphins (Orcaella brevirostris) in Cambodia despite the fact that preliminary surveys indicate the country s coastal waters support regionally significant populations of the species, as well as other small cetaceans at conservation risk. These include finless porpoises (Neophocaena phocaenoides) and Indo-Pacific humpback dolphins (Sousa chinensis) (Beasley and Davidson 2007). The only dedicated investigation on cetaceans in the coastal waters of Cambodia surveyed a little more than 2,000 km. It documented eight small cetacean species including Irrawaddy dolphins, finless porpoises, Indo-Pacific humpback dolphins, false killer whales (Pseudorca crassidens), long-beaked common dolphins (Delphinus capensis, probably the extra-longbeaked tropicalis subspecies), pantropical spotted dolphins (Stenella attenuata), spinner dolphins (S. longirostris, probably the dwarf roseiventris subspecies), and Indo-Pacific bottlenose dolphins (Tursiops aduncus). Irrawaddy dolphins were the most common coastal cetacean sighted during these surveys (Beasley and Davidson 2007). Of the coastal waters surveyed by Beasley and Davidson (2007), Koh Kong Bay and around Koh Kong Island heading north to the Thai border appeared to be particularly important for both Irrawaddy and Indo-Pacific humpback dolphins with eight and four sightings of these species, respectively, made during only five hours of survey effort. The Irrawaddy dolphins documented in this area may be part of a continuous population ranging from southern Vietnam to the upper Gulf of Thailand where relatively large numbers of Irrawaddy dolphins were recorded by Hines et al. (2012). 1.2 Description and status of the three most common coastal cetaceans in Cambodia (a) Irrawaddy dolphins The Irrawaddy dolphin is about 2.0 to 2.5 m long. This dolphin has a rounded head that overhangs the mouth and a crescent-shaped blowhole. It has no visible beak. A neck crease is visible in some individuals. Its dorsal fin is small, triangular, and slightly swept back with a blunt tip. Coloration is all gray but lighter on the belly (Jefferson et al. 2008) Irrawaddy dolphins occur in small groups of generally 1-5 individuals. The species ranges in near- and inshore waters of the western Pacific and eastern Indian Ocean in habitat generally associated with river mouths. They also occur far upstream in three large rivers including the Ayeyarwady in Myanmar, Mekong in Cambodia and Laos, and Mahakam in Indonesia (Smith 2009). Irrawaddy dolphins are considered Vulnerable by the IUCN due to at least a 30 percent reduction in their range-wide population. Five Critically Endangered populations occur in three large rivers and in Chilikha Lagoon, India, and Malampaya Sound, Philippines. Populations generally number in the 10s to low 100s with the single exception of Bangladesh 9

11 which supports approximately 5,800 dolphins. About 400 occur in waterways of the Sundarbans and 5,400 in the coastal waters offshore of the mangrove forest (Reeves et al. 2008a). Irrawaddy dolphins have been documented accidentally caught in fishing nets in almost all areas where they have been studied. Their habitat is particularly affected by increasing salinity due to climate change and increasing freshwater withdrawals. In Bangladesh, Irrawaddy dolphins are thought to be killed accidentally in large numbers by a drifting gill fishery targeting sharks and rays (Reeves et al. 2008a). (b) Indo-Pacific humpback dolphins Indo-Pacific humpback dolphins have a robust body and long beak. They obtain a maximum size of about 2.8 m. Their dorsal fin sits on a hump which varies in size according to region and is located in the middle of the dolphin s back. Their color pattern differs with age and region but adults are generally bluish gray to light cream-colored with a pinkish hue. Humpback dolphins can most easily be confused with bottlenose dolphins (Jefferson et al. 2008). Humpback dolphins are normally found in groups of fewer than 10 individuals although as many as 100 have been occasionally seen together. Indo-Pacific humpback dolphins occur in shallow, coastal waters of the northern Indian and eastern Pacific oceans generally associated with freshwater inputs. The only waters where they range offshore are over broad continental shelves less than 100 m deep (Reeves et al. 2008b). The Indo-Pacific humpback dolphin is considered Near Threatened in the IUCN Red List, but likely Vulnerable if the chinensis type of the species in the central and western Indian Ocean, and the plumbea type of the species in the eastern Indian and western Pacific oceans were evaluated separately. (c) Finless porpoise The finless porpoise is slightly smaller than the Irrawaddy dolphin and has no dorsal fin. Adults reach about 1.9 meter length. Their body is dark gray and torpedo shaped with a rounded head and no beak. Finless porpoises are generally found in groups of 1-2, but occasionally up to 20, individuals. They are difficult to observe at sea due to their inconspicuous surfacing behavior and lack of dorsal fin (Jefferson et al. 2008). Finless porpoises occur in tropical to warm temperate shallow waters of the Indo-Pacific. They are normally found in shallow bays and estuaries although they can also occur far from shore over broad continental shelves. In Bangladesh finless porpoises generally prefer deeper and more saline waters compared to Irrawaddy dolphins. Similar to the Irrawaddy dolphin, the finless porpoise is considered Vulnerable by the IUCN due to at least a 30 percent reduction in their range-wide population. Finless porpoises are extremely vulnerable to entanglement in gillnets (Wang and Reeves 2012). 1.3 Irrawaddy dolphins and climate adaptation Climate change will dramatically affect the ecology of estuarine waters. Major changes are expected to salinity and turbidity regimes which are linked to the timing and availability of freshwater flows as well as to sea-level rise. Changes in sedimentation patterns will also have corresponding impacts on bathymetry. The general lack of knowledge on the ecological implications of climate change in the PKWS and adjacent coastal waters inhibits the development of science-based management approaches required for biodiversity conservation and human adaptation. Biological shortcuts are needed to make inferences about potential climate change impacts and appropriate management options. An indicator 10

12 value for Irrawaddy dolphins has been proposed to inform ecosystem management and climate adaptation. As large, mobile predators the manner by which these dolphins satisfy their life history needs including their movement patterns, habitat use, and foraging behavior may give them particular value for identifying ecologically significant attributes such as local aggregations of biological productivity for site-based protection and monitoring (Smith and Reeves 2012). 1.4 Description of the Peam Krasop Wildlife Sanctuary and adjacent coastal waters The Peam Krasop Wildlife Sanctuary (PKWS) is among the most significant protected areas in Cambodia. It is relatively large (~26,000 hectares) and it connects a biologically intact mangrove forest in the west with evergreen forest in the east. Estuarine waters in the PKWS are strongly influenced by seasonally fluctuating fresh water inputs and diurnal tides. These conditions provide ideal environmental conditions for productive fisheries that benefit the 13 local communities found within its boundaries (Dara et al. 2009). However these same conditions also mean that waterways in the PKWS and adjacent estuarine sea are extremely vulnerable to climate change because both environments are trapped between altered freshwater regimes in the upstream watershed and rising sea-levels which will cause increase salinity incursion and increases in sedimentation. Since the collapse of the Khmer Rouge regime there has been a major increase in the migration of people to the Koh Kong area with a 16% estimated average annual growth rate (Riza and Singer 2011). This rapid increase in human population and the consequent increase in demands it has placed on natural resources in the PKWS threatens biodiversity as well as the sustainability of local fisheries in waterways of the mangrove forest and adjacent coastal waters. These fisheries provide much needed protein, income and employment for local communities that include both long-term residents and recent migrants. II. Methods 2.1 Training Between 23 and 26 October 2013 a training course was conducted on cetacean survey techniques for 12 local researchers (Figure 1). Prior the training course a comprehensive handbook was prepared (Appendix 1). Topics addressed during presentations and field exercises included (1) sighting and identifying cetaceans, (2) general procedures for surveys of cetaceans, (3) double counts from independent teams and distance-dive time models, (4) line-transect surveys in coastal waters, (5) photo-identification, (6) using a global positioning system, (7) investigating environmental parameters, (8) investigating the abundance and distribution of fishing gears, and (9) dolphin carcass examination and sampling protocol. On the last day of the training all participants participated in a practice survey (Appendix 2). 11

13 Figure 1. A training course for the survey team was held at the Coastal Resources Centre at Department of Environment in Koh Kong which included both classroom presentations and discussions (left) and well as practical exercises in the use of survey equipment (right). 2.2 Field survey techniques Surveys were conducted from a 14.7 meter long wooden vessel with a 22 horsepower longtail motor (Figure 2). Two observers stood watch at all times searching with 7X50 binoculars from beam to beam. A third observer, who also served as the data recorder, searched by naked eye. Every 30 minutes and at the location of cetacean sightings, a geographic position was recorded with a Global Positioning System (GPS) together with information on sighting conditions, water surface temperature, depth, salinity, turbidity, and the distance covered along the transect line. A careful record was kept on sighting conditions to assess their effects on detection rates. Wind, glare, or rain/fog conditions were given codes of 0, 1, or 2, corresponding to good (no effect on sighting conditions), fair (small effect on sighting conditions), and poor (large effect on sighting conditions), respectively. More specifically, for wind, code 0 meant was used when the water surface was glassy or had only small ripples; code 1 was used when there were small waves but no white caps; code 2 was used for larger waves with whitecaps. For glare, code 0 was used for no glare, code 1 when there was severe glare (view completely obscured) covering less than 10% of the field of view or slight glare (view only partially obscured) covering less than 50% of the field of view, and code 2 when there was severe glare covering more than 10% of the field of view or slight glare covering more than 50% of the field of view. For rain/fog, code 0 was used when the was no fog or rain, code 1 when fog or rain obscured no more than 10% of the field of view or partially obscuring no more than 50% of the field of view, and code 2 when fog or rain obscured more than 10% of the field of view or partially obscured more than 50% of the field of view. When a cetacean groups was sighted a geographic position was immediately recorded on a GPS, along with (1) the time from the GPS; (2) the observer who first detected the dolphin group; (3) the estimated radial distance and angle to the animals; (4) best, high, and low estimates of group sizes; and (5) temperature, depth, salinity, and turbidity. The survey team also took photographs of the dorsal fins of the observed dolphins. The boat operator approached dolphin groups slowly, and efforts were made to navigate the boat parallel to the group s direction of travel. Every attempt was made to obtain high quality photographs taken at a perpendicular angle to the body of the dolphins present in a group. 12

14 Figure 2. Survey team searching for dolphins and porpoises in the coastal waters offshore the Peam Krasop Wildlife Sanctuary. While searching for dolphins, a separate observer also maintained watch and recorded data on active fishing vessels (i.e., those with their gear deployed, and not just underway or drifting) and fixed gears, as well as sanding mining operations. Data were recorded on the geographic position, number of gears, and fishing gear type. III. Results 3.1 Search effort and cetacean sightings During the first survey, over a period of 10 days from 27 October - 7 November 2013, the survey team covered km during 59.6 hours of searching effort. Of the total search effort, km were covered during 39.4 hours (mean vessel speed = 10.4 km/hr) while following systematic tracklines (Figure 3). While following these tracklines sightings conditions were considered as good, fair, and poor during 78.2%, 17.4%, and 4.4% of the total distance covered, respectively. The remaining search effort, consisting of km during 20.1 hours (mean vessel speed = 9.7 km/hr), was conducted opportunistically while traveling to and from the day s starting and end points (Figure 4). Sighting conditions during opportunistic search effort were good and fair during 99.0% and 1.0% of the total distance covered. While searching along systematic tracklines during the first survey the team made six sightings of Irrawaddy dolphins for an encounter rate of 1.5 groups/100 km and mean group size of 4.8 individuals (median=5.0, SD=2.1, range=2-8), one sighting of finless porpoises with a group size of 8-10 individuals, and one sighting of a single unidentified small cetacean. All sightings were made during good survey conditions (Figure 3). Environmental conditions documented for Irrawaddy dolphin sightings along the trackline were a mean salinity of 26.5 ppt (median=30.0, SD=7.6, range= ), mean depth of 11.4 m (median=9.3, SD=8.3, range= ), mean temperature of 30.6 C (median 30.1, SD=1.3, range= ) and mean turbidity of 1.4 NTUs (median=1.4, SD=0.4, range= ). Environmental conditions for the single sighting of finless porpoise were 25 ppt for salinity, 8.5 m for depth, 29.8 C for temperature, and 1.2 NTUs for turbidity. 13

15 Figure 3. Map of the systematic tracklines and the location of cetacean sightings during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters. While searching opportunistically during the first survey the team made 13 sightings of Irrawaddy dolphins with an encounter rate of 6.2 groups/100 km and a mean groups size of 10.7 individuals (median=8, SD=5.9, range=3-19) and no sightings of other species (Figure 4). All sightings were made during good survey conditions. Environmental conditions documented for Irrawaddy dolphin sightings along opportunistic tracklines were a mean salinity of 27.6 ppt (median=28.0, SD=2.2, range=24-31), mean depth of 5.9 m (median 4.7, SD=3.6, range= ), mean temperature of 30.0 C (median=30.0, SD=0.5, range= ), and mean turbidity of 1.5 NTUs (median=1.5, SD=0.8, range= ). Figure 4. Map of the opportunistic tracklines and the location of cetacean sightings during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters. 14

16 During the second survey from February 2014, the survey team covered km during 49.4 hours of searching effort (Figure 5). Of the total search effort, km were covered during 33.9 hours (mean vessel speed = 9.8 km/hr) searching along systematic tracklines. While following these tracklines sightings conditions were good, fair, and poor during 71.8%, 20.1%, and 8.1% of the total distance covered, respectively. The remaining search effort, conducted opportunistically while traveling to and from the day s starting and end points, was comprised of km during 15.4 hours (mean vessel speed = 9.7 km/hr) (Figure 6). Sighting conditions during opportunistic search effort were good, fair, and poor during 66.6%, 30.7%, and 2.7% of the total distance covered. While searching along systematic tracklines the survey team made three sightings of Irrawaddy dolphins with an encounter rate of 0.9 groups/100 km and a group size of one, two, and 10 individuals, and one sighting of three unidentified small cetaceans (Figure 5). All sightings were made during good survey conditions with the exception of a single sighting of Irrawaddy dolphins made during fair conditions. Environmental conditions documented for the three Irrawaddy dolphin sightings made along the trackline ranged between ppt for salinity, m for depth, C for temperature, and NTUs for turbidity. Figure 5. Map of the systematic tracklines and the location of cetacean sightings during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary and adjacent coastal waters. While searching opportunistically during the second survey, the team made six sightings of Irrawaddy dolphins with an encounter rate of 4.3 groups/100 km and a mean groups size of 5.5 individuals (median=2.5, SD=6.2, range=1-17) and a single sighting of seven humpback dolphins (Figure 6). All sightings were made during good survey conditions. Environmental conditions documented for Irrawaddy dolphin sightings made while searching opportunistically were a mean salinity of 31.0 ppt (median=31.0, SD=0.6, range= ), mean depth of 6.8 m (median 6.5, SD=4.3, range= ), mean temperature of 27.7 C (median=27.7, SD=0.2, range= ), and mean turbidity of 3.3 NTUs (median=2.8, SD=1.9, range= ). Environmental conditions for the single sighting of humpback dolphins were 32 ppt for salinity, 5.1 m for depth, 27.5 C for temperature, and 6.0 NTUs for turbidity. 15

17 Figure 6. Map of the route while searching opportunistically and the location of cetacean sightings during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary. Irrawaddy dolphins were found most frequently just offshore the Prek Bak Khlong, Old Peam Krasop, and Lam Dam channel mouths as well are along the northwest coast of Koh Kong Island in nearshore waters affected by freshwater outflow from the Trapeang Roung and Tatai Rivers (Figure 7). Although the overall number of Irrawaddy dolphin sightings was fairly low, group sizes were relatively high ranging up to a best estimate of 19 individuals. These are the largest group sizes for Irrawaddy dolphins reported in the literature which are generally reported to be between two and six individuals with up to 15 when two or more groups come together (Smith 2009). Group sizes were almost double (T-test = , P<0.05, df=24) for sightings made off the systematic tracklines (mean=9.6) versus on the trackline (mean=4.7) probably because the routes travelled while searching opportunistically generally took the survey team through the main channels linking inland waters and open seas (particularly the Old Peam Krasop channel mouth which was close to where we started and ended the survey each day) and south of the Lam Dam channel in estuarine waters known from other studies to be the preferred habitat of the Irrawaddy dolphins (e.g. see Smith et al. 2004, 2008). 16

18 Figure 7. Satellite image from Google Earth showing the approximate areas (outlined in red) where Irrawaddy dolphins were generally found. 3.2 Environmental conditions Due to technical difficulties with environmental sampling equipment during the first survey and engine problems that resulted in incomplete survey coverage during the second survey, a valid comparison cannot be made between temperature, salinity and turbidity measurements recorded during the two surveys, nor can a quantitative analysis be conducted of habitat preferences. However, the results of environmental sampling were roughly consistent with the known habitat preferences of Irrawaddy dolphins in shallow waters characterized by relatively low salinity and moderate turbidity (Table 1 and 2). 17

19 Table 1. Salinity and depth recorded every 30 minutes while surveying along systematic tracklines and searching opportunistically and at the location of Irrawaddy dolphin sightings during the first survey. Salinity Depth First Survey Count Mean Median SD Range Count Mean Median SD Range On track effort Off track effort On track sightings Off track sightings Second Survey On track effort Off track effort On track sightings* Off track sightings N/A N/A N/A N/A N/A N/A *Only the range given due to low number of sightings. 18

20 Table 2. Temperature and turbidity recorded every 30 minutes while surveying along systematic tracklines and searching opportunistically and at the location of Irrawaddy dolphin sightings during the second survey. Temperature Turbidity First Survey Count Mean Median SD Range Count Mean Median SD Range On track effort Off track effort On track sightings Off track sightings Second Survey On track effort Off track effort On track sightings* Off track sightings N/A N/A N/A N/A N/A N/A

21 3.3 Photo-identification The survey team took about 2,100 photographs during nine days of the first survey and about 1,100 photographs during seven days of the second survey. Of the total photographs, only 248 or 7.8% included one or more dorsal fin images that were good enough quality to be used for photo-identification purposes. This meant that diagnostic feature such as nicks, scars and mutilations on the dorsal fin would be visible if present. Of the good quality photographs only 104 or 41.9% included marks that would allow for the identification of individuals while 144 or 58.1% had no marks that would allow for the identification of individuals. From a preliminary analysis of the photographs 15 Irrawaddy dolphin individuals were identified (Figure 8). Five of these individuals were re-identified on one or two occasions during first survey. No new identifications were made during the second survey but two individuals were re-identified from the first survey (Figure 8). Only two humpback dolphin individuals were identified during a single sighting made during the second survey (Figure 9). The lack of new identifications during the second survey could be interpreted as evidence that we identified most or all of marked individuals in the population. However it may also be explained by changes in equipment and photographers between the first and second survey. Sample sizes were too small for estimating population parameters such as abundance, survival and movements. However, according to the photo-identification catalog there are at least 15 individuals. A minimum estimate of population size corrected for the number of unmarked individuals was modeled according to the minimum count (15) divided by the estimated proportion of marked versus total individuals (0.42), calculated according to the number of marked good quality dorsal fin images (104) divided by the total number of good quality dorsal fin images (248). This equals 36 with a 95% confidence interval (CI) of The 95% CI was calculated according to the standard error of a linear regression of unmarked good quality images of dorsal fins versus the total number of dorsal fin images recorded during each survey day (R=0.991, P<0.001) which equals

22 OB 1 (03 Nov 2013) OB OB 5 (01 5 (1 Nov 2013) OB 8 (03 Nov 13) OB 2 (01 Nov 2013) OB OB 55 (03 (3 Nov 2013) OB 9 (31 Oct 2013) OB 3 (03 Nov 2013) OB 6 (01 Nov 2013) OB 9 (03 Nov 2013) OB 4 (28 Oct 2013) OB 6 (16 Feb Feb 2014) OB 10 (27 Oct 2013) OB 4 (16 Feb 2014) OB 7 (01 Nov 2013) OB 11 (27 Oct 2013) OB 5 (30 Oct 2013) OB 7 OB (037 Nov (03 Nov 2013) 2013) OB 12 (27 Oct 2013) Figure 8. Photo-catalog of 15 Irrawaddy dolphins identified by distinctive marks on their dorsal fin including specimen number and data identified. Boxed text indicates re-identification. Note that some marks used for identification purposes are not visible in these low-resolution photographs. 21

23 OB 12 (31 Oct 2013) OB 13 (31 Oct 2013) OB 12 (31 Oct 2013) OB 14 (03 Nov 2013) OB 12 (03 Nov 2013) OB 13 (03 Nov 2013) OB 12 (03 Nov 2013) OB 13 (03 Nov 2013) OB 15 (03 Nov 2013) Figure 8 (continued). Photo-catalog of 15 Irrawaddy dolphins identified by distinctive marks on their dorsal fin including specimen number and data identified. Boxed text indicates re-identification. SC 1 (12 Feb 2014) SC 2 (12 Feb 2014) Figure 9. Photo-catalog of two humpback dolphins identified by distinctive marks on their dorsal fin including specimen number and data identified. 3.4 Census of fishing gear and sand mining dredges During the first survey fishing gears recorded while following systematic transect lines (Figure 10) included: (a) 57 squid trap boats with a mean of 98.8 traps/boat (median=100, SD=5.4, range=70-100); (b) 40 set bag net clusters with a mean of 7.2 nets per cluster (median=6.0, SD=3.9, range=2-24), estimated length of 40m per net and a mouth width of 10-13m, and no attending boats; (c) (24 fishing trawler clusters with a mean of 3.5 vessels/cluster (median=2, SD=3.2, range=1-13) with an estimated net length of 30m; (d) 15 scoop net light boats (note that these vessels are from Thailand apparently fishing illegally in Cambodian waters); 22

24 (e) 12 gill net clusters with an mean of 1.5 nets and boats/cluster (median=1, SD=1.1, range=1-4) and mean net length of 462.9m (median=400, SD=351.6, range=40-1,000); (f) 11 blue swimming crab (Portunus pelagicus) trap vessels with a mean of 1,450 traps/vessel (median=300, SD=1,486, range=300-3,000); (g) 10 squid shell trap boats with a mean of 6,500 traps/vessel (median=5,500, SD=3,507, range=5,500-12,000); (h) six trolling hook and line boat clusters with a mean of 2.7 boats/cluster (median 2.0, SD=2.2, range=2-7); (i) 6 shrimp gill-net clusters with a mean of 1.7 gill nets/cluster (median=1.5, SD=0.8, range=1-3) and mean length of 366.7m (median=400, SD=150.6, range= ); (j) three fish trap clusters with a mean of 43.3 traps/cluster (SD=11.5, range=30-50); and (k) three hook and line vessels with 2-6 hook and lines per vessel. Figure 10. Map of the systematic tracklines and the location of fishing gears and vessels during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary. In addition to the fishing gears documented above, during the first survey the team also recorded 106 sand mining dredges and sand barges in 16 clusters concentrated in along the Trapeang Roung River near Koh Smarch Point to Koh Sraloa through to the Lam Dam Channel (Figure 11). 23

25 Figure 11. Map of the systematic tracklines and the location of sand dredging operations during the first survey for cetaceans in the Peam Krasop Wildlife Sanctuary. During the second survey fishing gears recorded while following systematic transect lines (Figure 12) included: (a) 25 set bag net clusters with a mean of 7.7 nets per cluster (median=6.0, SD=3.5, range=6-15), estimated length of 40m per net and a mouth width of 8.0m, and no attending boats; (b) 20 blue swimming crab trap vessels with a mean of 858 traps/vessel (median=400, SD=1,134, range=400-4,000); (c) 15 trawler clusters with a mean of 3.5 boats/cluster (median=2.0, SD=5.1, range=1-20) and estimated net length of 30m for all trawlers; (d) nine squid trap boats with a mean of traps/boat (median=100.0, SD=34.8, range= ); (e) six gill net clusters with an mean of 1.2 nets and boats/cluster (median=1, SD=0.4, range=1-2) and mean net length of 833.3m (median=450, SD=1,074.6, range=200-3,000); (f) five squid shell trap boats with a mean of 3,063 traps/vessel (median=3,500, SD=2,045, range=250-5,000); (g) two scoop-net light boat clusters of one and three boats (note that these vessels are from Thailand apparently fishing illegally in Cambodian waters); (h) two shrimp gill net vessels with a net length of about 400m; (i) two fish trap clusters with 50 and 70 traps per cluster; (j) two shrimp scoop-net clusters of 2 and 3 boats; (k) one blue swimming crab gillnet with an estimated net length of 1000m; 24

26 (l) one trolling hook and line boat with two lines and hooks; and (m) one long line vessel with about 2,000 hooks. Figure 12. Map of the systematic tracklines and the location of fishing gears and vessels during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary. In addition to the fishing gears documented above, during the second survey the team also recorded 37 sand mining dredges and sand barges in five clusters located similar to the first survey along the Trapeang Roung River near Koh Smarch Point to Koh Sraloa through to the Lam Dam Channel (Figure 13). Figure 13. Map of the systematic tracklines and the location of sand dredging operations during the second survey for cetaceans in the Peam Krasop Wildlife Sanctuary. 25

27 IV. Discussion 4.1 Dolphin distribution, abundance, group sizes, and habitat preferences The results of the two sighting surveys are insufficient to estimate the abundance of Irrawaddy dolphins in the PKWS and adjacent coastal waters. However, the surveys do indicate that a significant number of dolphins inhabit the area especially in open waters just outside the mouths of waterways leading in and out of the mangrove forest. The single sighting of a group of finless porpoise in open waters and humpback dolphins inside the mangrove forest provide further evidence of the biological productivity of these waters and their capacity to support coastal cetaceans. However, the relatively low number of sightings of humpback dolphins and finless porpoises compared to Irrawaddy dolphins also lends additional support to a study in Bangladesh which indicated that all three species partition themselves according to habitat with Irrawaddy dolphins generally preferring less saline and more nearshore/inshore waters compared to the other two species (Smith et al. 2008). The relatively frequent occurrence of Irrawaddy dolphins in open waters just offshore the channel mouths of the PKWS, as well as the larger sizes of groups found in these waters, indicate that this habitat is particularly suitable for the species. Indeed the largest best group size estimate made during the surveys of 19 individuals is the largest ever recorded for the species. These results also imply that efforts to protect Irrawaddy dolphins, particularly from entanglement in fishing gears, should focus on these areas. 4.2 Range declines due to habitat disturbance Although no empirical information is available on the historical distribution and abundance of Irrawaddy dolphins in the PKWS, anecdotal reports from local community members indicate that their range has declined inside the mangrove forest. According to these reports, the dolphins have disappeared from the Trapeang Roung Channel to Koh Sraloa, due to habitat degradation caused by intensive sand mining (Figure 14). Similar reports also indicate that dolphins may have disappeared from the area around Koh Kang and Chroy Bros Gulf due to extensive mussel aquaculture which uses thousands of poles as substrate for mollusks. Due to the high density of these poles just below the water surface during high tide, they create a physical barrier to dolphin movements. Consistent reports from local people, no dolphin sightings were made in these waters. However, our survey coverage was compromised by the navigational hazard created by the submerged poles. Figure 14. Large numbers of sand mining dredgers operating in the Trapeang Roung Channel are degrading key fisheries habitat and may have resulted in dolphins abandoning the area as part of their range on the Peam Krasop Wildlife Sanctuary. 26

28 4.3 Photoidentification and evidence for fisheries interactions Preliminary results of photoidentification efforts are encouraging in terms of the availability of sufficient marks on the dorsal fin, including nicks, notches, scars and mutilations, which can be used to identify individual dolphins. However, the prevalence of these types of marks may also indicate a serious threat from entanglement in fishing gears especially gillnets. Entanglement in gillnets is the most serious threat facing small cetaceans worldwide and it can be assumed that there will be fatal interactions anywhere these nets are deployed in dolphin and porpoise habitat (Perrin et al. 1994). Photographs of dorsal fins indicate that a significant portion have suitable marks to allow for the identification of individuals. However, a large portion of photographs were unmarked. This means that mark-resight methods would result in a more precise and less biased abundance estimate compared to traditional mark recapture models. Mark-resight methods are a variation on the mark-recapture theme in that they account for imperfect detection during the estimation process by utilizing information on sightings of unmarked individuals (Mansur et al 2012). In addition, if a longer time series of photo-identification data becomes available, recent developments in mark-resight models permit the use of the robust design that also estimates survival and temporary immigration and emigration (McClintock et al. 2006, McClintock and White 2009). This information is particularly important for understanding whether or not Irrawaddy dolphins in the PKWS and adjacent coastal waters are resident to the area or part of a larger metapopulation extending north across the border with Thailand, and south and then east along the coast of Cambodia and possible into Vietnam. Scars and mutilations connected with fishing gear entanglements can be documented from identified individuals (Mansur et al. 2012). Complete or partial disfigurements, deep notches or gouges on the leading or trailing edge of the dorsal fin, or deep furrows anterior or posterior to the dorsal fin can considered as almost certainly related to fisheries interactions. The accumulation of these marks over time may be used to calculate the probability of injurious interactions with fisheries. 4.4 Fisheries and the potential for fatal entanglement of dolphins and porpoises The density of fishing activity is fairly high in PKWS and adjacent coastal waters. Monofilament gillnets are of particular conservation concern due to the strong potential for fatal entanglements (Figure 15a). These types of nets result in high rates of mortality that can cause the extirpation of even relatively large populations. Almost all of the gill net clusters recorded during both surveys were found in the Old Peam Krasop and Lam Dam channels, which were also the locations where the largest concentration of Irrawaddy dolphin sightings occurred thus indicating a strong potential fatal entanglements. The large number of trawlers being used in nearshore waters (Figure 15b) may also be a reason for concern because mortality in trawl nets can threaten local cetacean populations (Crespo et al. 2000; Tregenza and Collet 1998). However, there does appear to be differences in bycatch levels among different fisheries. Some are quite high (e.g. in a now closed pair-trawl fishery in the USA bycatch averaged about one dolphin for every five net tows; Fertl and Leatherwood, 1997) and others fairly low with reasons having to do with net dimensions, towing speed, duration, locations where the vessels operate and whether or not the dolphins depredate the fish catch (Northridge, 2002). 27

29 Figure 15. Monofilament gillnet (a) used to catch shrimps are a hazard to cetaceans due to the potential for fatal entanglement (left) and fishing trawlers (b) from Thailand operating illegally in the coastal waters of Cambodia may be causing declines in fisheries and in the availability of cetacean prey (right). Finally the density of set bag nets in the PKWS could be causing fishery declines due to the non-selectivity of the catch. Significant fishery declines have been noted in the PKWS since the 1990s although the causes were mainly attributed to illegal mangrove cutting mainly for charcoal production and illegal dynamite and cyanide fishing, although push netting and trawling was also mentioned (Participatory Management of Mangrove Resources Team 2000). 4.5 Implications for climate change adaptation Investigating seasonal differences in temperature, salinity, and turbidity and the distributional responses of Irrawaddy dolphins can give essential insights into the potential ecological impacts of altered freshwater flow regimes and sea-level rise due to climate change. Due to technical difficulties and incomplete survey coverage we are unable to make any rigorous inferences on climate change impacts. However, the distribution of Irrawaddy dolphins in relatively low salinity waters and in channel mouths leading in and out of the mangrove forest is consistent with their potential role as indicators of priority sites of biological productivity and for monitoring ecological changes at these sites in response to climate change impacts (see Smith and Mansur 2012). V. Conclusion and recommendations Although we were unable to generate an absolute abundance estimate for Irrawaddy dolphins, these surveys confirmed that the PKWS and adjacent coastal waters provide important habitat for this globally threaten species. The clumped distribution of the dolphins in the mouths of channels leading in and out of the mangrove forest offers key opportunities for conservation management in terms of taking a zoning approach to fisheries such gill nets and trawl fisheries that threaten the dolphins due to the potential for accidental entanglements. The same distributional characteristics of the dolphins also present an opportunity for developing well-managed ecotourism focused on dolphin watching, long-term monitoring of the population using tourism vessels as a platform of opportunity, and their use as an informative tool for evaluating and adapting to the ecological impacts of climate change. 28

30 The following recommendations for establishing Dolphin Management Areas and conducting education outreach, research and monitoring aim to protect Irrawaddy dolphins and other small cetaceans and promote their use as a flagship and informative species for climate adaptation in the PKWS and adjacent coastal waters. 5.1 Dolphin Management Areas (a) Dolphin Management Areas should be established in priority habitat for Irrawaddy dolphins in the (1) Prek Bak Khlong channel mouth, (2) Old Peam Krasop channel mouth, (3) Lam Dam channel mouth to the entrance opposite of Chroy Bros Gulf, and (4) nearshore waters directly offshore the first and second coconut farms (Chamkar Doung 1 and 2) on the northwest side on Koh Kong Island (Figure 11). Fishing gears known to cause fatal entanglements of small cetacean, especially gill nets, should be prohibited in these areas. This can be expected to reduce the potential for dolphin entanglements as well as improve fisheries in adjacent waters. A major challenge will be to ensure compliance with newly established regulations in the Dolphin Management Areas. This will require close cooperation with local authorities, community co-management committees, and tourism operators. It will also require close cooperation between the Cambodian Ministry of Environment and the Fisheries Administration since the PKWS is administered by the prior whereas coastal waters are under the jurisdiction of latter. (b) The Dolphin Management Areas described above should be promoted for ecotourism development that aims to benefit local communities and build constituencies for dolphin conservation. A small fee could be charged to dolphin-watching tourists visiting these areas and used for support community development especially benefiting fishermen whose activities will be affected by restrictions on their fishing activities. Dolphin watching guidelines should be developed and followed by tour boat operators to ensure that dolphin-watching activities do not threaten the animals. (c) Enforcement is needed to ensure compliance with the prohibition on trawlers and green mussel aquaculture in the sea grass beds in the Chroy Bros Gulf and Koh Sraloa as well as in the Peam Krasop community protected areas. Alternate sites should be identified in consultation with local communities for culturing the green mussels in locations away from dolphin habitat and their movement corridors. (d) Sand mining in Trapeang Roung River should be eliminated or reduced to protect the rich fish and crustacean nursery habitat provided by sea grass beds in the Koh Sraloa Community Protected Area and the Chroy Bros Community Fishery. 5.2 Educational Outreach (a) An educational outreach program should be employed to raise awareness about the importance of protecting threatened dolphins and porpoises, and to promote their use as flagship species for achieving broader goals related to biodiversity conservation, sustainable fisheries and climate adaptation. One approach that has been shown to be effective in using cetaceans to change the knowledge, attitudes and practices of local communities about sustainable fisheries and climate adaptation in a similar mangrove forest environment in Bangladesh is a yearly interactive, vessel-based exhibition (WCS/BCDP 2014). A similar approach could be taken with Irrawaddy dolphins in the PKWS. Standardized interviews should be conducted before and after educational outreach activities to evaluate their effectiveness and to adapt future educational efforts according to feedback from local communities. 29

31 5.3 Research and Monitoring (a) Photo-identification is a powerful research technique for understanding vital information needed for conservation management including population demography, movements, and the accumulation of marks and wounds associated with fisheries interactions. The value of a photo-identification catalog for conservation management becomes much greater if a sustained effort is made to obtain high quality images of dorsal fins and maintain it over time. A long-term program should be initiated to conduct additional photo-identification effort and to analyze the data. One option to avoid the high costs of conducting dedicated surveys is to piggy back photoidentification efforts onto the dolphin-watching activities mentioned above. This effort will help the tour operators because the photographer can provide information on dolphin ecology and conservation for their clients thus enriching the value of the tour. Individuals identified by distinctive marks on their dorsal fin should be compared with catalogs compiled by researchers in Thailand from just across the Cambodian border in Trat Bay (Junchompoo 2014) and farther east in the Bang Pakong Estuary (Tongnunui 2011) to assess long range movements. (b) As described above, due to their sensitivity to salinity and turbidity which is in turn affected by both freshwater inputs and sea-level rise, information on the fine-scale distribution, habitat use and foraging behavior of Irrawaddy dolphins can be used to evaluate and monitor the ecological impacts of climate change and measures taken for human adaptation. Systematic sampling (i.e., at the same locations and at monthly or bi-monthly intervals) should be made of salinity and turbidity both inside the PKWS and in adjacent coastal waters and at the locations of dolphins sightings. This will allow for long-terms trends to be detected. It will also allow for patterns of dolphin habitat use to be assessed in relation to potential shifts in biological productivity and to guide appropriates management responses. 30

32 VI. References Baird, I. and Beasley, I Irrawaddy dolphin Orcaella brevirostris in the Cambodian Mekong River: an initial survey. Oryx 39(3): Baird, I.G. and Mounsouphom, B Distribution, mortality, diet and conservation of Irrawaddy dolphins (Orcaella brevirostris Gray) in Lao PDR. Asian Marine Biology 14: Beasley, I., and Davidson, P Conservation status of marine Mammals in Cambodian Waters, Including Seven New Cetacean Records of Occurrence. Aquatic Mammals 33(3): Beasley, I., Pollock, K., Jefferson, T. A., Arnold, P., Morse, L., Yim, S., Lor Kim, S. & Marsh, H. (2012) Likely future extirpation of another Asian river dolphin: The critically endangered population of the Irrawaddy dolphin in the Mekong River is small and declining. Marine Mammal Science doi: /j x Crespo, E.A., Alonso, M.K., Dans, S.L., Garcia, N.A., Pedraza, S.N., Coscarella, M. and González, R Incidental catches of dolphins in mid-water trawls for Argentine anchovy (Engraulis anchoita) off the Argentine shelf. J. Cetacean Res. Manage. 2(1): Dara, A. Kimsreng, K., Piseth, H. and Mather, R.J. 2009) An Integrated Assessment for Preliminary Zoning of Peam Krasop Wildlife Sanctuary, Southwestern Cambodia. Gland, Switzerland: IUCN 52p. Fertl, D. and Leatherwood, S Cetacean interactions with trawls: a preliminary review. J. Northwest Atl. Fish. Sci. 22: Northridge, S Fishing industry, effects of. pp In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (eds). Encyclopedia of Marine Mammals. Academic Press, San Diego, CA. 1,414pp. Geyer W.R., Morris, J.T., Prahl, F.G., Jay, D.A Interaction between physical processes and ecosystem structure. In Estuarine Science: A Synthetic Approach to Research and Practice, Hobbie JE (ed.). Island Press: Washington, DC; Hines, E., Chalatip, J., et al. (2012) Coastal marine mammals along the Eastern Gulf of Thailand. Final research report for Ocean Park Conservation Foundation. Unpublished. Jefferson, T.A., Webber, M.A. and Pitman, R.L Marine Mammals of the World. A Comprehensive Guide to their Identification. Elsevier, Amsterdam. Junchompoo, C., Monanunsap, S., Penpein, C Population and Conservation Status of Iirawaddy [sic.] Dolphins (Orcaella brevirostris) in Trat Bay, Trat Province, Thailand. Pages in Proceedings of the Design Symposium on Conservation of Ecosystem (The 13th SEASTAR2000 workshop), Kyoto University Design School. Kreb, D. and Smith, B.D Orcaella brevirostris (Mahakam subpopulation). In: IUCN IUCN Red List of Threatened Species Mansur, R.M., Strindberg, S., Smith, B Mark-resight abundance and survival estimation of Indo-Pacific bottlenose dolphins, Tursiops aduncus, in the Swatch-of-No- Ground, Bangladesh. Marine Mammal Science. McClintock, B. T., and G. C.White A less field-intensive robust design for estimating demographic parameters with mark-resight data. Ecology 90:

33 McClintock, B. T., G. C. White and K. P. Burnham A robust design mark-resight abundance estimator allowing heterogeneity in resighting probabilities. Journal of Agricultural, Biological, and Environmental Statistics 11: Perrin, W.F., Donovan, G.P., Barlow, J. (Eds.), Report of the International Whaling Commission (Special issue 15). Gillnets and Cetaceans. International Whaling Commission, Cambridge, UK. 629pp Participatory Management of Mangrove Resources Team Mangroves Meanderings: Learning About Life in Peam Krasop Wildlife Sanctuary. Unpublished report from IDRC Canada and Ministry of Environment, Cambodia ( Reeves, R.R., Jefferson, T.A., Karczmarski, L., Laidre, K., O Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2008a. Orcaella brevirostris. In: IUCN IUCN Red List of Threatened Species. Version < Reeves, R.R., Dalebout, M.L., Jefferson, T.A., Karczmarski, L., Laidre, K., O Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2008b. Sousa chinensis. In: IUCN IUCN Red List of Threatened Species. Version < Rizvi, A.R. and Singer, U Cambodia Coastal Situation Analysis, Gland, Switzerland: IUCN. 58 pp. Ryan, Gerard Edward, Verné Dove, Fernando Trujillo, and Paul F. Doherty (2011) Irrawaddy dolphin demography in the Mekong River: an application of mark resight models. Ecosphere 2(5): art58. Smith, B.D Irrawaddy Dolphin (Orcaella brevirostris): Ayeyarwady River (Myanmar) subpopulation, Critically Endangered, D, C2a(i, ii) IUCN Red List of Threatened Species. Smith, B.D Irrawaddy dolphin (Orcaella brevirostris). Pages In W.F. Perrin, B. Würsig, and J.G.M. Thewissen (eds.) Encyclopedia of Marine Mammals (2nd edition), Academic Press, Burlington, MA. Smith, B.D. and Beasley, I Irrawaddy Dolphin (Orcaella brevirostris): Mekong River (Laos, Cambodia and Vietnam) subpopulation, Critically Endangered, D, C2a(i, ii) IUCN Red List of Threatened Species. Smith, B.D., and Mansur, E.F Sundarbans. Pages in Hilty, J.A., Chester, C. C., and Cross, M. (eds) Climate and Conservation: Landscape and Seascape Science, Planning and Action. Island Press. Smith, B.D. and R. R. Reeves River cetaceans and habitat change: generalist resilience or specialist vulnerability? Journal of Marine Biology 2012:1-11. Smith, B. D.; Ahmed, B. and Mansur, R Species occurrence and distributional ecology of nearshore cetaceans in the Bay of Bengal, Bangladesh, with abundance estimates for Irrawaddy dolphins Orcaella brevirostris and finless porpoises Neophocaena phocaenoides. Journal of Cetacean Research and Management. 10(1):

34 Tregenza, N.J.C. and Collet, A Common dolphin Delphinus delphis bycatch in pelagic trawl and other fisheries in the northeast Atlantic. Rep. int. Whal. Commn 48: Tongnunui, S., A. Wattanakornsiri, K. Pachana, F. W. H. Beamish, and S. Tongsukdee Preliminary investigation of Irrawaddy dolphin (Orcaella brevirostris) in the Bangpakong estuary, inner gulf of Thailand. Environment and Natural Resources J. 9 (2): Wang, J.Y. & Reeves, R Neophocaena phocaenoides. In: IUCN IUCN Red List of Threatened Species. Version < WCS/BCDP Educational outreach, training and consultations in the three wildlife sanctuaries for freshwater dolphins in the Sundarbans, Bangladesh. Background document prepared by the Wildlife Conservation Society s Bangladesh Cetacean Diversity Project, Khulna, Bangladesh. 33

35 VII. Appendices Appendix 1: Handbook for a dolphin assessment in the Peam Krasop Wildlife Sanctuary, Cambodia (provided overleaf). Appendix 2: Names and affiliations of the Peam Krasop Wildlife Sanctuary dolphin survey team. Survey participants Position and affiliation 1. Mr. Lieng Saroeun Vice Chief of Fisheries Conservation Division 2. Mr. Hun Marady Deputy Director of Department of Environment, Koh Kong 3. Mr. Oul Rann Director of Peam Krasop Wildlife Sanctuary, Koh Kong 4. Mr. Chey Chenda Deputy Office of Administration, Department of Environment, Koh Kong 5. Mr. Thiv Keanthav Office Chief of Public Communication and International Cooperation, Koh Kong 6. Mr. Vong Dara Deputy Chief of Village II of Peam Krasop Commune 7. Mr. Heng Suy Representative of Koh Kapik Community Protected Area 8. Mr. So Sokha Peam Krasop Wildlife Sanctuary Ranger 9. Mr. Chhourn Oun Representative of Beoung Kachhang Community Protected Area 10. Mr. Nou Ngoy Deputy of Fisheries Division of Peam Krasop, Kong Kong 11. Ms. Saisunee Chaksuin Dolphin Conservation Coordinator, IUCN 12. Mr. Lou Vanny MFF Program officer, IUCN Cambodia 13. Mr. Sun Kong BCR Field Coordinator, IUCN Cambodia 14. Mr. Brian Smith Director Asian Freshwater and Coastal Cetacean Program, Wildlife Conservation Society 15. Mr. Noy Boem Boat Driver 34

36 Appendix 1. HANDBOOK FOR A DOLPHIN ASSESSMENT IN THE PEAM KRASOP WILDLIFE SANCTUARY, CAMBODIA Prepared by Brian D. Smith (bsmith@wcs.org) Ocean Giants Program, Wildlife Conservation Society Photo captions: Irrawaddy dolphins Orcaella brevirostris (top) and Indo=Pacific humpback dolphins Sousa chinensis (bottom). Photographs taken by WCS Bangladesh Cetacean Diversity Project.

37 TABLE OF CONTENTS CHAPTER 1. SIGHTING AND IDENTIFYING CETACEANS 3 CHAPTER 2. GENERAL PROCEDURES FOR SIGHTING SURVEYS OF CETACEANS 7 CHAPTER 3: DOUBLE COUNTS FROM INDEPENDENT TEAMS AND DISTANCE-DIVE TIME MODELS 11 CHAPTER 4. LINE-TRANSECT SURVEYS IN COASTAL WATERS 13 CHAPTER 5. PHOTOIDENTIFICATION 20 CHAPTER 6. USING A GLOBAL POSITIONING SYSTEM 29 CHAPTER 7. INVESTIGATING ENVIRONMENTAL PARAMETERS 34 CHAPTER 8. INVESTIGATING FISHING GEARS 36 CHAPTER 9. DOLPHIN CARCASS EXAMINATION AND SAMPLING PROTOCOL 37 LIST OF FIGURES Figure 1. Illustration of typical searching pattern for line-transect surveys for dolphins. 7 Figure 2. Single randomly placed transect line. Six dolphins were detected at distances X 1, X 2. X Figure 3. Conceptual basis for line transect sampling. 13 Figure 4. Examples if the line-transect detection function g(y). 14 Figure 5. Dolphin population with a gradient density is sampled using transect lines oriented perpendicular to the shore. 16 Figure 6. Perpendicular distance X is calculated according to r * sin (ϴ), where r =estimated radial distance to dolphin group. 17 Figure 7. Illustration of reticle scale used to calculate radial sighting distances. 18 Figure 8. Mark categories and wound classifications used for humpback dolphins. 23 Figure 9. Screen shot from ACDSEE of marks assigned to humpback dolphin individuals. 24 Figure 10. Illustration of GPS satellites orbiting the earth and how triangulation provides accurate information on the position of the GPS receiving devise. 29 Figure 11. Illustration of the minimum body measurements to be taken from a dolphin carcass. 39 Figure 12. Illustration on how to determine the sex of a dolphin. 40

38 CHAPTER 1. SIGHTING AND IDENTIFYING CETACEANS SIGHTING CETACEANS Cetaceans are frequently sighted after being alerted by cues - e.g., water disturbances caused by submerged or shallow-surfacing animals, fish driven to the surface by foraging dolphins, the presence of circling or diving birds. All cues need to be confirmed by direct observation of animals before being recorded as a sighting. Upon closer inspection, some cues will turn out to have been caused by something other than dolphins (e.g., fish surfacing, ducks diving). Observers should not to be shy about alerting other members of the survey team when a cue has been noted. With some species, the researchers will only observe a few surfacings. Also, many dolphins are fast swimmers so it will not always be possible to see the animals close up. It is important to be familiar with the features of dolphins known or thought to occur in the region before conducting surveys. A good pair of binoculars is essential. IDENTIFYING CETACEANS The identification of dolphins at sea is difficult and requires close attention to small details that may be visible for only a brief moment. Under no circumstances should researchers guess at identifications. All identifications should be accompanied by a detailed description of the observed characteristics and a drawing - artistic ability is helpful but not necessary. Species we will probably see in Peam Krasop and adjacent coastal waters include: Irrawaddy dolphin Orcaella brevirostris Distinctive characteristics Irrawaddy dolphins have a blunt head with no visible rostrum. The dorsal fin is small, triangular to slightly falcate with a rounded tip, and positioned slightly behind the mid-back. The neck is flexible and a neck crease may be visible. Flippers are large with curved leading edges and blunt tips. A U-shaped blowhole opens to the front, the opposite of most dolphin species. Adults range from m and length at birth is about one meter. The animal is gray overall with a generally lighter abdomen. 2

39 Behavior Irrawaddy dolphins are normally found in small groups of less than six animals but sometimes as many 15 or even more. The dolphins are not particularly active but they do make low leaps when disturbed. In inland channels Irrawaddy dolphins tend to be found in deep pools downstream of channel confluences and meanders, and upstream and downstream of islands. Indo-Pacific humpbacked dolphin Sousa chinensis Distinctive characteristics Indo-Pacific humpbacked dolphins have a robust body, well defined beak, and a dorsal fin that sits on a hump on back. The color pattern varies with large amounts of pinkish white coloration and blue spotting on older animals. Some older dolphins can become all pinkish white. 3

40 Behavior Group size is generally less than 10 individuals although a group up to 55 has been reported. These dolphins occasionally exhibits acrobatic behavior but they rarely leap while swimming. They are generally not known to bowride. Finless porpoise Neophocaena phocaenoides Distinctive characteristics Finless porpoises are slightly smaller than Irrawaddy dolphins. As the name implies they have no dorsal fin. The body is dark grey, slender and torpedo shaped with a rounded head and no beak. The tail stock is narrow and flukes concave. The pectoral fins are relatively large with rounded tips. Behavior Finless porpoises generally surface low and fast showing little of their body appearing like a tire tube popping up quickly on water surface. Group sizes are generally 1-12 individuals. They tend to shy away from vessels and never bowride. Species we may see in coastal waters include: Indian Ocean bottlenose dolphins (Tursiops aduncus) The Indian Ocean bottlenose dolphin has recently been recognized as a distinct species from the common bottlenose dolphins. Both species appear similar but Indian Ocean bottlenose dolphins are smaller, have a longer snout. Adults exhibit blue spotting on the throat and belly. The species inhabits coastal waters in the northern Indo-Pacific. 4

41 False killer whale (Pseudorca crassidens) False killer whales are large (5-6 m) slender dolphins with a rounded overhanging forehead and no beak. The dorsal fin is falcate with a rounded tip. The flippers have a characteristic hump on the leading edge. The species can easily be confused with melon-headed and pygmy killer whales. The flippers are probably the best way to distinguish them. The species is found in temperate and tropical deep offshore waters. Bryde's whale (Balaenoptera edeni) This whale is difficult to distinguish from the sei whale (Balaenoptera borealis) but can be identified from the three prominent ridges on its rostrum. Adult animals can be up to 15.5 m long, although a distinctly smaller form has been described for some regions in Asia. The dorsal fin is tall and falcate with a pointed tip that rises abruptly from the back. The height of the blow is variable and this whale often exhales underwater and surfaces with little or no blow. 5

42 CHAPTER 2. GENERAL PROCEDURES FOR SIGHTING SURVEYS OF CETACEANS INTRODUCTION Survey methods must be standardized to estimate abundance and make science-based recommendations for management. Credible estimates of absolute abundance are important for formulating conservation strategies for highly endangered populations or species. A major challenge in assessing the abundance of dolphins in mangrove channels is the complex channel morphology of rivers and estuaries. This concentrates dolphin distribution in microhabitats associated with specific hydrological features and limits the ability of survey vessels to follow random or systematic search patterns. SEARCH EFFORT The quality of data from dolphin surveys depends on observers searching for dolphins in a conscientious and consistent manner. It is essential to accurately record data on search effort and variables affecting search efficiency (e.g., sighting conditions, length of watches). Three observers will search for dolphins at all times while on-effort (i.e., actively searching for dolphins along the transect line and recording effort and sighting data), one stationed on each the port and starboard sides, searching with handheld 7x50 binoculars and naked eye from the beam to about 10 past the bow, and one in the center searching by naked eye in about a 20 cone in front of the bow. The center observer will also serve as the data recorder. Observers will rotate through the three different positions every 30 minutes followed by at least an hour of rest before switching teams (Figure 1). The vessel captain, crew and resting observers must keep dolphin sightings a secret until the on-effort observers detect them or the entire group passes behind the vessel. A Global Positioning System (GPS) is used to guide the survey vessel and determine its speed, course and the distance covered along transect lines. Data including vessel speed, course, trip distance, and sighting conditions are recorded on a standardized effort log. Data entries are made after all observer rotations and any substantial change in vessel course or sighting conditions. A relatively constant survey speed is maintained of generally 10 km hr. Consistency with respect to search effort, sighting procedures and data recording is vital. Effective communication between the observers on watch and the vessel helmsman is vital to ensure that transect lines are followed, to direct the vessel to dolphin sightings for 6

43 identifying the species and estimating group size, and to direct it back to the transect line for continuing the survey. Searching should optimize detection of dolphins near the transect line. The probability of sighting animals on the transect line can be increased by using binoculars, surveying at a slower speed, and employing a dedicated observer to watch the transect line. Movement by dolphins away or towards the transect line in response to the survey vessel will bias estimates of sighting distance. Binoculars can help ensure that dolphin groups are detected far enough away before from the vessel before any responsive movement can be made. Figure 1. Illustration of typical searching pattern for line-transect surveys for dolphins. 7

44 USING BINOCULARS Before the survey begins observers should adjust the focal settings on each ocular to an object at about 500 m distant. This is done to achieve the best focus for each eye. Remember these settings so that you can quickly adjust each ocular to its proper position. 1. Adjust the fit of the binoculars to the distance between your eyes. The setting is correct, if you see one clear image while looking through both openings at the same time. 2. Close your left eye and turn the focus ring of your right eye-hole until the picture appears focused. 3. Repeat the same for your left eye by closing your right eye and adjusting the focus ring on the left hole. 4. After completing your adjustment, check the settings on the focus rings and remember it. You will need to adjust the binoculars before every use. SIGHTING CONDITIONS Surveying when environmental conditions are poor can lead to underestimating abundance. Rain, high winds, sand or dust storms, sun glare, and severe heat can impair sighting efficiency. If data are being used for estimating abundance survey effort generally stops when sighting conditions are significantly compromised. A careful record is kept of sighting conditions to assess their effects on detection rates and estimates of abundance (Table 1). Wind, glare, or rain/fog conditions will be given codes of 0, 1, or 2, corresponding to good (no effect on sighting conditions), fair (small effect on sighting conditions), and poor (large effect on sighting conditions), respectively. More specifically, for wind, code 0 means that the water surface is glassy or has only small ripples; code 1 is small waves but no white caps; code 2 is larger waves with whitecaps. For glare, code 0 is no glare, code 1 is severe glare (view completely obscured) covering less than 10% of the field of view or slight glare (view only partially obscured) covering less than 50% of the field of view, code 2 is severe glare covering more than 10% of the field of view or slight glare covering more than 50% of the field of view. For rain/fog, code 0 is no fog or rain, code 1 is fog or rain obscuring no more than 10% of the field of view or partially obscuring no more than 50% of the field of view, and code 2 is fog or rain obscuring more than 10% of the field of view or partially obscuring more than 50% of the field of view. CETACEAN SIGHTINGS When dolphins are sighted (1) immediately take and record a waypoint of the geographic position on a GPS; (2) record the time from the GPS; (3) record the observer who first detected the dolphin group and the estimated radial distance and angle to the animals; (4) record best, high, and low estimates of group sizes (see below); (5) alert the environmental 8

45 team that the vessel is approaching a dolphin sighting; and (6) record a second waypoint at the estimated geographical position (or as close as the vessel comes to this position along the survey path) where the dolphins were located at the time of sighting. ESTIMATING GROUP SIZES Group sizes should be estimated using best, high, and low estimates. High and low estimates are used to reflect the confidence of observers in the accuracy of the best estimate. The low estimate should be considered a minimum count and the high estimate a maximum count. Identical best, high, and low estimates indicate a high level of confidence in the best estimate. A low estimate of zero can be used to reflect the possibility of double counting a sighting. Distinctive physical characteristics of individual animals (e.g., scarring, pigmentation patterns, length of rostrum relative to the height of melon, and body size) and the location of surfacings relative to shoreline features and other animals can be used to assist observers in making group size estimates. Estimates should be agreed upon by a consensus of the research team. If observers do not agree, the lowest estimate by any team member should be used for the low, the highest estimate for the high, and the best estimate by either the observer with the most experience or the observer who first sighted the animal(s). 9

46 CHAPTER 3: DOUBLE COUNTS FROM INDEPENDENT TEAMS AND DISTANCE-DIVE TIME MODELS PRECISION AND SIGHTING BIASES A measure of precision (i.e., a coefficient of variation or CV) is an extremely important component of abundance estimates. The CV tells you the upper and lower boundaries of your abundance estimate. An abundance estimate with a low CV (indicating high confidence) is much more valuable than the same estimate with a high CV (indicating low confidence). Unlike density sampling techniques direct count surveys do not have a built-in mechanism for calculating a CV. Estimating the abundance of dolphins from direct count surveys is further complicated due to the unknown number of animals that are missed due to sighting biases. Sighting biases are related to dolphin availability (most animals are underwater at any given time, and, when they are at the surface, they generally show little of their body) and observer perception (all surfacings are not necessarily noted because observers may be inattentive, distracted, fatigued, or focused on a different location). Estimates can also be biased upward if, when estimating group size, multiple surfacings by the same individuals are attributed to more animals than are actually present. Clearly defined methods to reduce bias and quantify variability should be incorporated into survey designs. During our survey of inland waterways we will investigate and correct sighting biases using double counts by independent teams and dive-time distance models. DOUBLE COUNTS BY INDEPENDENT TEAMS We will conduct the survey in mangrove channels using two independent teams on different vessels separated by one to two kilometers following predetermined track lines uploaded into the GPSs of both vessels. The two vessels will not be in visual contact and observers will avoid alerting the other team about dolphin sightings. The vessels will coordinate their positions through two-way radios. The survey protocol will be the same for both teams. When dolphins are sighted, the distance and relative angle to the group will be estimated and a GPS waypoint recorded. The latter is termed the detection position. This vessel will remain on course and pass by the group while proceeding downstream. When the group is located perpendicular to the dolphin group, a second position will be taken which is termed the location position. The second vessel will do the same except that it may stop at the location of dolphin sightings to take photographs for identification purposes. If the second vessel stops the observers should call the first vessel on the two-way radio so that they can also stop. After photographs have been taken the observer on the second vessel should call the first vessel again to inform them to resume the survey. 10

47 All sighted dolphin groups will be classified as matches if they were seen by both survey vessels, or unique if they were missed by one of the observer teams. A GIS Program will be used to measure the distance between location positions of sightings made by both boars Obvious clumping of distances will be used to guide the selection of an appropriate distance threshold to classify groups as matched. A factor to correct for perception bias (the proportion of visible animals that are missed by observers) will then be calculated using a Chapman s modified Lincoln-Petersen mark-recapture estimator (Chapman 1951): ( nf + 1)( nr + 1) G c = 1; ( m + 1) fr with associated coefficient of variation CV c : CV c = Vc Gc where n f = the total number of groups detected by the front observer team, n r = the total number of groups detected by the rear observer team, and m fr = the total number of groups detected by both teams (matches or recaptures). The correction factor for groups missed can be calculated G c /n p, and the corrected estimate of the total number of groups can be calculated by multiplying this parameter by the total number of on-effort sightings made by the front observer team. This number will then be multiplied by the mean group size for estimating the abundance of individuals in the survey area A i. DIVE-TIME AND SIGHTING DISTANCE MODELS Periodically we will stop the vessel and record information on dive times. Using a stopwatch, observers will record dice times. Dive times will be recorded for groups, not individuals. Dive times are defined as the interval when no animals are visible at the surface. Using the distance estimates from dolphins sighted during our survey and the mean vessel speed, we can calculate the probability that the animals will be available to be seen at the surface at various distance intervals and develop an appropriate correction factor if needed. 11

48 CHAPTER 4. LINE-TRANSECT SURVEYS IN COASTAL WATERS Line-transect surveys allow for the estimation of density. Density and population size are related according to the formula: N = D * A, where D = number of animals / area, A = Area, and N = Population size The critical data are distances to the animals (individuals or clusters) from a transect line that has been placed randomly in relation to their distribution (Figure 2). A large proportion of animals will not be detected during visual surveys but density sampling allows an accurate estimation of abundance if certain assumptions are met - either in the field or during the analysis. Figure 2. Single randomly placed transect line. Six dolphins were detected at distances X 1, X 2. X 6. In practice several lines would be used to sample the population. 12

49 The ability to detect animals usually decreases with increasing distance from the transect line. A histogram of sighting distances can be used to estimate the number of animals left undetected (Figure 3). Figure 3. Conceptual basis for line transect sampling: (a) expected number of dolphin groups detected in eight distance classes if no groups are left undetected; (b) theoretical data illustrating the tendency to detect fewer groups at greater distances; and (c) the estimated proportion of undetected groups can be estimated from the numbers represented by the area above the curve (in gray) created by the decline in sightings as a function if distance. Figure from Buckland et al

50 The underlying theory of line-transect surveys is the concept of a detection function, g(y) = probability of detection at distance y (Figure 4). A series of estimates of the perpendicular distances to dolphin groups are modeled with mathematical curves. The one with the best fit is chosen and used to estimate the number of undetected groups as shown above. Figure 4. Examples of the line-transect detection function g(y). Function b is truncated a w and thus takes a zero value for all y>w. Functions with shapes similar to a, b, and c are common in distance sampling. Function d usually results from poor survey design and is problematic. Figure from Buckland et al BASIC FORMULA Dolphin density (D) and its associated coefficient of variation (CV) can be estimated using the program DISTANCE v3.5 (available for free at according to the line-transect formula in Buckland et al. ( ): n fˆ(0) Ê(s) Dˆ = 2L vâr (n) vâr [fˆ(0)] vâr [Ê(s)] C Vˆ = D * n [fˆ(0)] [Ê(s)] 1 Buckland, S.T., Anderson, D.R., Burnham, K.P, Laake, J.L., Borchers, D.L. and Thomas, L Introduction to Distance Sampling: Estimating the Abundance of Biological Populations. Oxford University Press Inc., New York. i-xv+432pp. 14

51 where n = number of on-effort sightings, f(0) = probability density value at zero perpendicular distance, E(s) = unbiased estimate of group size, L = length of transect lines surveyed, and var = variance. ASSUMPTIONS Close attention must be paid to the following assumptions during survey design, search effort and data analysis: Transect lines are random with respect to dolphin distribution. All sightings on the transect line are detected although correction factors can be applied. The animals do not move in response to the boat before they are detected. The estimated distance to the animals from the transect line is estimated without bias. Sightings are independent events. Animals are not double counted along a single transect line. SURVEY DESIGN Designing Transect Lines A good map is essential. Transect lines must be placed perpendicular to environmental contours and have random starting points (Figure 5). Transect lines should be placed at a distance far enough apart to avoid an object being detected on two neighboring transects. Sample Size and Transect Line Length If a sample is too small then little information is available for estimating density and precision is low. This consideration determines the amount of survey effort needed to obtain a reasonably precise estimate of population size. The total length of transect lines depends on the precision required and encounter rates. A pilot survey can help researchers design surveys that will achieve a large enough sample size so that the estimates of abundance are meaningful. Distance Estimates Line transect surveys require an estimate of the perpendicular distance between the transect line and the dolphin group. Perpendicular distances are calculated according to the estimated sighting or radial distance (r) and the sighting angle Ø relative to the vessel heading according to r * sin (Ø) (Figure 6). Rounding distance estimates should be avoided. Distance estimates should be made to the first animal detected in the group. 15

52 Observers can be trained to improve their distance estimates by estimating the distance objects on the water with feedback from distance measurements made with a laser range-finder. Distance estimates can be calibrated according to tests of distance estimation error using laser range-finder measurements to floating objects. Figure 5. Dolphin population with a gradient density (i.e., habitat preference for nearshore waters) is sampled using transect lines oriented perpendicular to the shore. 16

53 Figure 6. Perpendicular distance X is calculated according to r * sin (ϴ), where r = estimated radial distance to dolphin group. DATA COLLECTION Group Size Estimates Small groups can be counted but larger groups will need to be estimated. To avoid double counting animals in small groups pay attention to individual features that can help you determine if you are seeing the same animal on the next surfacing. To avoid missing dolphins in small groups make sure to spend a long enough time with the animals so all individuals are available on the surface to be counted. For estimating the size of large groups, it is best to count ten dolphins to get a visual image of what 10 dolphins look like and then scan across the group counting by 10s. A common set of procedures for line transect surveys are that: When a dolphin group is detected a GPS waypoint is immediately taken and information recorded on the waypoint number, distance estimates to the dolphin group, relative angle to the dolphin group. The relative angle can be either estimated directly or derived from the difference between the compass bearing in the binoculars compass and the vessel bearing according to the GPS set to magnetic north. These data are time dependent and must be recorded as close to the time of sighting as possible. If a horizon is visible reticle readings in the binoculars can be used to obtain a more precise distance estimate (Figure 7). Searching effort is suspended at the time of the sightings and the vessel turns towards the dolphin group to obtain a more accurate estimate of group and sometimes to take photographs of individual dolphins for photo-identification purposes. Other data should then be recorded on the species identification (or to the lowest taxonomical/descriptive group (e.g., small unidentified dolphin or porpoise), group size, me of observer who first sighted the dolphin group and estimated the sighting distance and angle, Beaufort sea-state, and other information on dolphin behavior (e.g., 17

54 movements, grouping, activity, social interactions), life history (percentage calves, age structure), environmental conditions (salinity, depth, temperature). After finishing these tasks, the vessel returns while off-effort (i.e., not actively searching for new dolphins) to the position where it left the transect line, while the observers track the movements of the dolphin group to avoid double counting them when search effort is resumed. Figure 7. Illustration of reticle scale used to calculate radial sighting distances. 18

55 CHAPTER 5. PHOTOIDENTIFICATION GENERAL Photo-identification uses naturally occurring, unique marks to identify individuals. Advantages: Permanent record of individuals. Provides information on behavior and abundance. Does not required handling of the animals. Relatively inexpensive compared to artificial marking or telemetry techniques. Disadvantages: The close presence of a boat can alter the animal s normal behavior. Not all individuals in a population can be photoidentified using natural marks. The analysis is limited to those individuals that can be photographed and individually recognized. Need experienced photographer and good equipment. Marks are often similar among individuals and can change over time. EQUIPMENT The primary piece of equipment in the field is a 35mm SLR camera capable of fast shutter speeds, and a telephoto lens (e.g., 300mm). A dedicated hard drive should also be used to store the photo images. FIELD METHODS Photographs are taken of the dorsal fins of the animals at a perpendicular angle to the body of the dolphin. Boat operators should approach dolphin groups slowly, and every effort should be made to navigate the boat parallel to the group s direction of travel. Every attempt should be made to obtain a high quality photograph of the dorsal fin of every dolphin present in a group. PHOTO-ID DATABASE Each day of photo-identification effort should be considered a single session. Multiple captures (or photo-identifications) of an individual dolphin during a single session (day) should be counted only once but make sure to store this info separately for home range analysis. Each photograph that contains one or more dorsal fin images should be evaluated according to the quality of the image. Quality should be considered poor if the image of the dorsal fin 19

56 is insufficiently clear for identifiable marks to be discerned. These photographs should be removed from the photo-database. Sharpness/focus, contrast/lighting and angle of the fin in relation to camera are considerations for deciding on the quality of the picture. Be sure to keep a careful record of the total number of good quality photographs with marks on the dorsal fin that would allow the dolphin to be identified and the total number of good quality photographs without marks on the dorsal fin. This can be used to identify the proportion of unmarked individuals and correct mark-recapture estimates (see below). Each good photograph should be named according to day month year (initials of photographer) and serial number (e.g., 01Oct13 (BDS) 1). The remaining photographs should be edited as needed to improve their quality (i.e., adjusting the contrast and fill light). Cropped images of each identifiable dorsal fin should be extracted. PICASA is a good image editing software to accomplish this task. Cropped images should only include a small area of water to maximize resolution of the dorsal fin when zooming in. However, keep the complete visible part of the dolphin s body in the cropped photo to look for wounds from fishery and shark interactions, parasites, skin disorders, emaciation etc. Whenever possible, photographs of calves should be cropped with the accompanying adult. Using the PICASSA software you can assign an additional serial number to each image name indicating the number of cropped photos from the original image. After photo-editing you will end up with windows folders containing the cropped dorsal fin images for each day of your field work. These folders can be opened up in the ACDSEE database which remembers the Windows Operating System s folder path (e.g., F:\Swatch Project\id photos\type Specimen). After this step it is vital not to move the image files in your hard drive. Make sure you have enough memory to handle large files. Although it is possible to move the database between hard drives and computers the connections between files must be inputted again. This is a tedious process especially as the size of the data base increases. 20

57 Above is a screen shot from ADCSEE. These images are from one day of photo id effort on Indo-Pacific humpback dolphins. In the category tree on the left subcategories were created under each of ACDSEE s default categories (Albums, People, Places, and Various) which cannot be changed. A category is created by checking the box beside the category with a white arrow to each image for that day and then naming it. Each image of the same individual photographed that day is assigned to another category with a serial number and specific name given to each individual/category. Images that do not have sufficient marks to be photoidentified are assigned to a clean photo category. The best image of each individual is assigned to a category 1 of each (circled in red above). By double clicking this category, you can look at the single best image of each individual. At the end of this workflow all your photos should have a blue tag above the image (circled in green above). The next step is to copy all photos for each individual to a folder labeled with a serial number or name assigned to that individual. You will end up with something like the image below. 21

58 The best photographs of each individual from each day are then compared to the best photographs of previously identified individuals in the photo-catalogue which are also organized in their own folders. Each match of a photograph with an existing individual from the catalog is considered a recapture. All matched photographs are then copied to the master folder for that individual. After all the possible recaptures are identified, new individuals with clear diagnostic marks are assigned a unique identification number and attributes for dorsal fin and body marks as per the criteria in Table 1. The search for photographic matches (or recaptures) is made more efficient by assigning mark attributes to each newly identified dolphin (Figure 8). Individuals in the photocatalogue can then be filtered by mark types using the ACDSEE software (Figure 9). This allows matching efforts to focus on a smaller subset of individuals exhibiting similar diagnostic features. Only dorsal fin marks should be used to confirm captures or recaptures, although body wounds can be used to narrow the identification search. An example is given below of mark attributes on the category tree on the left. 22

59 Table 1. Criteria used to categorize dorsal fins according to mark types and their location. Mark Type Nicks (mark whose opening is 1/10 th or smaller of the straight fin height) Notches (mark whose opening is greater than 1/10 th to 1/5 th of the total straight fin height) Gouge (mark whose opening is greater than 1/5 th to 1/3 rd of the total straight fin height) Large fin wound (opening that covered more than 1/3 rd the total straight fin height) Dorsal fin bend Body wound Suspected shark bite Parasite Location on dorsal fin or body Trailing edge top third, middle third, bottom third, tip or leading edge Ibid Ibid Trailing edge or leading edge Dorsal fin tip Anterior of dorsal fin tip or posterior of dorsal fin Dorsal fin, anterior of dorsal fin tip, posterior of dorsal fin Ibid Figure 8. Mark categories and wound classifications used for humpback dolphins. 23

60 Figure 9. Screen shot from ACDSEE of marks assigned to humpback dolphin individuals. This allows researchers to filter groups of similar marks and makes the photo-id process much easier because you do not need to search through the entire photo-catalog for matches. Storage and preservation of archived data and images should be carefully considered. Keep more than one back-up of electronic databases and digital images in separate locations. MARK RECAPTURE MODELS FOR ESTIMATING ABUNDANCE Photoidentification can provide estimates of population size using mark-recapture methods. The methods are based on the principle that if a proportion of the population is marked (or photoidentified) and returned to the original population then the proportion of marked (or photoidentified) individuals in the second sample would be the same as was initially marked in the total population. N/M = n/m or N = Mn/m where M = number of individuals photo-identified during the first sampling period, and n = the number of individuals photo-identified during the second sampling period m = the number of animals photo-identified during both surveys. More complex mark-recapture models are based upon multiple photographic sessions and take into account whether photographs are on the right or left side of the animal's body. There are two basic types of models to estimate population size from capture-recapture data: Closed population models that assume no births, deaths, immigration and/or emigration, and 24

61 Open population models that consider the events above. In general, closed population models are used for data collected over short periods of time while open population models must be used in long-term photo-identification studies. Closed population models One of the most widely used estimators in photo-identification studies of marine mammals is the Chapman s modified Lincoln-Petersen mark-recapture estimator (Chapman 1951): ( n1 + 1)( n2 + 1) A = 1; ( m + 1) 1,2 with associated variance V c (Seber 1970): V a = ( n1 + 1)( n2 + 1)( n1 m1,2)( n2 m1,2) 2 ( m1,2 + 1) ( m1,2 + 2) ; and coefficient of variation CV c : CV a = V c G c where n 1 = the total number of individuals identified during the first sampling session, n 2 = the total number of individuals identified during the second sampling session m 1,2 = the total number of individuals detected by both teams (matches or recaptures). A Chapman s modified Petersen model (without replacement) only considers the first sighting of an individual in the each study period no matter how many times the animal is re-identified. More sophisticated models take advantage of information in multiple reidentification of individuals during different This abundance estimate is for the number of individuals with identifiable marks so it must be corrected for the proportion of unidentifiable animals. This can be calculated from the proportion of indentified individuals in each sighting versus group size estimates or the proportion of clean fin versus identifiable photographs. 25

62 Open population models The most widely used model for open populations is the Jolly-Seber model. It provides estimates of population size for each sampling event, except the first and last, and estimates survivorship and recruitment for each sample with the same exceptions. The estimator derives from two equations: an estimate of the total number of marked animals in the population just before the ith sampling occasion (M i ), and a general form of the Petersen estimate for the ith sampling (N i ). M i = (s i z i / r i ) + m i and N i =M i n i / m i ni N i = n i [1 + (s i z i / r i m i ) Where N i = Total number in the population just before time i n i = number of animals caught in the ith sample s i = number of marked animals released after the ith sample m i = number of marked animals caught in the ith sample z i = number of animals caught before the ith sample which are not caught in the ith sample but are caught subsequently r i = number of marked animals released after the ith sample which are subsequently recaptured The assumptions of this model are: a) Every animal in the population (marked and unmarked) has the same probability of being caught in the ith sample, given that is alive and in the population when the sample is taken. b) Every marked animal has the same probability of surviving from the i th to the i th +1 sample and of being in the population at the time of the i th +1 sample, given that is alive and in the population immediately after the i th release. c) Every animal caught in the i th sample has the same probability of being returned to the population d) Marked animal do not lose their marks and all marks are reported on recovery e) All samples are instantaneous. Computer programs have been developed to calculate estimates of population size and other parameters such as survival and mortality. Software includes CAPTURE and MARK (available at and 26

63 Movement patterns, social structure and life history Based on re-identifications of individuals over time and space and information on geographic position, researchers can estimate home ranges, occurrence in different habitat types, and dispersal and migration patterns. Social structure is defined by the assumption that individuals in close proximity are affiliated. Using photo-identification, the strength of that affiliation is represented by the number of times they are identified together. The most common association index used in studies of dolphin social structure is the Half- Weight Index (HWI) HWI= 2a*b/(a + b) Where a = Total number of times individual a was seen, b = total number of times dolphin b was seen, and ab = total number of times dolphins a and b were seen together. This association index ranges from 0 (e.g. two dolphins that are never seen together) to 1 (e.g. two dolphins that are always seen together). For analyzing associations it is important to ensure that every effort is made to photograph all animals in the group. Otherwise associations will be underestimated. Long-term photo-identification studies accompanied by detailed sighting information can also provide data on sexual maturity, calving intervals, reproduction and life spans. 27

64 CHAPTER 6. USING A GLOBAL POSITIONING SYSTEM INTRODUCTION GLOBAL POSITIONING SYSTEM The Global Positioning System (GPS) is a satellite system used in navigation that allows you to determine your three dimensional position, velocity and time, 24 hours a day, in any kind of weather, anywhere on the globe (Figure 10).. The Global Positioning System (GPS) works on the basis of triangulation from satellites. Figure 10. Illustration of GPS satellites orbiting the earth (left) and how triangulation of the radio signals from the satellites provide accurate information on the position of the GPS receiving devise. Triangulation Each satellite broadcasts a message giving its name, its position and the precise time. The message is sent as radio signal, which travels at the speed of light (186,000 miles per second). The receiver calculates the distance to each satellite based on the time taken for the signal to reach it. There will be a time lag, directly proportional to the distance. Distance = speed x time. With three satellites, the exact position on the earth s surface can be calculated. This assumes no error - in fact there are many sources of error. This means that only an approximate position can be calculated from three satellites. 28

65 Perfect Time Satellites have an extremely accurate atomic clock on board GPS Receiver time is calibrated using the signals from three satellites. If receiver time is incorrect the three circles will not intersect. So it calculates which time it should read in order for the circles to intersect and then corrects its own time accordingly. USE OF A GPS GPS PAGES There are 6 pages on the GPS. o Satellite page o Position page o Map page o Compass page o Highway page o Route page We will not be using the highway page. Use the Quit key to move backwards through the pages and the Page key to move forwards. TURNING GPS ON AND OFF Press and hold Power key (for about one second) to turn the GPS receiver on Press Enter key to continue Press and hold Power key for 1 second to turn the GPS off SATELLITE PAGE Screen changes to Satellite page and is acquiring satellites. Battery status bar shows amount of battery power left. Sky map shows where satellites are located and identifies them by number. Satellite status graph shows which satellites are communicating with the GPS receiver. Three satellites are enough to determine your position; however, four or more produce a more accurate position (3D Nav). The satellite screen shows you the precision of your position depending on how many satellites it is receiving signals from. MAP PAGE Once enough satellites have been found, the GPS automatically changes to the Map page Press the Quit key to return to the Satellite page POSITION PAGE Shows your current position on the earth, in geographic coordinates (latitude and longitude). 29

66 It also tells you the current time and date, time of sunrise and sunset, altitude, speed over ground, average speed, and direction of travel. ROUTE PAGE Routes will be created in Mapsource and downloaded into the GPS (see below). To follow a route press the NAV key, then use the arrow key to highlight the route to be followed and press ENTER. COMPASS PAGE The compass page can guide you to a waypoint or along a route Use the GO TO function to navigate to a waypoint. If the arrow on the compass page points straight up you are going in the correct direction towards the waypoint or along the route. If the arrow points in another direction turns towards the arrow until it points up. RECORDING A WAYPOINT A Waypoint is your geographic position recorded into the memory of the GPS. For each stored waypoint the position, time and name of the location are automatically recorded. During the dolphin survey waypoints will be recorded at the beginning of survey effort, at the end of each leg (a certain time period of survey effort) From the Position or Map page, press the Enter key to record a waypoint at your current position. Make sure to hold the key down until the view screen changes to the Waypoint Screen. To save the waypoint you need to push the Enter Key a second time. This time the button should be pushed very quickly or you will record another new waypoint WAYPOINT DETAILS To see details of a waypoint: Press Menu twice to go to Main Menu Select Waypoints and press Enter Select the waypoint ID you want to see Press Enter The waypoint details are shown and can be edited here STARTING YOUR TRIP Each segment of the survey (normally one day) is a separate Trip for the GPS. If the Trip Computer is reset at the beginning of each day, the GPS will give details for that days survey including the total distance traveled, average speed, maximum speed and total trip time. 30

67 SETTING THE TRIP METER Go to the Main Menu page (by pressing the Menu key twice) Highlight Trip Computer (by using the Rocker Keypad) Then press Enter o Press the Menu Key o Highlight Reset All o Press Enter The trip odometer, time and average speed are now reset to zero SET UP THE TRACK FUNCTION The Track function records the path that the GPS has traveled into the GPS memory. For each survey day, we will record the track. The track, along with all the waypoints, will be downloaded from the GPS onto a laptop computer at the end of each day Go to the Main Menu page (by pressing the Menu key twice) Highlight Track Log (by using the Rocker Keypad) Then press Enter Highlight Active Log and press Enter Note Memory box - this is the amount of memory used Highlight Clear and press Enter to reset the track log Press the Menu Key Highlight Setup Logging Press Enter Set Record Mode to Fill Highlight Record Mode box Press Enter Select Fill, then press Enter Set Interval to Resolution Set Interval Value to 100 m LINKING A GPS RECEIVER WITH A COMPUTER A GPS has a relatively small memory, so it is necessary to transfer the data to a computer. Each brand of GPS receiver has its own interfacing software. For Garmin that software is called MapSource. This is a simple program designed for data manipulation and presentation as well as storage. It is possible to store both Waypoints and Tracks in MapSource. These can then be imported into other programs such as Microsoft Excel or ArcView for more sophisticated analysis. MapSource includes a base map, similar to the one on the GPS, which includes basic features such as major roads, coastlines, rivers and towns. As the user changes the scale on the map and zooms closer in or further out, the level of detail displayed increases or decreases correspondingly. 31

68 Using MapSource it is possible to: View data on a simple map background and print a basic image of your tracks and waypoints. Create, edit or delete waypoints Create, edit or delete tracks or portions of tracks. Measure distances between selected points Change the format of the position (e.g. from Latitude Longitude to UTM coordinates). 32

69 CHAPTER 7. INVESTIGATING ENVIRONMENTAL PARAMETERS INTRODUCTION Understanding the environmental characteristics that characterize dolphin habitat is critical for developing effective conservation strategies. This information can be used to identify hotspots of dolphin occurrence, predict seasonal distribution patterns, and monitor longterm changes in the aquatic environment that may affect the survival of dolphin populations. ENVIRONMENTAL PARAMETER DATA COLLECTION PROCEDURES During our survey a two-person environmental parameter (EP) team will record environmental data on a standardized data form (Appendix 4) every two-km and at the location of dolphin groups (only in the vessel turns off effort towards the dolphins) to collect data on salinity, turbidity, depth, and temperature. At environmental sampling locations the EP team will: 1. Record a GPS waypoint on the depth sounder (see below). 2. Collect a water sample with the container attached to a line. 3. Measure temperature and salinity reading with the WP-84 Temperature-Salinity- Conductivity meter. 4. Measure turbidity with the portable turbidity meter. Depth A depth sounder consists of two components: 1. A Transducer the component attached to the bottom of the boat that transmits and receives the signal; and 2. A Sounder Unit interprets and presents the signal in a visual format. The transducer transmits sound in a cone shaped pattern. When a transmitted sound wave strikes an underwater object such as the bottom of the sea or river, or a fish or dolphin the sound is reflected back to the transducer. The transducer collects the reflected sound waves and sends the information back to the GPS unit to be displayed on the chart The transducer is fixed to the bottom of the boat, preferably in a location where it experiences minimum turbulence. Turbulence attenuates the transmitted signals and stops the transducer from obtaining useful information. Different transducers emit sounds in different size cones; the larger the cone angle, the larger the coverage area at a given depth. A wide cone angle transducer works best in shallow water as the wide cone provides a large area of coverage but a decreased ability to reach deep depths and give good bottom resolution. A narrow cone angle transducer is better suited to deep water. The narrow cone angle provides a smaller viewing area (compared to a wide cone angle transducer at the same depth), but with improved bottom resolution and a smaller dead zone. 33

70 Information is passed from the transducer to the sounder unit by a cable. The sounder unit receives the data and presents it as a sonar image of the water beneath the boat. This image is moving from left to right as the boat moves forwards. Items appear as they pass under the transducer. Items with the strongest sonar return will be displayed in darker colors whilst those with a weaker return are displayed in lighter gray. Typically the bottom will be the darkest line displayed as this solid substance reflects a strong signal. Fish and other underwater items reflect a weaker signal and are displayed by a variety of userdefined signs. Using the depth sounder, it is possible to obtain an image of both bottom hardness and structure. When the sonar waves are reflected, a hard bottom will return a stronger signal than a soft bottom. This is displayed on the sonar image. A hard bottom will be displayed as a dark gray line with a wide white line beneath. A softer bottom will be shown as a dark gray line with a narrow white line beneath. Turbidity Turbidity will be measured with a portable turbidity meter from a water sample taken at the 30-minute data collection interval and for all dolphin sightings. 1. Rinse and clean an empty turbidity tube with a portion of the sample and shake out all liquid. Fill the turbidity tube to the neck by carefully pouring the sample down the side of the tube to avoid creating bubbles. Cap the tube and wipe it dry with a clean lint free tissue. 2. Open the lid of the turbidity meter. Align the indexing arrow on the tube with the indexing arrow on the meter. Insert the turbidity tube into the chamber. 3. Close the lid. Push the READ button. The turbidity in NTU units will be displayed within 5 seconds 4. Repeat this procedure three times. We will use the median reading. 5. To turn the meter off, hold the READ button down for at least one second. Release the button when OFF is displayed. 34

71 CHAPTER 8. INVESTIGATING FISHING GEARS While searching for dolphins we will also use a strip transect method to estimate the density of fishing vessels and classify each according to type. A separate observer will stand watch and record sightings of active fishing vessels (i.e. fishing gear deployed and not just underway or on drift) when they are located perpendicular to the beam of either side of the vessel. On a standardized form, we will record data on the geographic position, number and type of fishing vessel(s), and estimated distance from our position (Appendix 5). Classifications will need to be modified for Cambodian fishing gears but an example of gears from others areas in Asia includes: Shrimp trawlers (SHT) horizontal booms deployed on each side with one or more trawl nets deployed; Stern trawlers (STT) trawl nets deployed from the rear; Hang trawlers (HT) horizontal booms deployed on each side with vertical booms attached to the end of the horizontal ones and trawl nets deployed from these; Pair trawlers (PRT) two vessels traveling parallel about one km apart with trawl nets deployed from the stern; Gill netters (GNT) surface nets deployed with flags and buoys visible; Squid jiggers (SQJ) vessels with many large lights for attracting squid; Purse-seiners (PSS) large vessels with smaller skiff and net for encircling fish; Long liners (LLR) long fishing lines with many hooks deployed from the stern of the vessels and buoys visible at the ends; Other (OTH), with a description provided. The width of the survey strip will be determined post-hoc according to the distance that encompassed all observations of that vessel type. We will assume that all fishing vessels were observed in the survey strip (i.e. a complete census) and estimate fishing vessel density according to the total number of vessels of each type divided by the product of the strip width and length. 35

72 CHAPTER 9. DOLPHIN CARCASS EXAMINATION AND SAMPLING PROTOCOL INTRODUCTION The examination of dolphin carcasses and collection of biological samples is essential to the science of dolphin conservation. The following protocol provides instruction on dolphin carcass examination and biological sample collection procedures. These procedures should be followed carefully and any deviations thoroughly explained on the back of the Cetacean Carcass Data Form (Annex 1). DATA COLLECTION For all dolphin carcasses or body parts, the mortality monitoring team will record, as possible, the (1) location, date and time; (2) species description and identification; (3) photographs of the carcass; (4) condition of the carcass; (5) evidence of the cause of death according to net, hook or propeller marks, contusions, lacerations, or internal hemorrhaging; (6) standard external measurements and tooth counts; (7) determination of sex and (8) lactating status of females. Location, date and time Response team members will record the exact location from where the carcass was recovered with date and time (GPS position and name of the place). If the location where the carcass is examined is not the same as the one from where it was collected (e.g., a fishermen recovers a carcass at sea and brings it back to his village), information on both of these locations (place names and GPS positions), dates and times of recovery and examination will be recorded. Species identification It is vital to thoroughly document and photograph the diagnostic features of each dolphin carcass. Under no circumstances should response team members guess at species identifications. Diagnostic features including the size and shape of the body, dorsal fin, flukes, flippers and rostrum or beak, and details on the overall coloration (note that carcasses quickly lose their color and become uniformly dark shortly after death) and color patterns (blazes, stripes, cape, contrasts) should be recorded. Drawings should be made regardless of whether the species can be identified or not. The drawings do not need to be artistic. Simple figures showing the diagnostic features are sufficient. Do not hesitate to record the specimen as unidentified if you cannot eliminate other possibilities. Photographs Photographs of recovered carcasses and body parts are essential. Place a measuring tape or scale next to the carcass or body part when taking photographs. Always take a wide angle image first to allow the viewer to place close-up photographs into context. 36

73 Photographs should be taken of the dorsal, ventral, and both lateral sides of the entire carcass. Close-up shots should be taken of distinctive marks, whether or not human caused. Photographs should also be taken of the head, including the mouth and teeth, as well as of any unusual marks, scrapes, scars, wounds, skin lesions or natural external features. Records of all photographs should be made with the initials of the photographer, followed by the image number, and a body part code: D = dorsal side, V = ventral side, LR = lateral right side, LL = lateral left side, H = head, FK = flukes, FP = flippers, M = marks. A photo data base of mortalities will be compiled and each photograph named according to the specimen code and image number that matches the one recorded in the Cetacean Carcass and Body Part Data Form. Carcass Condition The condition of the carcass should be described on the data form. The carcass condition is influenced by factors such as temperature, post-mortem interval and body size. Six condition categories can be used: 1. Animal found alive but subsequently died 2. Carcass in good condition (fresh): little or no bloating skin not sloughed flippers not stiffened vertically internal organs intact 3. Carcass in fair condition (moderately decomposed): slight bloating, due to general tissue decomposition some skin sloughing or stiffening of flippers all internal organs intact 4. Carcass in poor condition (badly decomposed): usually bloated, due to general tissue decomposition missing patches of skin, with flippers stiffened vertically internal organs, particularly the liver, show loss of integrity 5. Mummified carcass (skin holding bones) 6. Disarticulated bones (no soft tissue remaining) Cause of death Conduct an external examination: Note general condition of the animals. Describe and draw scars, lesions, parasites, and fluid discharges. Check carefully for signs of human related injury such as propeller scars, net entanglement marks, missing flippers, deep puncture wounds, and lesions encircling the flippers and flukes. Document marks carefully, including the dimensions of cross-hatching caused by nets, the spacing of cuts or linear scars from propellers, and the size of grooves made by ropes. Look for signs of emaciation and check for the presence of food in the stomach. Question local people or fishermen operating in the area if they have any information about the cause of death or if they observed any unusual behavior exhibited by the animal(s). If 37

74 the carcass was transported from a different location from where it is being examined, find out details on how it was moved to determine if some marks may have been made postmortem (e.g., pulling carcass with help of a rope). When determining the cause of death, it is very important to document both the potential cause and circumstances. For example, a dolphin may have died of suffocation, but was found dead in a gill-net which caused the forced submersion. So the cause of death was drowning, while the circumstance was gill-net entanglement. In some instances signs of human interaction will include evidence from gear or debris removed from the animal. This evidence should be carefully documented, photographed and collected if possible. Standardized protocol and maintaining objectivity is vital when evaluating the cause of death of a dolphin. The most conservative diagnosis is could not be determined. If the animal is thoroughly examined and no evidence of human interactions is found, then the diagnosis is no known interactions. However, if certain factors compromise your ability to evaluate the carcass properly then the finding should be unknown. Measurements of the body and external body parts and tooth counts A series of standardized measurements should be recorded for all carcasses (Figure 11). For consistency, all measurements should be recorded in centimeters (cm). The measurements required are (1) total linear body length, measured from the tip of the lower jaw to the notch between the flukes, (2) height of dorsal fin, (3) beak length, (4) flipper length, (5) fluke width, (6) girth at anterior insertion of dorsal fin or, if the species has no dorsal fin, at the mid-length of the individual, and (7) distance between genital and anal openings. All measurements, except for the girth, should be taken straight along the side of the animal rather than following carcass contours. Figure 11. Illustration of the minimum body measurements to be taken from a dolphin carcass. Measurements are subject to distortion (especially around girth) and are accurate only if taken from fresh carcasses where bloating has not occurred. Measurements, except total body length, do not need be taken on decomposed specimens. 38

75 Tooth counts should be made of the upper and lower right jaws independently. If teeth are missing, record the actual count and note the estimated number of missing teeth in parentheses. Determination of sex The sex of a dolphin carcass can be determined by examining the space between the genital and anal openings and the direction of a pencil (Figure 12). In male dolphins there will be a relatively wide space between the genital and anal openings, and a pencil inserted into the genital opening will be point towards the tail or flukes. In female dolphins there will be a much smaller space between the genital and anal openings, and a pencil inserted into the opening will point towards the head. Mammary gland can be observed in both sexes, but are generally more pronounced in females, especially when they are lactating. Figure 12. Illustration on how to determine the sex of a dolphin. Lactating Status of Females The lactating status of a female dolphin can be determined by making a small incision across the mammary glands. A white milky fluid (sometimes mixed with blood from the cut) will appear if the female is lactating. 39

76 BIOLOGICAL SAMPLE COLLECTION The response team will collect biological samples from each carcass or body part. The highest priority for all species is to obtain a small piece of skin and store it in a numbered vial of preservation fluid (80% ethanol) for genetic analysis. Additional biological samples should be collected as possible. These include (1) blubber for contaminant analysis (stored frozen), muscle tissue for isotope analysis (stored frozen or dried salted), skull for taxonomic analysis and education (stored dry), and teeth for age determination and isotope analysis (stored dry). All samples should be collected with sterilized instruments provided in the dolphin carcass sampling kit. All samples should be tagged with information on the date collected, the initials of the collector(s), and the carcass or body part identification number. Labels should be written with a permanent marker (e.g., pencil or fine point on good quality paper). This information should match the data recorded in the Cetacean Carcass Data Form. For dolphin body parts, use only the applicable boxes in the data form and draw a line through the boxes that do not apply. Collection of skin Three small samples (3cm 3cm) of skin (epidermis, which appears as a thin grey layer) should be collected from the dorsal mid-thoracic area for analyses of genetics, heavy metals and stable isotopes. The samples should also include a small amount of fat (thick white layer underneath) to ensure that the entire skin depth has been sampled. Skin samples should be collected with an unused razor blade. Safely dispose of the razor blade after taking each sample to avoid contamination. Preservation of skin A skin sample for genetics should be placed in a plastic vial with 80% ethanol, as provided in the dolphin carcass sampling kit, or preserved frozen or dried. Place the vial or sample in a zip-lock bag and label the bag (see below) before storing it in a cool place. If the skin sample is collected dried, place it in a freezer as soon as possible after collection. The two other samples should be saved for heavy metal and stable isotope analysis. These samples should be placed in plastic vials but without ethanol and should be preserved either frozen or dried. Labeling It is very important to record the vial number, date of collection, name of the species (First letter of the genus and first three letters of the species), carcass number and the descriptive name of the sample/body part. Be sure to always clearly indicate which samples have been collected for genetics and stored in ethanol and which have been collected for heavy metal and isotope analysis. 40

77 Blubber Blubber samples are collected for studies of contaminants. To collect blubber samples, make an incision into the skin and through the blubber in the dorsal mid-thoracic area of the animal. Extract two 3cm 3cm pieces by lifting one corner and separating the skin and blubber layers from the underlying red muscle tissue. Wrap the blubber samples in aluminum foil (shiny side of the foil facing out), place them in a zip-lock bag and label the bag as instructed above. Store the samples in the freezer as soon as possible after collection. Mark the box of blubber in the Cetacean Carcass Data Form. Muscle Muscle samples are collected for studies of stable isotopes, which provide information about diet and habitat of animals, and heavy metal contamination. To collect a muscle sample, make a deep incision through the skin and the blubber in the dorsal mid-thoracic area of the animal. Extract a 3cm 3cm cube from the underlying red muscle tissue. For both stable isotopes and heavy metals place the sample in a zip-lock bag and label the bag as instructed above. Store the sample in the freezer immediately after collection. Alternatively the samples can be placed in a handful of salt and stored in a zip-lock bag. Mark the box of muscle in the Cetacean Carcass Data Form. Liver Liver samples are collected for studies of heavy metals. To collect a sample, cut a 3cm 3cm cube from the liver. Place the liver sample in a zip-lock plastic bag and label the bag as instructed above. Store the sample in a freezer immediately after collection. Mark the box of liver in the Cetacean Carcass Data Form. Stomach Tie off the oesophagus where it enters the stomach and cut above the tie. Tie the small intestine twice where it leaves the stomach and cut between the ties. Remove the stomach by cutting through its attachments, and place it in a sturdy bag. Keep the spleen and pancreas in a separate bag. Label the bags as instructed above (e.g., 2010-Dec-04-PGAN1- Stomach) and store the samples in the freezer. Mark the box of stomach in the Cetacean Carcass Data Form (Annex 1). Skull Collecting the skull is important for taking detailed measurements used to better understand the taxonomy of the species and for educational purposes. To obtain the skull either separate the whole head from the carcass and clean it of soft tissue, or bury the carcass and extract the skull after the soft tissue has completely decomposed. 41

78 Teeth Teeth are collected for the age determination. Extracting teeth from the jaws of dead animals can be done in the field with a knife or pliers. When animals are decomposed and only limited sampling is possible, it may be simplest to remove all or part of the jaw if time does not permit the removal of individual teeth. Remove five to ten teeth and place them in a zip lock bag. Label the bag with the collection date, name of the species (first letter of the genus and first three letters of the species), carcass number and sample name. Store the samples in a dry place. Mark the box of teeth in the Cetacean Carcass Data Form. CETACEAN CARCASS SAMPLING KITS Cetacean carcass sampling kits will be provided to all stranding response team members. These kits include: (1) 10 pairs of plastic gloves, (2) measuring tape, (3) 10 razor blades, (4) 10 coded vials for skin sample preservation, (5) 10 large zip-lock bags, (6) one pair of pliers for tooth extractions, (7) one polyethylene tarp for wrapping carcass, (8) 10 pieces of aluminum foil for wrapping blubber and liver samples, (9) pencils, erasers, sharpeners, and a marking pen, (10) cotton string for tying off stomach, (11) disinfectant, (12) a sharp knife for opening carcass/extracting organs, (13) one cool box for storing and transporting specimens,(14) teflon tape for sealing plastic containers with skin samples, (15) one pair forceps, and a clipboard with copies of the Cetacean Carcass Data Collection Form. 42

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80 INTERNATIONAL UNION FOR CONSERVATION OF NATURE IUCN Asia Regional Office 63 Soi Prompong Sukhumvit 39 Wattana , Bangkok, Thailand Tel: