PLEASE LIMIT RESPONSES TO SPACE PROVIDED. USE REVERSE SIDE OF PAGE IF ABSOLUTELY NECESSARY. RESPOND TO ALL QUESTIONS ON THE EXAM FORM.

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1 FISH 475: MARINE MAMMALOGY. SPRING 2008 FINAL EXAMINATION. NAME: KEY PLEASE LIMIT RESPONSES TO SPACE PROVIDED. USE REVERSE SIDE OF PAGE IF ABSOLUTELY NECESSARY. RESPOND TO ALL QUESTIONS ON THE EXAM FORM. 20 pts. per question except as noted. Total of 360 pts. possible. 1 (4 pts each part). Indicate the technical family name for eeach of the following species of marine mammals: Graded by Glenn VanBlaricom: Baird s Beaked Whale: West Indian Manatee: Polar Bear: Sea otter: California Sea Lion: Ziphiidae Trichechidae Ursidae Mustelidae Otariidae 2 (10 points each part). Describe one anatomical feature and one behavioral attribute that may reduce risks of decompression sickness (defined as circulatory impairments caused by formation of nitrogen bubbles in the blood stream during dives) in diving marine mammals. Graded by Glenn VanBlaricom: Anatomical features (full credit for either): a) Collapsible alveoli in lungs: High flexibility of rib cage and thoracic tissues allows lungs to collapse fully during dives by most marine mammals. The process includes full collapse of alveolar sacs in lungs, forcing respiratory gasses into adjacent reinforced airways that are poorly vascularized, and from which little nitrogen can diffuse across membranes and into the blood. b) Storage of oxygen in tissues other than the lungs: Because nitrogen management includes a requirement to reduce access of gasses in lungs to the blood supply, oxygen in the lungs must be stored elsewhere during dives so it can be utilized during the dives. Marine mammals have enhanced capacity for storage of respiratory oxygen in blood and muscle. This feature allows marine mammals to survive with small lungs proportionate to body size, further improving the efficiency of nitrogen management.

2 a) Slow ascent rates at the end of dives; b) Exhalation of gasses from the lungs prior to a dive; c) Inclusion of decompression stops as part of the ascent profile at the end of a dive. 3 (10 points each part). Recall the logistic (density-dependent) equation for population growth: N t+1 = N t + N t r(1 [N t /K] z ) Where N t = population size at time t; t = time in years; K = Carrying capacity of the population; z = shape parameter Define Optimum Sustainable Population (OSP) using terms from the logistic equation. How does the range of values represented by OSP change with changes in the shape parameter (z)? Graded by Teresa Mongillo: OSP is the range of population sizes between the Maximum Net Productivity Level (MNPL) of the population and K. MNPL is the population size at which the slope of a plot of population size (N t ) over time (t) is at its maximum value. Since the slope of a continuous function of population size over time is dn/dt, OSP is, therefore, the range of population sizes between K and the maximum value for dn/dt. In general, as z increases, the value of MNPL also increases. As a result, the lower bound for the OSP range gets larger while the upper bound (K) remains unchanged. Thus, the OSP range becomes smaller as z increases. 4. Pups of true seals may have low odds survival if they do not establish acoustic and olfactory cues for recognition of their mother at birth. However, true seals typically remain on breeding grounds with their pups until the pups are weaned. Why, then, are the olfactory and acoustic recognition cues necessary? Graded by Teresa Mongillo: Pups and mothers may become separated on the hauling grounds even if the mother remains hauled out for the entire period from birth to weaning. The most likely causes of separation of pups and mothers are large ocean waves sweeping over haul-outs as a result of storms, and disruptive activities on the hauling grounds caused by fighting and territorial defense among males. If pups do not find their mothers soon after separation, they are at risk of starvation or injuries caused by unfamiliar animals. Olfactory and acoustic identification cues are effective in allowing pups and mothers to become reunited following separation.

3 5 (10 points each part). Most sea otter pups are born in late winter or spring and weaned during late summer or fall. However, in every sea otter population there are pups born and weaned at other times of the year as well. By what mechanism do these out-of-season births occur in sea otters? What might be an advantage of an out-of-season birth to a sea otter pup s mother? Graded by Glenn VanBlaricom: Generally the optimal time of year for pupping by sea otters is spring, because this normally is the time of maximum productivity in prey species. As a result, a lactating female has access to the most productive prey resources at the time when her metabolic demands are the highest. Spring also is normally the end of the stormy season, reducing the risk that a small dependent sea otter pup will become separated from the mother as a result of bad weather or rough seas. However, if a nursing pup is lost, an adult female sea otter can go into estrous (i.e., become behaviorally and physiologically receptive to mating) soon after and become pregnant again, even if it is not in the normal time of the year. An out-of-season birth allows a female sea otter to recover some of the reproductive fitness she lost with her previous pup. In most cases females that have out-of-season births eventually return to the normal reproductive pattern after a few years. Retuning of the reproductive cycle over time, by virtue of variation in period of delayed implantation of embryos in pregnant females, may help an adult female return to the normal breeding cycle. 6. You are conducting a line transect survey to estimate abundance of fin whales in the Gulf of Alaska, over a pre-determined ten-day period. The survey platform is a large, very expensive NOAA research vessel that has a tight schedule of other obligations following completion of your survey. During the first half of the survey weather conditions are excellent, but on day six skies become heavily overcast and a steady light rain begins to fall. The weather forecast indicates continuation of gray skies and rain for the remainder of the survey period. Do you continue the survey when the weather changes, or do you terminate the survey early? Explain your decision. How will your decision influence your goal of estimating fin whale density in the study area? Graded by Glenn VanBlaricom: The options are to continue the survey despite the weather change, or to terminate the survey at day 6. Either option can reasonably be exercised depending on circumstances. If the change in weather produces conditions in which visibility is so poor that the probability of sighting whales on the track line is significantly less than 1.0, then there is no choice but to terminate the survey, because data collected under such circumstances violate key protocols of line transect theory. If the survey must be stopped, the data collected up to the time of the weather change are still usable. However, the resulting density estimate can be applied only to those portions of the study area that have been surveyed. Thus, the value of the survey in estimating the number of fin whales in the Gulf of Alaska will be limited. If the change in weather does not eliminate the ability to see whales, and allows sighting probability on the track line to remain at 1.0, then the survey can continue.

4 Although the sighting probability curve over distance from the track line will change, line transect theory will allow computation of a new effective strip width that accommodates the change in detection probabilities. Thus, the density estimate for the second part of the survey is not affected by the weather as long as all line transect protocols are observed. When computing a density estimate from the data, you would be well-advised to compute estimates for the two parts of the survey separately, and to apply each density estimate only to the respective portions of the study area in which each part of the data was collected. 7 (10 points each part). The Southern Resident killer whales (SRKW) have recently been listed as endangered under the federal Endangered Species Act, and the National Marine Fisheries Service is proceeding with recovery planning for this population by considering the potential impacts of several key risk factors. Prominent risk factors include a reduction in prey quality and/or quantity, impacts from high toxin loads, direct and/or indirect vessel impacts, and random fluctuations in a small population dealing with the cumulative effects of combined risk factors. Based on your knowledge of SRKW and their distribution patterns within Washington and British Columbia inshore waters, describe (a) which risk factor you think is most important for NMFS to study first in this region and why you think so, and (b) a research approach to study the risk factor you identified in (a). Graded by Teresa Mongillo: (a) (10 pts) Which risk factor is identified and why is largely up to student choice (1 pt each). However, the student must answer both parts, providing clear and reasonable justification for choice of risk factor. (b) (10 pts) There are several reasonable approaches, and it will depend on which risk factor chosen in (a). Here are some examples, but other reasonable approaches also will be considered: Prey quantity and quality: 1. Statistical model comparing population trajectory of SRKW with prey population trajectory 2. Analyze SRKW space use patterns in relation to prey distribution during periods of SRKW population growth versus population decline. 3. Analyze animal health from periods of population growth versus decline (e.g. use fatty acids to look at changes in diet, lipid composition, etc.) Toxins 1. Measure toxin levels of various levels of the food chain and SRKW, compare relative levels, and model transfer pathways 2. Map distribution and levels of toxins throughout Puget Sound Vessel impacts 1. Acoustics: Measure noise levels of various vessels, at a range of distances from the source. Consider impacts, based on known levels of killer whale hearing thresholds. Model potential of masking killer whale calls.

5 2. Bioenergetics: Monitor behavioral changes in the presence of vessels, and model bioenergetic impacts of changes in behavior or diving patterns Random population fluctuations 1. Population modeling exercise: Construct age-structured model that allows testing of multiple scenarios to explain population fluctuations, including random walk model. 8 (10 points each part). In this year s class line transect sampling exercise (the one about the rat chow pellets on the FSH front lawn), population density point estimates for some of the survey teams in the Monday lab were higher than the actual density. How is this possible? How might the survey protocol have been modified in order to minimize this apparent bias? Graded by Cris Elfes: It is possible that the pellets were not distributed at random with respect to distances from the track lines used in the survey. If the pellets were, on average, closer to track lines than would be expected from a random distribution of pellets in the survey area, then the overestimation problem would result. If in fact pellet distribution was biased toward closer-than-random distributions relative to the established track lines, the addition of more track lines should have provided a data set with reduced overall bias. Other reasonable responses will also be considered. 9 (10 points each part). Most fur seal species forage on the organisms that comprise the deep scattering layer. Foraging dives are frequently deeper during the day than at night. Why? Fur seal diving profiles often indicate that foraging ceases for a period of 1-2 hours right around midnight. Suggest two possible explanations for this commonly-observed break in foraging activity. Graded by Cris Elfes: Foraging dives are deeper during the day than at night because the primary prey of most fur seal species are organisms of the deep scattering layer (DSL) assemblage, which collectively migrates to deep water during daylight hours, and moves closer to the surface at night in order to forage on preferred prey in shallow water under cover of darkness. The cessation of foraging near midnight, frequently observed in the diving activity profiles of fur seals at sea, may result from one or both of these factors (full credit for any two): a) Because fur seals do not echolocate, they may be unable to detect DSL prey organisms visually under conditions of complete darkness that often prevail near midnight. b) Fur seals may become satiated with prey as access to the vertically migrating DSL becomes progressively easier (i.e., requiring shallower dives) during the evening hours prior to midnight.

6 c) Fur seal foraging activity near midnight may be so close to the surface that time-depth recording devices attached to the fur seals may not recognize or record foraging activities as dives. Other reasonable explanations will also be considered. 10 (10 points each part). The western North Pacific gray whale (WGW) population numbers about 130 animals, while the eastern North Pacific gray whale (EGW) population numbers over 20,000 individuals. Both populations were subject to whaling mortality in previous centuries. Indicate two likely explanations (other than whaling history) for the large difference presently observed in population sizes between WGWs and EGWs. Graded by Teresa Mongillo: Possible explanations include the following (full credit for any two): a) WGWs may have been hunted to a small-enough population size that depensation came into effect, severely limiting growth of the population once whaling ended. EGWs may not have been hunted down to a population size below a depensation threshold, with the result that the population grew much more rapidly once whaling ended. b) WGWs may be exposed to greater effects of contaminants or other anthropogenic disturbances, as compared to EGWs, either on their summer feeding grounds or winter breeding grounds. c) The relatively frequent incidental capture and drowning of WGWs in fishing nets during migration, especially in waters near Japan, may be adding to other causes of depensation and keeping WGW numbers and population growth rate at low levels. Bycatch may be a lesser problem for EGWs, especially if EGWs were never reduced to numbers below a depensation threshold. Other reasonable explanations will also be considered. 11. In a Leslie Matrix type population model, what happens to the age distribution of animals (i.e., the proportional distribution of animals in different age classes relative to the total population) as the model is sequential applied to the population over a large number of time steps? Graded by Teresa Mongillo: Eventually the age distribution becomes stable i.e., it does not change from one time step (usually each time step is one year) to the next.

7 12 (10 points each part). Describe two major biases associated with use of scat (fecal) analyses to determine the diets of pinnipeds. Graded by Cris Elfes: Possible biases include the following (full credit for any two): a) Scat analyses depend on recovering of hard part remnants (bones, scales, or eye lenses from fish, and beaks from cephalopods) from scats. However, the probability of retention of prey hard parts in scats varies with prey species, as a result of differences in size or resistance to digestion during passage through the gut of the consumer species; b) Prey remains found in scats likely represent only the prey most recently consumed, the prey consumed closest to the haul-outs from which scats were recovered, or both. For consumer species that range far from haulouts or remain at sea for long periods, prey data determined from scat analyses may, therefore, represent a strong bias against the true diet of the consumer; c) Scats collected on a haulout are not necessarily representative of all pinnipeds in the population, or even all pinnipeds that use a particular haulout. Some animals almost certainly leave more scats on haulouts than others, for a variety of reasons, thus creating a bias in the data against individuals tha defecate less frequently on the haul-outs. Other reasonable suggested biases will also be considered. 13. (10 points each part). Define depensation (also known as the Allee effect ). Describe a biological mechanism by which depensation might influence population dynamics in a whale population. Graded by Cris Elfes: Depensation is a reduction in the per capita production rate (i.e., the average rate at which adult females produce offspring per unit of time), as compared to modeled expectation, in a population of organisms when the population is small relative to its known maximum size or carry capacity. Possible mechanisms include the following (full credit for any one): a) Difficulty in locating receptive individuals of the opposite sex with which to mate; b) Genetically-based reduction in fitness resulting from inbreeding; c) Intensive predation on juveniles by other species. Other reasonable suggested mechanisms will also be considered.

8 14. Walruses feed primarily on large infaunal clams that must be excavated from bottom sediments prior to consumption. Suggest the mechanism by which walruses likely determine where to dig for prey. Graded by Cris Elfes: Walruses probably locate prey organisms in benthic marine sediments by probing the sediments with the vibrissae. The vibrissae are highly enervated, very sensitive to touch and movement, and can be moved and directed individually. Walruses push the muzzle into sediments on the sea floor, probing with the vibrissae until prey items are detected. Once a prey item is detected and excavation of sediments begins, walruses may begin digging a furrow or trench to continuously expose infaunal prey, using the vibrissae to locate the prey on the leading edge of the furrow as they move forward. 15. Sperm whales often consume large numbers of very small fishes, such as myctophids, as prey. Given the external anatomy of sperm whales, suggest an explanation (other than the acoustic stunning hypothesis) for the ability of sperm whales to consume so many small prey items. Graded by Cris Elfes: Most odontocetes are able to produce strong suction into their mouths by retracting their tongues backward into their throats. This is made possible by a pair of retractor muscles in the back of the throat that are quite strong and capable of rapid contraction. It is possible that sperm whales use the suction associated with rapid tongue retraction to capture small prey. We know little about responses of myctophids and other common DSL fishes to approaching predators especially those the size of a school bus with noses as big as a Hummer. However, if escape response abilities of the fish are limited, then oral suction may be the primary method for capture by foraging sperm whales. 16. You find the decomposing carcass of a large cetacean on an ocean beach on the outer coast of Washington, near La Push. Although the carcass is a real stinker, most of the major external anatomical features are still apparent. Baleen is present in the animal s mouth. How would you determine the family of cetacean to which the carcass belongs? Graded by Glenn VanBlaricom: Pygmy right whales (family Neobalaenidae) can be eliminated because they have been observed only in the southern hemisphere and are considered rare. The remaining three possibilities are the rorquals (Balaenopteridae), the gray whales (Eschrichtiidae), and the right whales (Balaenidae). Of these the rorquals or gray whales are the most likely, but right whales cannot be entirely discounted despite their relative rarity. If the animal is on its side or back, patterns in the throat pleats can be used to determine the family. Right whales have no throat pleats, gray whales have only a few short ones, and rorquals have many pleats of great length as compared to overall body length. Baleen plates can be used for identification to family if the throat region is not visible. Right whales have long baleen plates (up to several meters) with extremely fine loose

9 fibers on the inner edges. Baleen plates of gray whales and rorquals tend to be much shorter, and typically are much stiffer with much coarser fibers, as compared to right whales. Gray whale baleen is usually very light in color, while rorqual baleen is dark brownish to black. In addition, there are a few other cues that can be helpful. Gray whales typically have much heavier loads of ectoparasites on the skin as compared to rorquals and right whales. In addition, the ectoparasite load on the heads of gray whales typically is much heavier on the left side as compared to the right. Finally, the size of the head in right whales is typically very large proportionate to total body length (about 1/3), much more so than in rorquals or gray whales (about 1/5 to 1/10 in the latter two families. 17. Explain why caution must be observed in characterizing the foraging habits and behaviors of a marine mammal species based only on interpretation of the species anatomical features. Graded by Glenn VanBlaricom: Apparent functions of various body parts in marine mammals may not always reflect reality, for several reasons, including the following (full credit for any one): a) The range of functions provided by a body part during foraging may only be apparent after directly observing the behavior of the animal while it is foraging. A good example is the use of tail flukes by killer whales to disable herring while foraging in Norwegian fjords. A second good example is the walrus, which, contrary to reasonable expectation, does not use the tusks for foraging. Instead, walruses use a combination of searching with vibrissae and digging with oral water jets, pushing action by the muzzle, and fanning with flippers to expose and capture infaunal prey from sediments on the sea floor. b) Some body parts are functional only in social contexts and do not function in foraging, despite appearances. Walrus tusks may be the best example. There are other cases that appear to serve as examples at first glance, such as the narwhal tusk or the teeth of beaked whales. However, many of these can be eliminated as potential foraging devices based on simple anatomical comparisons between males and females. If a feature is present only in one sex, it is probable (although not 100% certain) that the feature does not have a functional role in foraging (note that walrus tusks occur in both sexes and function socially for both sexes, although typically the tusks are larger in males). c) It is always possible that a given body part in an organism is simply an evolutionary anachronism that has not (yet) been genetically selected for removal. Vestigial leg bones in whales are an example, although they are of course not implicated in foraging. There are no obvious examples of such anachronisms in the context of foraging in marine mammals, but there may be

10 subtle anatomical features that might appear to be functional in foraging, but in fact are not. 18 (10 points each part). The marine ecosystems near the Galapagos Islands are highly productive and support large populations of prominent consumer species such as marine iguanas, fishes, sea birds, pinnipeds, and cetaceans. However, the Islands are located on the equator, and the associated marine environment is exposed to intensive surface heating from incoming solar energy year-round. Why is this pattern paradoxical? What mechanism(s) facilitate(s) the high productivity of the marine ecosystems near the Islands? Graded by Teresa Mongillo: The pattern is paradoxical because intensive solar heating normally is associated with stratification of the oceanic water column. When a water column has strong thermal stratification, a large amount of mixing energy typically is required to replenish inorganic nutrients, required by phytoplankton near the surface to drive high rates of biological productivity across food webs. Such mixing energy is normally not available at low latitudes. High biological productivity in the Galapagos region is facilitated by upwelling of deep, cold, nutrient-rich waters from two sources. Local upwelling occurs as a result of equatorial divergence driven by prevailing trade winds on each side of the equator. In addition, the Galapagos region may benefit from a subsidy of cold, nutrient rich, upwelled water from the northern end of the Humboldt Current system, which trends northwesterly off the coast of Ecuador and drifts towards the Galapagos region.