Pinnipeds Andrew W Trites Marine Mammal Research Unit Fisheries Centre, UBC
Pinniped Outline 1. Species in Canada & Pinniped Families 2. Life Cycles Arrival on land or ice Delivery, lactation, attendance, weaning Mating Moulting Migration / dispersal 3. Case Histories harbour seals & Steller sea lions 4. Family Comparisons phocids vs otarids vs odobenids
3 Families 33 species Phocids (18) Southern phocids (monachinae) - 8 Northern phocids (phocinae) - 10 Otarids (14) Sea lions (Otariinae) - 5 Fur seals (Arctocephalinae) - 9 Odobenids (1)
12 Species in Canada Breeders Atlantic walrus Ribbon seal, ringed seal, bearded seal Hooded seal, harp seal Grey seal, harbour seal Steller sea lion Migrants Northern elephant seal California sea lion Northern fur seal
Life Cycle DEC NOV OCT SEP JAN FEB MAR APR Fattening and lactation Moulting AUG JUL JUN MAY Mating Pupping
Life Cycle Arrival on land or ice Delivery Suckling / lactation Attendance Weaning Mating Moulting Migration / dispersal
Arrival on land or ice Male before female Stimulates birth
Delivery Single pup precocious Cephalic / breech Umbilical cord / placenta Most females vocalize Pups many species cease vocalizing after weaning
Suckling Pups nurse within hours of birth On land / ice (except walrus) Bouts ~ 11 min phocids every 3.4 h ~17 min otarids every 2.7 h Teats Otarids & Odobenids 4 Phocids 2 (except monk & bearded 4)
Lactation Lactation 4 d to 4 years Phocids brief (4 d several weeks); rich milk; rapid pup growth Otarids long (several months - > 2 years); slow growth Odobenids 2+ years; slow pup growth
Attendance Relocation (odour, sound) Phocids Females tend to not leave their pups Pups solitary Pups fatten rapidly Otarids Pups sedentary until female leaves of first feeding trip Pups gather in pods / interact with other pups Males more active than females
Weaning Phocids: abrupt Post weaning fast 1.5 12 weeks Otarids: gradual
Mating / copulations Phocids: at end of weaning Otarids: ~1 week after birth Usually on land Fertilized egg Blastocyst: hollow ball of cells Dormant 3.5 4 months Moves to 1 of 2 uterine horns Implants in wall of uterus Cue for implantation: photoperiod?
Moult Adults Phocids short period on land Otarids shed continuously over 1-2 months Pups Before weaning In utero (harbour seal)
Why do pinnipeds haul out? Breeding season Place to have pup Thermo-regulation: pups Predator avoidance Mate selection Other times of year Resting / sleeping Thermo-regulation Moulting: skin cell maintenance Predator avoidance
Arrival on land or ice Delivery Suckling / lactation Attendance Weaning Mating Moulting Migration / dispersal Life Cycle Moulting OCT NOV SEP AUG Mating DEC JUL Fattening & lactation JAN JUN FEB MAR MAY APR Pupping
Pinniped Life Histories Steller sea lions & harbour seals
BC Abundance 1913-1964 bounty (200,000 240,000 killed) 1962-1968 hunted for pelts 1970 ~10,000 1977 ~85,000 1995 ~130,000 2007 ~140,000
Haulouts # hauled out correlates with tide, air temperature, winds & precipitation 35-60% of total population haul out Mid-day peak or early afternoon common
Easily disturbed Haulouts Under what conditions do haulouts form? Abundance estimates need to correct for proportion at sea Spend 2/3 of time in water
Colonization Pacific colonized twice 670,000 years ago 380,000 years ago
5-6 weeks (Pacific) Lactation 3-4 weeks (Atlantic)
Mating Females come into estrus around the time of weaning Males make visual & auditory displays in the water Males are vigilant
Moult Numbers hauled out increase in the fall while seals moult
Steller Sea Lions
Steller Sea Lion Rookeries
Rookery bulls pups females
Haulout (mixed) Bulls Yearlings Females
Rookery Season: May Aug Births: June
Bulls 40 days 2 years First to arrive Fight for territories
Body Size Bulls: 3.0 m Females: 2.3 m Pups: 0.5 m Bulls: 750 kg Females: 300 kg Pups: 20 kg
Birth Single pup Milk Perinatal period 7 days
Mating 1 week after birth 8.5 month gestation Delayed implantation
Foraging Trips Summer: ½ 2 days Winter: 1-4 days herring, sandlance, salmon, cod, rockfish, octopus, squid, pollock, Atka mackerel
Foraging Trips Prefer coastal shelf within 45 km of shore Can be found >100 km & >2000 m deep Shallow, short dives (3 min aerobic)
Reuniting Vocal & olfactory cues Accept only their pups
Pups Can walk and swim soon after birth Enter water when 4-6 weeks olds
Nursing Some 1 year Some 2 years A few 3 years
Vital Statistics Sexual maturity females 3-4 y males 7-8 y Survival females > males females : males 3:1 by age 10 y
Predators Killer whales Sharks? humans
Other Sources of Mortality? Disease Starvation
Steller Sea Lion Rookeries Western Stock Eastern Stock
Family Characteristics In some ways the families are similar mammals Adapted to aquatic existence Give birth on land or ice (unable to give birth in water) In other ways the families differ Morphology Behaviour Abundance Distribution
Ears Morphology Otarids ear flaps (others none) Teats Otarids & Odobenids 4 Phocids 2 (except monk & bearded 4) Skeleton Otarids enlarged thoracic & cervical vertebrae to support muscles for walking & swimming Phocids enlarged lumbar vertebrae for swimming
Flippers Morphology (cont.) Otarids hairless drawn under Phocids hair covered drag Sexual dimorphism All otarids & odobenids; some phocids Swimming propulsion Otarids front Phocids & Odobenids hind
Behaviour Breeding systems Phocids variable Otarids all polygynous Odobenids polygynous (mobile lekking)
Behaviour Timing of mating Phocids variable (during lactation or after weaning) Otarids few days after birth Odobenids during lactation
Behaviour Lactation Phocids brief (4 d several weeks) Otarids long (several months - > 2 years) Odobenids 2+ years
Behaviour Moult Phocids short period on land Otarids shed continuously over 1-2 months
Abundance 33 species 70 million 90% phocids 10% otarids & odobenids Decreasing order of abundance Crabeater,ringed seal, harp seal, northern fur seals
Distribution Phocids inhabit widest range of habitats Fresh waster lakes, river,s estuaries, ocean But not in tropics (except monk seals) Otarids only inhabit the marine environment But not extreme polar regions Don t use ice Most fur seals in southern hemisphere
Distribution No pinnipeds in some parts of the world Asia & India Fewer species inhabit the Antarctic than Arctic, but numbers much higher in Antarctic
Pinniped Outline 1. Species in Canada & Pinniped Families 2. Life Cycles Arrival on land or ice Delivery, lactation, attendance, weaning Mating Moulting Migration / dispersal 3. Case Histories harbour seals & Steller sea lions 4. Family Comparisons phocids vs otarids vs odobenids