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Cetaceans (order Cetacea) Whales, Dolphins and Porpoises Two kinds of whales and dolphins Mysticetes= Baleen whales Odontocetes= Toothed whales, porpoises.

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Presentation on theme: "Cetaceans (order Cetacea) Whales, Dolphins and Porpoises Two kinds of whales and dolphins Mysticetes= Baleen whales Odontocetes= Toothed whales, porpoises."— Presentation transcript:

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3 Cetaceans (order Cetacea) Whales, Dolphins and Porpoises Two kinds of whales and dolphins Mysticetes= Baleen whales Odontocetes= Toothed whales, porpoises and dolphins

4 Killer whales (Orcinus orca) Distributed world-wide Live in matriarchal groups called pods Off-shore and inshore pods have different pod structures Specialize in their feeding habits & hunt in groups Life expectancy of 30 and >50y for males and females Sexual dimorphism – males larger, up to 10m w/ 2m dorsal fin Gestation 17mo, then nursing for 18mo, high infant mortality Sexual maturity at w/ adolescent period Menopause in females at ~40y

5 Distribution of Killer Whales in N Pacific Krahn, M.M., et al Status review of Southern Resident killer whales (Orcinus orca) under the Endangered Species Act. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-54, 133 p. (available off the class web) Offshores & Transients

6 N. Pacific Orca Dynamics Communities, superpods, pods, subpods found all along coast from PS to Arctic Average size is ~150 individuals for a community Best guess of Killer whales in Eastern N Pacific Communities in Price William Sound and our Southern Residents well studied Northern residents less well studied Echolocation clicks are repeated (pulsed) sounds in the 1 to 10 Khz range

7 Salish Sea Orca History No wide-spread hunting by native Americans Tribal stories for orca creation propose them to be human (in many instances) ‘hunted’ by military along with seals and sea lions in PS, Aquarium trade capture

8 4 Sympatric Communities Offshores Transients Northern Residents Southern Residents

9 Differences in dorsal fins

10 Killer Whale Discrete Calls Discrete dialects (acoustic clans) that are semi- stable through time SR’s have 1 clan, NR 3 and SAR 2 Time Frequency (Hz)

11 Ecolocate, sing & whistle echolocation singing whistle

12 Lets look at each group

13 Transients Communities Found all along Americas, Arctic to Antarctic More abundant in colder water Feed on other marine mammals Pod structure is small and inclusive of members of either sex ‘lone bulls’ live outside of pod structure Morphological differences Fin shape, animal size Acoustic differences Actively avoid the fish-eaters Unpublished genetic data suggests divergence >10,000ybp, unique ‘species’ In individuals in <10 pods ID’d from ~175 known individuals Attempt to watch Video

14 Recent Transient Hunting A pod of transients were in Hood Canal for 2 mo last winter (Jan-Feb 2003) Take of ~600 seals, roughly half the population T14, one of the whales in the transient pod, was captured in Hood Canal in the early 1970’s for the aquarium trade, then subsequently released after a public outburst against the captures. If retained, he would have been the only transient ever studied in an enclosed aquarium

15 Hunting video This video taken off the Ca coast in 1998, similar feeding strategy used by transients when they were in PS

16 Offshore Community Only ‘discovered’ in early 1980’s Least information for these individuals since they rarely come in shore Appear to live further offshore than the continental shelf (>70km) 200+ individuals Observed as far south as S. California Genetically similar to southern residents in their maternal lineage (mtDNA), and fin structure is similar too, but these two groups have never been observed together Thought to be fish-eaters

17 Offshore encounter A group of offshores was observed on May 1st, 2003 in Haro Strait

18 Northern Community 200+ individuals (up from ~110 in 1965) 8.5% population decline since 1997 Gulf Islands to Queen Charlotte Island Most similar echolocation, acoustics, pod structure, etc. to southern residents, but not known to regularly interact with southern residents

19 The Southern Residents 3 (4) pods in the community J,K and L Pods (L-10 subpod) Salmon (90%) of diet Known to take mammals and other fish on occasion J-pod year-round in Salish Sea Usually winter in PS, rarely observed outside of Salish Sea K and L pods go offshore Dec-May Observed both N and S Return within a week of each other usually Reunion of three pods includes ‘singing’ and rubbing Return precedes local salmon runs by 1-2 weeks

20 Southern Residents Use top and bottom of water column Dives are deep and direct Calving interval ~5yrs (0-12) 1950’s population ~125 individuals …despite random target practice & bad reputation …aquarium trade took ~45 individuals from the population between

21 Pod Structure of residents and off-shores Matrilines  brothers and sisters swim together Breeding occurs cross-matrilines If one pod is male-poor, the other pods could potentially suffer If one pod loses its females, that pod will go extinct

22 Summer distribution of southern residents Genetic studies: Hoelzel et al. 1991, 1998, Barrett-Lennard 2000   Discrete population that is genetically distinct from the northern resident population in B.C.

23 SR usage of Haro Straits region J pooledK pod L pod Data analysis by Donna Hauser, data from the international sighting network

24 J Pod Movement Sequences (Summer 2001) Committed Turn around Back/Forth 50/50 Data analysis by Erin Heydenreich, data from the international sighting network Clockwise movement common

25 Molecular studies Mitochondrial DNA analyses (not shown) link maternal lineage of offshores to the residents Microsatellite data (shown at right) separates residents from other KWs

26 More N&SR’s Most well known whales in the world SRs did not adopt Springer in 2002 Luna still in Nootka Sound “Fearing that a lonely killer whale could injure or kill someone, a team of Canadian authorities and scientists is debating the whale's fate, while police are cracking down on people who pet the creature. The three-and-a-half year-old orca, nick-named Luna, is "pathologically social," says marine biologist Lance Barrett-Lennard of the Vancouver Aquarium in this west coast Canadian city.” NR’s creating new pods, SR’s might be One expatriate, Lolita, still alive and living in Florida

27 Lolita Last living capture from the Southern Residents Currently at Sea World, Florida

28 Current SR population tally Is the population rebounding from its most recent decline?

29 Current pressures Food availability & carrying capacity Pollution Noise Organic contaminants Popularity Population size and the Allee effect Complicated by pod structure and breeding profiles Let’s focus on this last theme

30 Excerpted and updated from: Dynamics of small populations A presentation provided by: Paul R. Wade National Marine Mammal Laboratory Alaska Fisheries Science Center NOAA Fisheries Seattle, WA

31 The dynamics of small populations become different from large populations Small populations are at risk of extinction Naturally rare populations exist that appear stable (e.g., vaquita, Carrribean monk seal) Populations driven to low numbers by human- caused factors harvest bycatch habitat degradation

32 Small Populations are the focus of ecological study because of conservation and endangered species issues Stochastic demographic and genetic factors determine the minimum size of a viable population 3 demographic factors demographic stochasticity environmental stochasticity catastrophes

33 Populations driven to low numbers face a risk of extinction just from being a small population Depensation/Allee effects critical density below which the population is likely to go extinct (in a probabilistic sense) Stochastic population dynamics Demographic and environmental variance can cause a small population to go extinct just from chance alone

34 Causes of Allee effects Genetic inbreeding and loss of heterozygosity inbreeding depression -- expression of deleterious recessive alleles loss of diversity through drift -- drift occurs much more rapidly in small populations Behavioral/demographic causes such as a reduction in cooperative interactions Shortage of fertilization or mating opportunities anti-predator strategies become inefficient in small groups of prey

35 Allee effect from mating strategy Whales generally remain in the pod they are born in for life (or at least 27 years) Males mate outside of pod Lack of males in other pods could lead to reduced fecundity in a pod if mating strategy is followed strictly

36 Allee effect

37 Allee effects Difficult to study small sample sizes need population growth at different population levels to detect (“contrast”) historical/retrospective analysis important but difficult to interpret Meta-analysis found evidence of Depensation in some fish stocks

38 PVA estimates for the extinction of SR Full record, no catastrophes Full record, 2% catastrophe record, no catastrophes record, 2% catastrophe

39 PVA estimates for the extinction of SR NOAA NMML PVA runs suggest that a single tragedy of major proportions (Exxon Valdez) could wipe out the SR population

40 What about variability in survival or birth rates? Both survival (shown at right for old males) and fecundity (bottom right) show periodicity over the last 30 years

41 Environmental variance in survival

42 Hard to predict fate of a particular population 2 populations of pinnipeds harvested to very low levels Northern elephant seals returned from ~100 to more than 80,000 Japanese sea lion (sub-species) went extinct

43 Demographic stochasticity (N=78)

44 Demographic stochasticity (N=800)

45 Some rules of thumb ~50 individuals allows a population to escape from risk of extinction from demographic variance (in the absence of Allee effects) ~500 effective population size allows a population to escape genetic inbreeding problems In populations of modest size, environmental variance perhaps much more important than demographic Recent recognition that “catastrophic” events or longer term regime shifts may be more important than inter- annual variation

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