Cetaceans (order Cetacea) Whales, Dolphins and Porpoises Two kinds of whales and dolphins...

Cetaceans(order Cetacea)

Whales, Dolphins and PorpoisesTwo kinds of whales and dolphins

Mysticetes= Baleen whalesOdontocetes= Toothed whales, porpoises and dolphins

Killer whales (Orcinus orca)

Distributed world-wideLive in matriarchal groups called pods

Off-shore and inshore pods have different pod structuresSpecialize in their feeding habits & hunt in groupsLife expectancy of 30 and >50y for males and femalesSexual dimorphism – males larger, up to 10m w/ 2m dorsal finGestation 17mo, then nursing for 18mo, high infant mortalitySexual maturity at 10-15 w/ adolescent periodMenopause in females at ~40y

Distribution of Killer Whales in N PacificKrahn, M.M., et al. 2002. 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

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 1000-1250 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

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, 1945-1967

Aquarium trade capture 1965-1972

4 Sympatric Communities

Offshores

Transients

Northern Residents

Southern Residents

Differences in dorsal fins

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

Fre

quen

cy (

Hz)

Ecolocate, sing & whistle

echolocation

singing

whistle

Lets look at each group

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Fin shape, animal size Acoustic differences Actively avoid the fish-eaters Unpublished genetic data suggests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 PS, @25 individuals in <10 pods

ID’d from ~175 known individuals Attempt to watch Video

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

Hunting video

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

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

Offshore encounter

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

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

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

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 1964-1972

Pod Structureof 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

Washington

Vancouver Island

British Columbia

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.

SR usage of Haro Straits region

J pooled K pod L pod

Data analysis by Donna Hauser, data from the international sighting network

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

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

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

Lolita

Last living capture from the Southern Residents

Currently at Sea World, Florida

Current SR population tally

Is the population rebounding from its most recent decline?0

20

40

60

80

100

120

1970 1975 1980 1985 1990 1995 2000 2005

Year

# in

SR

Po

pu

lati

on

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

Excerpted and updated from:

Dynamics of small populations

A presentation provided by:

Paul R. WadeNational Marine Mammal Laboratory

Alaska Fisheries Science Center

NOAA Fisheries

Seattle, WA

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

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

Populations driven to low numbers face a riskof 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

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

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

0.000

0.010

0.020

0.030

0.040

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Population level (as fraction of K)

Pop

ulat

ion

gro

wth

per

cap

ita(n

umbe

rs o

f ani

mal

s/po

pula

tion

size

)

Allee effect

No Allee effect

Allee effect

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

PVA estimates for the extinction of SR

Full record, no catastrophes Full record, 2% catastrophe

1992-2000 record, no catastrophes 1992-2000 record, 2% catastrophe

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

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

0.90

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1.00

1973 1977 1981 1985 1989 1993 1997 2001

Year

Sur

viva

l 6 year model Annual

Environmental variance in survival

Hard to predict fate of a particular population2 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

Demographic stochasticity (N=78)

0

50

100

150

200

250

2000 2020 2040 2060 2080 2100

Year

Pop

ulat

ion

size

0

500

1000

1500

2000

2500

2000 2020 2040 2060 2080 2100

Year

Pop

ulat

ion

size

Demographic stochasticity (N=800)

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