MARB 403 Lecture 4

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Video: Pity the Pilot Whale

Short-finned (tropic/temperate) and long-finned (cold-water)

Drive fisheries: herding whales and dolphins to their death

• used to be for human sustinance
• now carried on as tradition
• two primary locations: Faeroe Islands and Japan

Pilot whales are actually a species of dolphin

store oxygen in body and metabolize as needed

slow metabolism: they can shut down non-essential bodily functions when diving

• "dive response" may also be responsible for their miraculous healing ability

Canary Islands: Jim & Sarah Heimlich-Boran study Pilot Whales

• Photo ID of dorsal fin
• 500 animals; 30 pods

very tight-knit, cohesive groups

(usually) Beneficial traits

• forming lifelong bonds
• migrate over vast expansions of ocean
• use sound to find food and maintain cohesion of group

Compassion for Stranded Pilot Whales

Beaching:

• illness
• confusion
• disorientation

Mass strandings:

• occur in different parts of world
• can take place regularity corresponding with migration and geography
• not much understood; theories:
  1. When ill or injured, cetaceans may find beach to die on: provides support and access to air
  2. (cont'd) strong social structure: if one animal beaches, others might follow in blind loyalty
  3. High tide lures whales in, outgoing tide traps them on beach

Golden Bay volunteers (in New Zealand) help return stranded animals back to sea

• latter theory might be cause
• Turn upright, keep cool and wet
• rock back and forth (helps with orientation and wooziness when returning to sea)
• Keep calm until high tide (one whale taken out to call others back out to sea)

Hunting

Warning: Depressing Information!

"The hunt" still popular in Faeroe Islands

• modern community; barbaric activity not needed
• whole pods of pilot whales are herded and slaughtered (incl. calves and pregnant females)
• Excuse for continuation: 400+ yr tradition
• 11.5-hour suffering

Pilot whales could escape, but they huddle together and allow themselves to be killed

Last year was the first year they took false killer whales (Pseudorca crassidens)

• false killer whales are usually tropical

On a similar note, there are older Japanese fisheries that drive:

• Dall's porpoise
• Spotted dolphins
• Common dolphins
• Pacific White-sided dolphins
• Short-finned pilot whales
• False killer whales

Behavioral study performed: such close-knit societies that when in danger, animals tend to group next to the individuals they know best

• mothers and calves will be next to each other
• fathers will be together with youngsters

Effect on population size and abundance?

• Faeroe Islands says that pilot whales are abundant (of course they would say that)
• problems with Faeroe analysis: small sample size and underlying "stock" structure (and how they relate to each other) within population could threaten species

Pollution by pesticides and PCBs (causes reproductive failure)

Hunt will probably continue until species population declines (like in Newfoundlands, pattern repeats itself with frightening regularity)

• Blue whale
• Right Whale
• Gray Whale
• Humpback Whales

International Whaling Commission (IWC) formed to regulate whaling industry

• attitudes have shifted toward protection
• 10-year moratorium on all whaling, but small cetaceans not protected
• IWC now wants to protect all Cetaceans (not just larger whales)

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Orcas

Secondary sexual characteristic: trailing edge of fin grows faster than leading edge, greating "sword" shape

Males usually stay in matriarchy and mate during aggregations of pods or superpods

unknown sexual system (polygyny seems to be probable)

Suggestion that there may be as many as 5 subspecies of Orcinus orca

different pod locations and diet selections

• resident feed on salmon
• transient feed on marine mammals

First cetacean to be identified by dorsal fin and saddle patch

Table 5.1: Differing characteristics of resident and transient killer whales nearshore waters of eastern North Pacific

Resident appear in larger groups

Social Organization

Summary of social organization and genealogy of resident (and potentially transient) killer whales in the study area. No dispersal occurred at any level of organization.

Unit	Composition	Definition	Genealogy
Matrilineal (intra-pod) group	2–9 (μ = 3.6) individuals of mixed age and sex	Group of individuals that always travel together in close proximity to one another. The groups are matrifocal.	Matriline of 1–4 (μ = 2.7) generations.
Subpod	1–11 (μ = 1.9) matrilineal groups	Matrilineal group(s) that almost always (> 95% of the time) travel with one another.	Closely related matrilines; matrilines within subpods are more closely related to one another (e.g. share a common mother) than to matrilines in other subpods and matrilines within pods are more closely related to one another than to matrilines in other pods.
Pod	1–3 (μ = 1.7) subpods	Subpod(s) that travel with one another the majority of the time. Dialects are pod-specific.
Clan	2–10 (μ = 4.8) pods	An acoustic grouping of pods that share one or more discrete calls. Most pods exhibit little preference for traveling with other pods within their clan. Not a social group.	Pods that share a common distant ancestor. Pods within clans with very similar dialects and which tend to travel together are likely most closely related whereas those with dissimilar dialects are most distantly related.
Community	1–3 (μ = 2.0) clans	Pods that associate with one another.	Closed populations.

Optimal group size for caloric intake is about 3

Kin Association:

• Resident: Males and females generally tend to stay with their mothers.
• Transient:
  • Males stay with mother or be solitary ^{similar to sperm whale?}
  • Females join another pod and then form their own pod or return to mother if unable to reproduce ^?

Pilot Whales

info from Japanese and Faeroe Island drives

pregnancies drop around 40

lactation continues for much longer

• alloparenting
• social bonding? A few males aged 13-16 have been found to be nursing (milk in stomach)

Sperm Whales

Southern hemisphere study

"schoolmaster bulls" mate with females frequently

• allowed into societies for only a few days to reproduce during spring months
• stays with group or returns to large bachelor groups

General groups of matriarchies called "mixed schools and small bachelors"

• don't migrate so far (up to 40°S

small groups of males

• "medium bachelors" migrate slightly south (toward 50°S)
• "large bachelors" migrate far south (toward 60°S)
• regroups for spring, fall, and winter months

Structural Aspects of Sperm Whale Mating System:

• alloparenting while parents dive
• cohesiveness for cooperative foraging and avoiding predation
• allowance for prolonged parental care and suckling
• long gestation period and low female reproductive rate
• excess males leads to competition, dimorphism, and polygyny
• males are huge and require more food (that's why they migrate farther south
• males also have a delayed onset of sexual social maturity (25 years; c.f. females 9 years)

Scientist of the Day

"last old white male"

Hal Whitehead

Killam Professor in biology at Dalhousie University

Studies sperm whales and bottlenose whales (also matriarchal deep-divers)

Recommended reading: Cetacean Societies ISBN 978-0226503417

SOCPROG (social program) to analyze animal societies

A colossal convergence between sperm whales and elephants:

• sexual maturity age similar
• similar long gestation and parental care
• similar dimorphism between males and females