module 4: marine mammals 1.polar bears 2.seals, walrus, sea lions 3.toothed whales (beluga, narwhal,...

Module 4: Marine Mammals

1. Polar bears

2. Seals, walrus, sea lions

3. Toothed whales (beluga, narwhal, killer whales, etc.)

4. Baleen whales (humpback, bowhead, grey, northern right, etc.)

Key Biological Traits

• Large space requirements

• Low reproduction potential

• Long life

• Risk of bioaccumulation of organic pollutants

• Sensitive to over exploitation

Management Difficulties

• Poor estimates of population size and vital rates (reproduction, survival, dispersal)

• Inter-jurisdiction distribution

• Difficult to regulate harvest (subsistence and commercial)

• Highly political in nature

Terms and Concepts

Cetaceans– Mammal species such as whales, dolphins, and

porpoises

IWC– International Whaling Commission

MMPA– Marine Mammals Protection Act (U.S.A.)

Polar Bears

Polar Bear Overview

• Depending on seals (ringed seals and bearded seals)

• Distributed in distinctive stocks

• Subsistence/cultural hunting

• Subject to an international agreement on conservation

• Token sport hunt (in Canada only)

Ringed Seals

Ringed Seal Overview

• Widely distributed (5 million)

• Feed on fish (Arctic cod) and “Arctic shrimps”

• Most important species for subsistence hunting (Inuit)

• Most important for clothing

• Fairly resilient to harvest

Distribution of Ringed Seals

Harp Seal

Distribution of Harp Seal

Harp Seal Overview

• Commercial hunt in spring (under quota)

• Increasing in population size

• May affect fish populations

• Source of debate

Bearded Seal

Bearded Seal: Overview

• Heterogeneous distribution

• Like thin ice, or ice flow

• Secondary prey for polar bears

• Excellent skin for ropes and moccasins

Walrus

Walrus Distribution

Walrus Overview

• Two stocks: Atlantic and Pacific

• Source of ivory (art work)

• Gregarious in distribution

• Mollusk eaters (some prey on seals)

• Excellent skins for ropes!

• Hunt in Alaska highly regulated

Beluga Whale

Beluga Whale

Beluga Whale Populations: Circumpolar

Beluga Whale Populations: Canada

Beluga Whale Overview

• Large movements (distinct stocks)

• Important for subsistence hunting (delicacy food)

• Hunted under quotas (by local people)

• Rich in Vitamin C (scurvy)

• Major conservation issues in some regions

Narwhal

Narwhal: Overview

• Large seasonal movements

• Hunted for food and tusks

• Traditional hunt only (under quota)

Narwhal Populations

Other Whales

Other Whales: Overview

• ~50 humpbacks harvested per year in Chukchi Sea by Alaska Inuit

• Few (1-2) bowheads harvested by Eastern Arctic Inuit

• Subsistence hunt continued to be impaired by past overuse of stocks (commercial whaling)

Marine Mammals - People

• Long term dependency of northern people on marine mammals (seal hunters)

• Recurring issues of conservation and public debates

Commercial WhalingPhase I: The Basque Fishery (Spanish)

– 1300 to late 1500 A.D.

Overview

• Focused on right whales (local depletion of coasts of Europe)

• Expanded up to Grand Banks near Newfoundland

• By late 1600s, right whales were almost exterminated

Phase II: The Atlantic Arctic Fishery

Overview• Focused on bowhead whales in North Atlantic• Early 1600sLate 1800s• Involved many shore stations• Move from Svalbard, Davis Strait, Baffin Bay, to

North water• Risky but lucrative (£3500 a ton for whale bones)• In 1910, 10 whaling ships hunted the Arctic: 18

pilot whales, 389 belugas, 1697 walruses, 4549 seals, 242 polar bears, and no bowhead whales

Phase III: Pacific Arctic Fishery

Overview

• U.S. whalers shift attention to North Pacific• First, Pacific northern right whales (largely

depleted by 1850)• Next, Pacific bowhead whales in Bering Sea (150-

200 whaling ships, up to 2700 bowheads killed in 1852)

• First whaling ships with steam engines pushed hunt in North Shores of Alaska (Beaufort Sea)

Overview

• Market collapsed in 1912, which lead to an end of whaling in the Arctic (which “saved” humpbacks)

• In SE Alaska, whaling ended in 1930s

• In 1937, first international whaling agreement

Required Reading

“Thar She Blows: Whaling in the Yukon and Alaska”

(handout)

Modern “Whaling”

Case Study: Steller Sea Lions

Conservation Issues• Slow recovery of most

baleen whale stocks (except gray whales)

• Impair acceptance of traditional hunts by general public

• Atlantic right whales at great risk

• Management of tourismNorth Atlantic Right Whale