Environmental Science Program Seminar - 11/16/2000 - Val Veirs
Population Dynamics of the Northern Resident Orcas
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Population Dynamics of the Southern Resident Orcas

• Capure of Southern Residents (1965-1976) for marine parks such as Sea World


• Limited food supply: It is assumed that declining salmon and
bottom fish populations affect the ability of the whales to find food.
Puget Sound chinook were listed under the Endangered Species
Act last year. Bottom fish are being studied for possible listing.
Studies regarding the whales' ability to find fish are needed.

• Toxic chemicals: The blubber of the southern residents has been
found to contain unusually high levels of long-lived chemicals called
polychlorinated biphenyls, or PCBs. Once commonly used in
electrical transformers, PCBs are believed to affect reproductive
and immune systems.

• Whale watching: Some researchers argue that whale watching is
probably the least of three major impacts, but it is the only one that
can be fixed in a short time.

Synergistic effects
The total effect on whales may be greater than one might think.