Prince William Sound Orcas May Need Extra Protection

JUNEAU, Alaska, April 17, 2003 (ENS) - A dwindling group of killer whales, or orcas, that pass through Prince William Sound Alaska may receive additional protection under federal law. NOAA’s National Marine Fisheries Service is reviewing a petition to designate the AT-1 group of orcas transiting Prince William Sound as depleted under the Marine Mammal Protection Act. The agency received the petition from a coalition of conservation groups on November 13, 2002. Agency officials found the petition may have merit.

The petition was presented by the Alaska Center for the Environment, Alaska Community Action on Toxics, Center for Biological Diversity, Coastal Coalition, Defenders of Wildlife, the Eyak Preservation Council, and the National Wildlife Federation.

The petition listed genetic, behavioral, ecological and management reasons for designating the AT-1 group separate from the general group of transient killer whales in the eastern North Pacific. NOAA Fisheries is conducting a status review of the Prince William Sound killer whales, which will address whether the AT1 group is a separate stock under the Marine Mammal Protection Act and whether this potential stock is depleted.

The AT-1 group once numbered 22 animals, but now contains only nine whales, including four females. The AT-1 whales have been observed feeding on harbor seals and porpoises in Prince William Sound and Kenai Fjords in Alaska, but no new calves have been sighted since 1984.

“Regardless of the outcome of the population status review, we are, and have been, concerned about this group of killer whales,” said Ron Berg, assistant administrator for NOAA Fisheries in Alaska.

Male orca in Prince William Sound (Photo courtesy Alaska Fisheries Science Center)

Resident and transient orcas have different eating habits, calls and genetics. The AT1 group is currently considered part of a larger population of 346 transient killer whales in the eastern North Pacific. Prince William Sound and Kenai Fjords are also home to about 362 resident killer whales.

The main distinguishing feature between the residents and transients is their mutually exclusive prey base, with residents eating fish and transients consuming marine mammals. These two types of killer whales may be found in overlapping geographic ranges; however, they do not interact., says NOAA Fisheries in its Federal Register Notice of the petition review. The primary social structure of both groups is the matriline, dominated by a matriarchal female, her offspring, and direct descendants.

The AT1 killer whales are transients. In National Marine Fisheries Sservice marine mammal stock assessment reports, AT1 killer whales are currently included with two other groups of transient killer whales in the eastern North Pacific stock.

Although the range of these transient groups overlap, they do not associate. The Gulf of Alaska and AT1 whales inhabit the waters of Alaska exclusively. The Gulf of Alaska transients are occasionally found in Prince William Sound, whereas the AT1 group inhabits the waters of Prince William Sound and the Kenai Fjords and has not been observed elsewhere.

In their petition, the groups noted that the AT1 group is readily distinguishable from other transient killer whales in the Gulf of Alaska in hunting and communication patterns. Whereas other transient killer whales prey extensively upon Steller sea lions, AT1 transients prey primarily on harbor seals and Dall's porpoise. The petitioners concluded that these genetic and behavioral differences are sufficient evidence upon which to identify the AT1 group as a separate population stock.

The petitioners also noted that the Alaska Scientific Review Group, an independent advisory group established according to the Marine Mammal Protection Act, has recommended that the National Marine Fisheries Service recognize the AT1 group as a separate stock.

Following the status review of the AT-1 group, the agency will publish its findings, which are due 210 days after the petition was received, on June 11.

If NOAA Fisheries finds that the stock is separate and depleted, the agency will consider development of a conservation plan for what would be the newly designated AT-1 stock of killer whales.