[env-trinity] Researchers Link Chinook, Orca Populations

[Josh Allen]

http://news.yahoo.com/s/ap/20060405/ap_on_sc/northwest_orcas 


Researchers Link Chinook, Orca Populations


By PEGGY ANDERSEN, Associated Press Writer Tue Apr 4, 10:36 PM ET 

SEATTLE - The killer whales that chase salmon in this region's inland
waters feed almost exclusively on chinook, to the extent that the orca
population ebbs and flows right along with that of the West Coast's
largest and longest-lived salmon, researchers said Tuesday. 

The whales settle for chum salmon for six to eight weeks in the fall,
when most of the chinook are gone, John Ford of Canada's Department of
Fisheries and Oceans said at the 2006 Symposium on Southern Resident
Killer Whales, a joint effort of his agency and the U.S. National Marine
Fisheries Service.

Between 1996 and 2001, Ford said, sharp drops in the region's chinook
runs correlated with declines in the northern and southern resident orca
populations, as the inland killer whales of Canada and the United States
are called.

Orca mortality was 300 percent higher than expected, Ford said, and
difficult to link to other known stressors.

"It was a bit of a surprise to us," he said.

Both the U.S. and Canadian orca populations have been declared
endangered, and the findings suggest salmon managers may want to set
aside some chinook for the whales, he said.

"Chinook are what drive these animals," Ford said, even when other
seemingly adequate salmon species may be far more abundant.

Many of the region's salmon runs are also considered endangered.

Killer whales may have come to prefer chinook over the centuries because
the runs extend from April through October, he said. They spawn at
different ages, and non-migratory chinook can be found in the area
year-round. Chinook live as long as six years, longer than other salmon
species, and can weigh up to 70 pounds. They also are fattier than other
salmon species.

"I came in here today thinking killer whales would eat the salmon that
were most abundant, but I'm finding that's not the case," said salmon
researcher Jeff Haymes of the Washington state Department of Fish and
Game, who also spoke about chinook populations at the second day of the
three-day conference.

Longtime orca researcher Ken Balcomb of the Center for Whale Research
addressed the mystery of where the resident orcas spend the winter
months. The southern residents have been seen as far south as Monterey,
Calif., and as far north as Canada's Queen Charlotte Islands.

"Now I know they hang around the core area till the chum run out ... and
then go work chinook out on the coast," he said, laughing.

Defining orca habitat for protection is one of the tasks faced by NMFS
under the Endangered Species Act.

"It's a moving target," Balcomb said.

When chinook numbers are down, orcas work harder to find them, said
University of Washington researcher Shannon McCluskey, who studied orca
movements and population in relation to salmon populations.

In the late 1990s, when runs were down, orcas spread out beyond the San
Juan Islands, where the state's three resident orca pods are based. In
the early '90s, when chinook numbers were up, they stayed closer to
home.

Orcas, actually a kind of dolphin found in all the world's oceans, feed
on 200 prey species, Ford said. Transient orcas, which live along the
coast, prefer marine mammals. Offshore orcas mostly eat fish, including
sharks.

Other researchers spoke about pollution threats from toxins such as
long-lasting PCBs, or polychlorinated biphenyls, which have been banned
since the 1970s but persist in orcas and other top predators; and
fire-retardant PBDEs, polybrominated diphenyl ethers, which are still
produced. 

The impact of vessel traffic also was addressed. 

___ 

On the Internet: 

Fisheries Canada: http://www.pac.dfo-mpo.gc.ca
<http://us.rd.yahoo.com/dailynews/ap/ap_on_sc/storytext/northwest_orcas/
18624368/SIG=10ubmbb3f/*http:/www.pac.dfo-mpo.gc.ca>  

National Marine Fisheries Service: http://www.nwr.noaa.gov/
<http://us.rd.yahoo.com/dailynews/ap/ap_on_sc/storytext/northwest_orcas/
18624368/SIG=10q7k9ip7/*http:/www.nwr.noaa.gov/>  

Orca Network: http://www.orcanetwork.org
<http://us.rd.yahoo.com/dailynews/ap/ap_on_sc/storytext/northwest_orcas/
18624368/SIG=10svdve2g/*http:/www.orcanetwork.org> 


 


 

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