CONTINUING FALL OF SEAL POPULATION IN SOUND BAFFLES EXPERTS

By NATALIE PHILLIPS
Daily News reporter

ANCHORAGE- The number of harbor seals in Prince William Sound is still dropping and scientists who are analyzing blubber and whiskers in the search for clues can't figure out why.

But studies this summer suggest that the declining populations south of Kodiak Island have leveled.

That's what biologists told about 140 scientists attending the three-day American Association for the Advancement of Science conference in Valdez, which ends today. On Friday, scientists talked about ''Lessons from the Exxon Valdez,'' the 1989 oil spill that left 11 million gallons in the Sound.

While harbor seal numbers in Southeast Alaska have long been stable or increasing slightly, their numbers in the Sound and off Kodiak Island have been dropping dramatically for 20 years. The spill only accentuated the problem, said Brian Fadely, a researcher at the School of Fisheries and Ocean Sciences at the University of Alaska Fairbanks.

''There's lots of speculation and work being done on finding out what is the cause,'' Fadely said.

So far there are no answers, but a favored theory is that there has been a reduction in the amount of or quality of food, Fadely said. To prove that theory, scientists have been looking at seal body conditions, weight and blood chemistry.

However, a comparison of 1960s and 1990s data on length, body weight and blubber thickness of seals showed no significant difference. Scientists also found that Sound seals have a slightly higher blubber density than Southeast Alaska seals. That means the fat has more lipids, which provides better energy storage and indicates they are in better condition, Fadely said.

Amy Hirons of the Institute of Marine Science at the University of Alaska Fairbanks told the audience she started collecting seals' visbrissae, or whiskers, in 1993 to look at their chemical content and growth rates. She hopes to find out if something in the food web has changed that would explain the decline.

Steve Trumble, also of the institute, said he started a study this summer that will expand upon Fadely's study of harbor seals. He is analyzing the blood chemistry of seal pups in the Sound and near Tugidak Island, south of Kodiak. Trumble pointed to another study completed this summer that found seal numbers have stabilized at decreased levels near Tugidak. So far, Trumble has not found any significant difference in the blood chemistry of the Sound and Tugidak seal pups.

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