Study: Seals vacate ice floes when ships approach; long-term effects are unclear

Posted: Friday, March 28, 2003

A new study says harbor seals near Yakutat are more likely to vacate their ice floes when cruise ships approach them, but more analysis is needed to show whether cruise ships are harming the seal population.

Researchers from the Alaska Fisheries Science Center's National Marine Mammal Laboratory observed the behavior of seals in Disenchantment Bay, located inside Yakutat Bay, between May and August 2002.

According to the draft report, the closer cruise ships come to seals, the more likely the seals are to enter the water. The study found that 75 percent of seals entered the water when ships passed within 200 meters (656 feet), compared with less than 10 percent entering the water at distances more than 600 meters (1,968 feet).

The study was requested by the North West CruiseShip Association and the Yakutat Tlingit Tribe, which have been locked in a debate about how far cruise ships should venture into Disenchantment Bay.

The tribe has argued the cruise ships disturb the seals during their late spring-early summer pupping time, and that it has affected the seal population and, ultimately, the tribe's subsistence hunting.

The cruise ship association and the tribe requested the study to have scientists settle the question of whether the cruise industry harms the seal population.

The draft report doesn't answer that question. Researchers say the answer lies in the two parts of the study that have yet to be analyzed.

"From the other data that we collected we hope to be able to decipher whether there is a population shift in distribution of the animals in the bay," said Kaja Brix, a wildlife biologist with the National Oceanic and Atmospheric Administration's fisheries division.

That data will be analyzed within a year, she said.

According to the draft report, 168 cruise ship visits were scheduled for Disenchantment Bay last year, representing a 7 percent increase over the year before. The bay received as many as five cruise ship visits a day, according to the study. The study also said cruise ship traffic could increase in Disenchantment Bay if more cruise lines are banned from Glacier Bay National Park or if tighter restrictions are imposed upon the number of cruise ships allowed in the bay.

Bert Adams Jr., the Tlingit tribe's environmental coordinator, says that while it's too early to tell from the data whether the tribe's suspicions have been proven scientifically, he is certain there are fewer seals now than when he was younger.

"I've been hunting seals since I was 9 years old, and earlier in my years ... it was pretty easy to find seals and hunt seals. The seals were surrounding us; you're talking 50 or 60 at a time. The last five years when I've gone out, I've noticed it's a lot tougher to find where they're at," he said.

John Hansen, executive director of the cruise ship association, agreed that it's too early to draw conclusions from the data. But he did say the cruise lines in his group keep their ships 1,500 feet away from ice floes that have seal pups on them.

"That's been our operating practice for the last year and certainly will continue again this year," he said.

Masha Herbst can be reached at

Trending this week:


© 2018. All Rights Reserved.  | Contact Us