Sea Otter Crash
INTRO: First it was sea lion populations that started to disappear along the rocky coast of southwest Alaska's Aleutian Islands. Next came harbor seals. Now scientists say sea otter numbers in the Aleutians are so low that they're likely to be listed as an endangered species before the year is out. As Doug Schneider reports in this week's Arctic Science Journeys Radio, scientists now must figure out how to save Alaska's most adorable marine mammal.
STORY: The story of Alaska's sea otters reads like many of the boom-then-bust stories of the far north. In the 1740s, just before the Russians showed up in what is now Alaska, sea otters were thought to number in the hundreds of thousands. Over the next 170 years, hunting by the Russians, and then the Americans, pushed the sea otter to the brink of extinction. By the time hunting was banned in 1911, sea otters were all but extinct across Alaska.
To help sea otters recover, scientists in the 1960s transplanted several hundred animals from surviving groups in Prince William Sound and the Aleutian Islands to Southeast Alaska, where the situation was most dire. Soon, sea otters were once again thriving at or near their historic highs across the state. According to the Alaska Department of Fish and Game, sea otters in the Aleutians alone numbered around 100,000 animals by the 1970s.
But since 1990, sea otter numbers along the remote, 1,000-mile-long Aleutian Island archipelago have taken a turn for the worse. According to recent surveys, just 30,000 sea otters are left in the Aleutians. Sheltered bays that once teamed with sea otters are now eerily silent. Rosa Meehan is chief of marine mammal management with the United States Fish and Wildlife Service, the agency in charge of sea otters.
MEEHAN: "In southwest Alaska, from Kodiak Island on out the Aleutians, the population has declined dramatically. We did an aerial survey that covered the whole of the Aleutians in 1992, and then we did that same survey again in 2000. And what we found was an overall 70 percent decline in the area. As a result the Fish and Wildlife Service has identified sea otters in that region as a candidate for listing under the Endangered Species Act."
In preparation for the listing, the Fish and Wildlife Service will meet in April with scientists, fishermen, Alaska Natives, and environmental groups, to develop a research plan aimed at prioritizing the steps needed to help sea otters recover, or at least stem the decline.
MEEHAN: "We're now in a situation where we've got a population that's at such a low level that we need to look at what the mortality factors are now that may be in effect. Because that could be very different from what caused the decline. We want to sort that out now and use that understanding to identify what research needs to be done and also identify what potential management action we could take."
Meehan says it's probably not a coincidence that sea otters are declining in the Aleutians, the same place that has seen startling declines in the number of Steller sea lions, harbor seals, as well as fish and seabird species. As with the sea lion, scientists don't know for sure what's causing the sea otter decline. Researchers have looked at reproduction, disease, food availability, Native hunting, and fishery interactions, and none seem to be directly responsible for the crash. Instead, Meehan says all the signs point toward predation by killer whales and possibly sharks.
MEEHAN: "Such a steep decline over such a broad range fits a predator model. The culprit that has been identified is killer whales."
But while predation may be scientists' best guess, Meehan says there isn't any hard evidence that killer whales or sharks are to blame for the crash.
MEEHAN: "We don't have a better explanation. But it's an uncomfortable explanation because it's hinged in large part on, 'Well, nothing else seems to fit.' And so it's something we want to look at in greater detail."
Unlike efforts to help the Steller sea lion recover—efforts that have resulted in restrictions on commercial fishing—Meehan says it's not likely the agency will ask for major changes in the way Alaska's crab and groundfish fisheries are conducted.
MEEHAN: "We don't think (sea otters) have a direct interaction with fisheries, whereas with sea lions there's a potential direct competition with fisheries for resources. Well, we don't have that with sea otters. Sea otters live near shore and their primary prey in the Aleutians is sea urchins. We're not closing the door and saying there's no fishery interactions. We want to look at it in much greater detail. There are some trap fisheries, particularly for cod, that take place. Some of that is done in shallow waters. That's the type of fishery where a sea otter may get trapped in a pot that's put out for cod, and then drown. In the past there have been some sea otters taken in the pot fisheries."
Given the sea otter's history of amazing comebacks, Meehan believes that the Aleutian sea otter will, given time and maybe some help from scientists, weather this latest storm in their survival.
MEEHAN: "If we can keep the mortality at a level that still allows the population to grow, then I have every confidence that sea otters have the capability to rebound and reestablish themselves in their range."
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.
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Thanks to the following individual for help preparing this script:
Rosa Meehan, Chief
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks. The shortcut to our ASJ news home page is www.asjnews.org.
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Related Web sites
Marine Mammal Center: Sea otters
ABC News: Sea otter crash
ASJ story: Sea otters rebound in Southeast Alaska
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