Kodiak's Steller Sea Lions
INTRO: Scientists for years have been trying to learn why populations of Alaska's Steller sea lions are crashing in western parts of the state. Near the small fishing town of Kodiak, scientists are teaming up to study the ecosystem that supports sea lions. Doug Schneider has more, in this week's Arctic Science Journeys Radio.
STORY: Local fishing boat captain Dave Kubiak eases his 44-foot boat, the Mythos, into the calm waters of the lee side of Cape Chiniak. Here, a cluster of rocky outcroppings serve as a Steller sea lion haul-out, a few miles from the fishing community of Kodiak, on Alaska's Kodiak Island.
KUBIAK: "Give us a few seconds to drift around. Let the wind establish where we're going to sit before we drop anchor."
Cutting the engines, another sound replaces the drone of the Mythos' diesel engine.
Groaning and bellowing, Steller sea lions lie sprawled on the rocks just yards from the boat. Tired from feeding in the nearby Gulf of Alaska, the sea lions haul themselves out to rest on this and other sites around the island to rest. While it seems like there are a lot of sea lions here, there should be more. Since the 1960s, Steller sea lion populations in the western half of Alaska, roughly from Prince William Sound through the Aleutian Islands, have declined some 80 percent. Where once this region, spanning some 1,500 miles, teamed with hundreds of thousands of sea lions, just a few thousand remain today.
Scientists trying to find the cause of the crash believe young sea lions are most at risk to starvation, predation, and other factors. Here at Cape Chiniak, sea lions appear healthy as they come and go from the rocks.
Brenda Konar is a marine ecologist and research diver at the University of Alaska Fairbanks. She and a team of scuba divers have come to learn why sea lions prefer specific sites as haul-outs. To answer that, she and her divers need to know what there is for sea lions to eat beneath the waves that constantly pound this and other sea lion haul-outs around the island.
KONAR: "We're curious as to whether there are fish available for the youngsters really near to shore. The small Stellers apparently feed and learn how to forage near to shore. So we want to see if there are fish available for them in these nearshore habitats. We also want to compare the nearshore areas with the offshore areas to see if there are similar fish or fewer fish or more fish."
Konar and other divers conduct a kind of inventory of marine life; swimming along the bottom, recording the plants, the fish, even the small crabs and other invertebrates, that live near the island's seven sea lion haul-outs. Some of the dives are as deep as 100 feet, where the frigid 39-degree water and the increased pressure means divers can spend only about 20 minutes on the bottom.
KONAR: "We go down at the given depth and we lay out three 30-meter transect lines, and the fish person counts all the fish along the corridor on that transect line on the bottom, and then coming back in the mid-water. And then is the benthic person assessing habitat. She's actually counting and identifying different algae and invertebrates and different types of shell debris or cobble, these types of things."
All this data will help Konar and other scientists construct a picture of what life is like for young sea lions learning to forage and fend for themselves. What kinds of fish live near these haul-outs? Do sea lions feed close to haul-outs or do the venture further away? Is there even enough food available to sea lions in these places? And how do these conditions change throughout the year?
Konar's research is a small but important part of a much larger effort by university scientists such as Bob Foy, Kate Wynne and Loren Buck to characterize the entire marine ecosystem around the island. The seabirds, the large commercial fish stocks offshore, the whales, the seals, and the complex food web and oceanography that supports these species all are targets of intense research. It's all part of an ambitious project called the Gulf Apex Predator program. Kate Wynne is a marine mammal specialist with the Alaska Sea Grant Program in Kodiak.
WYNNE: "You ask any of us what we want to get at, and they'll all be different. Bob has his own fish questions. The kelp people have their own nearshore questions. I have sea lion questions. The beauty of this is that we are helping each other answer these questions. My particular questions are trying to figure out who's eating what here, and why for instance are harbor seals increasing in number while Stellers are declining? Why are the whales doing really well? Why do they shift in a certain time frame, and are the Stellers doing the same thing?"
Answers to all these questions won't come easy. For the divers, this is their second trip to these haul-outs. Last summer, divers saw numerous fish within the jumble of kelp beds that surround Chiniak and other haul-outs. But on this trip done during the winter, divers saw only a few fish. That could be because area kelp beds are dormant right now. Kate Wynne says sea lions might have to look harder and venture further in winter to find enough food to eat.
WYNNE: "I think they go where the food is. The ones that have had transmitters put on them will dabble around these haul-outs, which is why we're interested in what's available. But when these pups of last summer start foraging on their own, in April or May, they start going out to the canyon edges, at around 100 meters, which is further offshore. But if you're at Chiniak, that isn't that far. It'd be a good spot to be a pup."
Audio version and related Web sites (sidebar at top right)
Thanks to the following individuals for help preparing this script:
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.
Alaska Sea Grant In the News
The URL for
this page is http://seagrant.uaf.edu/news/
Listen to story on RealAudio
Related Web sites
What do you think of ASJ? Take our survey.