So far they haven't found the proverbial smoking gun, but Southeast Alaska and north Pacific researchers are narrowing down the laundry list of possible factors in the decline of western Alaska Steller sea lions.
Since 1992, an estimated $141 million in federal funds have been spent on Steller sea lion research in Alaska. The National Oceanic and Atmospheric Administration is now finalizing its estimated $20 million 2004 budget for multi-agency research on the endangered mammal.
Scientists say there are numerous benefits to seeking answers for the western problem in Southeast's Stellar sea lion population. "It's not as vulnerable a population, so it's OK to try some experimental capture methods. And it's an easier area to work - logistically, and because it's a little more forgiving in terms of weather," said Tom Gelatt, Anchorage-based sea lion research project leader for the Alaska Department of Fish and Game.
Sea lions are notoriously difficult to study because of their isolated environment, their bulk and their speed in the water. But so far, Southeast Alaska Steller sea lions have provided some interesting new information about the health and general biology of the species, scientists said.
Though it has not been conclusively proven yet, Steller sea lion diets appear to be much more diverse in Southeast Alaska than in western Alaska waters, said Mike Sigler of the National Marine Fisheries Service Auke Bay Laboratory in Juneau.
Nutritional problems are a leading theory for decline, but others have proposed a multitude of possible factors, such as increased predation by killer whales or ecosystem shifts wrought by climate change.
Some findings are puzzling. For example, on average, individuals in the declining population of sea lions are bigger and heavier than their Southeast counterparts, Gelatt said.
Sigler and several other scientists are publishing a study of eulachon and sea lion interactions in nearby Berners Bay this fall.
Oil-rich eulachon, a type of smelt, are like "Big Macs" for sea lions, Sigler said. The Berners Bay study shows that the eulachon runs in April-May in 2002 and 2003 provided much more food-derived energy than any prey species reported in the north Pacific except northern lampfish, which inhabit deep water and are less predictable prey.
The eulachon "pulse" may be an important factor in breeding, because pregnant sea lions are in their third trimester while they are foraging in Berners Bay and their fetuses are putting on the most weight. "The (mothers) are trying to build their energy stores," Sigler said.
A crucial Steller sea lion initiative will reach a major milestone in late 2004.
The Department of Fish and Game is finalizing a draft version of the Steller Sea Lion Recovery Plan, said Bob Small, Juneau-based chairman of the recovery team and marine mammal coordinator for the agency.
The recovery plan is required because of the mammal's endangered status. The plan has been under development for two-and-a-half years and it will identify the main threats to the mammal, quantify those threats as well as possible and lay out possible actions that should be taken, Small said.
So far, one controversial protective measure has been to restrict the trawl fisheries in western Alaska. "The plan will not go into the details of fishery management," Small said.
The recovery plan may be submitted to the National Marine Fisheries Service by early 2005, Small said.
He added, "There's still some uncertainty, but signals are out there telling us what are the threats. The team has invested a lot of time and energy in the work. It will be up to NMFS to take up (the plan) as they wish."