Up close, the North Pacific’s Steller sea lions are unforgettable: 10 feet long, one-ton heavy, golden-maned, and roaring like lions. Viewed from a distance, they’re a giant worry for everyone with an interest in the economic or environmental well-being of Alaska’s waters. The Bering Sea and Gulf of Alaska comprise America’s (and nearly the world’s) richest and healthiest fishery. But a long, mysterious drop in the population of Steller seals has fishermen, federal officials, conservationists, and lawyers looking at the fishery as a possible cause. They have become the Bering Sea’s spotted owls, its “indicator species.” (Seabirds, harp seals, and fur seals have also declined in the region, but not so perilously as the Stellers.)

The big sea lions have been moving toward that status for nearly a decade, ever since the National Marine Fisheries Service (NMFS) declared them a “threatened species.” Now that designation has hit home. After changing its designation of the Stellers from “threatened” to “endangered,” the NMFS earlier this month found that Alaska’s $670-million pollock fishery (the mainstay of Seattle’s trawler fleet, and a major surimi and fish-and-chips source) “jeopardizes” the declining Stellers, and ordered that the fishery be reconfigured to protect them.

The North Pacific Fisheries Management Council, the industry’s instrument of self-regulation, was then deputed to come up with specific protection measures. Four weeks ago, it approved a complicated recipe of changes that will essentially spread out the pollock fishery, now concentrated in a few short, frantic bursts, over more months and reduce fishing in the designated sea lion “critical habitat.”

True to form, these measures please none of the parties involved. Greenpeace USA and the Earth Justice (formerly Sierra Club) Legal Defense Fund, which have sued the feds on the Stellers’ behalf, call them misdirected and inadequate. “It’s messing around the status quo,” complains Sue Sabella, director of Greenpeace USA’s Oceans Campaign. “They don’t spread the fishery out enough geographically or in time.” Indeed, the Fisheries Council still allows pollock fishing in winter, when the sea lions are most hungry and vulnerable (it’s also when the pollock, bearing roe, have the most cash value). And it still allows most of the take to come from “critical habitat”—which happens to be where the most productive fisheries are.

Washington’s Sen. Slade Gorton further raised environmentalists’ ire in November, when he joined Alaska’s congressional delegation in signing a letter to the US Commerce Department, NMFS’ parent agency, questioning the restrictions NMFS was then expected to recommend and urging that the job be turned over to the Fisheries Council. It was.

Even so, the fishing industry is howling that the Council-mandated restrictions will exact “real pain”—perhaps to the tune of $100 million a year. And the factory trawler sector, which is based in Seattle, also fears that the Alaskan interests that dominate the Fisheries Council will use the sea lion rules to shift more of the pollock allocation over to Alaska-based fishers. “It opens an avenue to the Alaskanization of the fishery,” laments Edward Richardson, an economist with the At-Sea Processors Association, which represents the Seattle trawlers.

Divided as they are, the rival fishing factions share one contention: that the new restrictions won’t help the sea lions because they’re based on a fundamental scientific misconception, or misrepresentation. The Fisheries Council itself nearly concedes the point in its preamble to the restrictions when it says, “There is considerable scientific uncertainty regarding the relationships between the pollock fisheries and the Western populations of Steller sea lions.”

The question—a first-class biological mystery that has puzzled researchers for two decades—is this: What exactly is driving Alaska’s sea lions to the brink? A consensus is forming on the one broad point that their main problem is nutrition rather than disease, pollution, fish-net kills, or killer-whale predation. But are the mighty Stellers not getting enough fish to eat, or are they getting the wrong kind of fish? The question is not academic—in the former case, you can blame the pollock fishery. In the latter, blame God and leave the fishery alone.

THE CASE AGAINST THE FISHERY rests on what seems a strong correlation. For nearly three decades, pollock has been the Western Alaskan Stellers’ prime food. During that time, the pollock catch has grown by leaps, from zilch to well over a million metric tons each year. The pollock biomass grew likewise, peaked in the early ’80s at about 17 million tons, then fell to half that. And the Western sea lions have plunged from about 110,000 in the late ’70s to a little over 20,000 today. Meanwhile, a separate stock of about 34,000 Stellers lives in southern Alaska, British Columbia, Oregon, and California—outside the pollock zone. They’ve fared much better, and even increased slightly in some places.

QED, say the environmental groups. See you in court.

But the picture is more complicated than that. Other studies—some of them controversial, industry-sponsored, and unreviewed—present an intriguing alternate explanation of the Stellers’ decline, and invoke other striking correlations. Pollock have only recently come to dominate Alaska’s waters and fisheries. Until the 1970s, when their numbers exploded, they were a minor part of the ecosystem. The pro-fishing side attributes this to cyclical climate and ecosystem change, with warming waters and less nutrient upwelling—conditions that suit pollock but hammer previously dominant pelagic species such as herring and capelin. (Other authorities—including NMFS—credit this mainly to past overfishing of herring.)

In any event, the sea lions were forced to switch to pollock, and consequently suffered for it. The reason: Oily cold-water fishes like herring and sandlances are much more energy-rich than pollock, a low-fat marine “junk food.” Ergo, the Stellers are starving with their bellies full.

Industry advocates—along with BC researcher Andrew Trites, the main proponent of this theory—push it even farther. It seems that adult pollock are a main eater of juvenile pollock (nature isn’t always pretty). Sea lions (and seals and seabirds) also supposedly prefer the smaller fish. If there were fewer adult pollock, this argument goes, there would be more juvenile pollock and more herring. Therefore, humans should take more pollock—for the sake of the sea lions.

Greenpeace USA’s Sabella and other sea-lion defenders sneer at what she calls “the Twinky defense of the fishing industry”—called, in more polite circles, “the junk-food hypothesis.” “I find it hard to believe that the Steller sea lion is suffering from some sort of eating disorder,” quips Sabella. Earth Justice attorney Doug Ruley notes that though Stellers catch more small than adult pollock, the big ones are still a larger food mass for them.

But Trites does cite some experimental confirmation of his junk-food hypothesis: Stellers that were fed only pollock at the Vancouver Aquarium lost weight (a pound a day), even as their metabolisms dropped. Both effects could hurt their chances of surviving and reproducing in the wild.

NMFS’ official “Biological Opinion” on the sea lions’ plight concedes merely that the hypothesis “is a meaningful area of investigation, but it is premature to form any conclusions. . . . Sea lions must survive with the prey resources that are available.” Pollock “may not be optimal,” but they’re better than nothing.

There’s the regulatory dilemma. If the junk-food hypothesis is correct, then allowing the sea lions more pollock only consigns them to more slow starvation. But to further reduce the food supply of an imperiled species seems a brazen violation of the first principle of conservation as well as medicine: First, do no harm.

The At-Sea Processors’ Richardson charges that NMFS bought off on the overfishing explanation not out of scientific conviction but in order to stave off the Greenpeace and Earth Justice lawsuit. Tim Ragen, coordinator of the NMFS Steller Sea Lion Recovery program, replies, “I’d be misleading you if I said we weren’t aware of the lawsuit. But we were starting to work on these issues before the lawsuit was filed. We’re simply trying to do the right thing.”