The impressive Steller sea lion (Eumetopias jubatus) is the third largest pinniped, after the walrus and the elephant seal, and a top fish predator. The Steller sea lions’ habitat extends around the North Pacific Ocean from eastern Japan and Russia, through the Aleutian Islands, Bering Sea, Gulf of Alaska, and down the west coast of North America to Central California. However, despite its expansive range, the entire Steller sea lion population breeds at only a handful of rookery sites where the animals haul out to give birth to their young.
Georg Steller—whom the Steller sea lion was named after—described the species in 1741 after being shipwrecked on an island in the North Pacific. He called the animals “sea lions” because the males’ tawny mane and bellowing roar reminded him of African lions. Long before this discovery, however, the native Aleuts had been intimately familiar with “Steller’s” sea lions, which they called qawan, and had relied on them for thousands of years as a source of food, clothing, and even transportation, as they lined their kayaks with the sea lions’ waterproof skins.
As modern industrial fisheries intensified in Steller sea lion habitat—without any management enacted to protect sea lions from shootings, entanglements, and competition for food with commercial fisheries—the sea lion population declined rapidly. The population of Steller sea lions, most living in Western Alaska, may have been as large as 300,000 animals through late 1970s, but by the 1980s the population had quickly decreased by half. As a result, Steller sea lions were listed under the Endangered Species Act in 1990, and due to genetic distinction, the population was eventually divided into western and eastern stocks for management purposes. By 1997, the western stock of Steller sea lions—which had declined more than the eastern stock and was continuing to decline—was classified as endangered, while the eastern stock was listed as threatened. By 2000, the western population had reached its lowest point with an estimated 42,500 animals remaining, a decline of more than 80% from historic levels.
Since first listing the species under the Endangered Species Act, the National Marine Fisheries Service (NMFS) has consistently concluded that the Alaskan groundfish fisheries reduce Steller sea lion prey resources. NMFS further concludes that prey removal by fisheries in critical habitat (areas and prey resources deemed essential for the recovery and survival of endangered and threatened species) is likely to reduce the ability of that habitat to support sea lions, and that a sustained reduction of prey resources across an ecosystem can reduce the carrying capacity of the population, or the number of sea lions that can be supported by available resources in the surrounding environment. In other words, vast removals of the sea lions’ food make it difficult for them to survive and thrive. Despite these findings, the National Marine Fisheries Service continues to authorize high levels of fishing in and around areas that Steller sea lions call home.