Ninety percent of the world’s sea otter population lives in coastal Alaska, over 8,000 of them in Glacier Bay. By 1900, sea otters had been exterminated from nearly the entire North Pacific Ocean. No populations existed from Prince William Sound, Alaska to Big Sur, California.
The influence of sea otters in rocky-bottomed nearshore marine communities has been widely studied, and their role in controlling sea urchins and thus allowing the development of kelp forests is well known . In Glacier Bay, substrates suitable for the establishment of kelp forests are not common—much of the shallow water seafloor consists of mud, ...
The sea otter population in Glacier Bay grew from five animals in 1993 to 8,508 in 2012. This is an average annual growth rate of 42%, which far exceeds the estimated maximum reproductive rate of increase of 24% per year for the species.
To survive in their cold-water environment, sea otters must consume 20-30% of their body weight in food daily.
Sea otters began to colonize Glacier Bay proper in 1993. Ecologists and park managers hailed their return as a conservation success story but also anticipated profound changes in the structure of the nearshore marine community due to predation by this top-level carnivore.
Benthic invertebrates, such as clams, urchins, crabs, and snails, were collected by divers, measured, and returned to the seafloor. This study compared the fauna of intertidal and subtidal habitats before and after their re-occupation by sea otters.
In 1911 the International Fur Treaty provided the few hundred remaining sea otters with their first measure of protection. In the late 1960s, 403 sea otters were transplanted to several locations in Southeast Alaska, and the population began a remarkable recovery.