Southern Sea Otter Recovery
There's good news and bad news regarding population levels for the Southern Sea Otter (Enhydra lutris nereis).
These cute as a button marine mammals once roamed the near shore kelp forests of the entire West Coast. Their thick fur and general amenability toward the human population but them at odds with the fur hunters of their era.
Population declines led the species to the edge of extinction, and in 1977, they were placed on the Endangered Species List.
Recent surveys by the United States Geological Society, USGS, show population decreases for the population that lives along Coastal California.
The numbers are significant because scientists have used the number of 3,090 individuals, for three consecutive years, as the threshold for assuming that population levels are sufficiently large for delisting the species.
Initial reports suggest, "breeding-age females are dying in higher than usual numbers from multiple causes, including infectious disease, toxin-exposure, heart failure, malnutrition and shark attacks".
No hypotheses were offered to suggest whether these findings were man-made, pollution related events or part of the natural life cycle of sea otter populations due to natural variability in ocean circumstances.
It could be, for example, that a combination of human and natural causes are depleting their food sources such as anemones and crabs, thus causing stress on the population. Once the food sources recover, so too will the Sea Otters.
Experts at The Monterey Bay Aquarium’s Sea Otter Research and Conservation program hypothesize that "Pathogens and parasites, possibly linked to coastal pollution, can weaken otter immune systems".
Sea otter population levels may be a function of both types of explanations.
In any event, the good news for sea otters is that the doubling of the population since the surveys began in the 1980s provides hope that the remaining population might have a stronger base to reach the magic 3,090 level. To date, that level has never been reached.
© 2011. Patricia A. Michaels. All Rights Reserved.