September 26 through October 2 marks the annual Sea Otter Awareness Week. Defenders of Wildlife created this campaign in 2003 to promote awareness of sea otter conservation efforts and research. In this spirit, I’d like to take a moment to write a bit about the latest southern sea otter population estimates.
Each spring and fall, the US Geological Surveys conducts a census of southern sea otters, which range along California’s central coast from Año Nuevo in the north to Point Conception in the south. To get a feel for what the “otter spotters” are up against in their efforts, try to count the otters rolling around in the bull kelp in this photo.
Unfortunately, the 2010 Spring data create some cause for concern. This year’s population estimate is 2,711 individuals. This is a 3.6% decline from the 2009 estimate and a 4% decline from 2008. Before 2008, there had been a trend of slow population increase over the past decade. In addition to the recent declines in total population, only 267 pups were counted in the census this year. This is the lowest number of pups counted since 2003. The declines are most likely due to high mortality rates, especially among reproductive females.
As discouraging as this all sounds, it remains to be seen whether these findings are the beginning of a lasting downward trend or simply mild variation in what we hope will continue to be lasting population growth. As you can see from the graph below, a peak occurred in the mid-nineties that was surpassed by growth after the year 2000.
If you’d like more information about the census data, read the USGS press release and visit the USGS page for Sea Otter Studies. There are events for Sea Otter Awareness week scheduled throughout California and elsewhere; for a full list visit Defenders of Wildlife.