Every month we get an update of how many otters were found dead on beaches throughout the range. Sea otter strandings are one of several indices of how well the population is doing. It’s hard to tell from any one factor, and strandings can be especially unclear because so many factors go into whether or not a dead otter gets counted. Still, the numbers are useful in helping to identify unusual mortality events, long term populations trends, and seasonal fluctuations.
This October, we tied the previously held record high from 2003, with 36 stranded otters. Ten of these were found within the Cayucos-Hazard Canyon range of the coast, which includes the majority of Estero Bay.
In spite of this leap in October, overall the stranding count for the year is lower than usual. Of course this too could mean several things. Are less sea otters dying? That would be great! Or, given the recent decline in the count, we could surmise that there are less sea otters around to die. Lastly, because we must rely on the washed up sea otters we happen to find to give us a sense for what’s happening, we mustn’t overlook the fact that not all dead otters are found–they may sink, or wash up in remote areas where they aren’t counted. This could skew the data in either direction.
Assessing otter populations is complicated, as evidenced above! We want to respond to current trends, but sometimes it can be hard to spot those trends, let alone figure out what’s causing them. We’ll put out our annual status report in 2010 with our take on which way the otter population is really going.
Acknowledgement: The stranding summary is provided by the Sea Otter Stranding Network, a coalition that includes the Department of Fish and Game, USGS-Western Ecological Research Center, Monterey Bay Aquarium, California Academy of Sciences, and the Santa Barbara Museum of Natural History, amongst others.