Otters off SLO County tagged for reactions to seismic tests

Correction: Due to incorrect information supplied by the U.S. Geological Survey, an earlier version of this story incorrectly stated that the federal Fish and Wildlife Service has issued a permit allowing limited harassment of otters. PG&E has applied for such authorization, but the permit has not yet been given, said Scott Flaherty, USFW spokesman.

Wildlife biologists and other researchers from along the West Coast are in San Luis Obispo County this month to capture and tag as many as 60 sea otters as a way to measure their response to high-energy seismic studies scheduled to begin next month.

The research consists of surgically implanting into each otter a device that records its diving activity as well as a radio transmitter that allows researchers to track its movements for up to three years. Blood and tissue samples are also taken.

Of the 60 otters captured, 40 will be those living in the area where PG&E will conduct its offshore earthquake fault mapping, and 20 will be from outside that area. By comparing data collected from animals inside and outside the survey area, biologists will be able to measure how the otters react to the loud sounds emitted by the research vessel conducting the surveys.

“Sea otters spend more time on the surface of the water and have less sensitive hearing,” states a fact sheet about the monitoring project. “Thus, impacts of the project on sea otters could be less than the impacts on other marine mammals.”

The capturing and tagging operations are scheduled through Saturday in an area from Port San Luis to San Simeon. Shore-based teams of veterinarians using mobile surgical suites operated at locations north and south of Diablo Canyon nuclear power plant on PG&E land and in Morro Bay Harbor. On Thursday, they moved to San Simeon to finish the captures.

Aerial and shoreline monitoring of the otters will be conducted during and after the surveys to determine whether the animals’ behavior changes as a result of the surveys and to detect any dead or stranded animals.

During the first week of the project, 20 otters were captured and 16 were tagged. Four were pregnant females that could not undergo surgical implantation of the transmitters, said Tim Tinker, research leader with the U.S. Geological Survey.

“All surgical procedures and sampling has been successful and unremarkable, and all animals were returned to their capture sites alert and in good condition,” he said. “Field tracking of the radio-tagged study animals has also been progressing well, with all 11 of the animals tagged in days one and two of captures already resighted at least once.”

California sea otters are listed as threatened on the Endangered Species Act. PG&E has applied for a permit from the U.S. Fish and Wildlife Service that allows limited harassment of otters.

The otters are captured while sleeping by divers using long-handled nets called Wilson traps. In addition to implanting the two devices, a variety of measurements and samples are taken from the otters that allow veterinarians to assess the animals’ health and the type of stressors they are dealing with.

Time depth recorders are a valuable tool in tracking an otter’s feeding habits. The device records how deep the otter dives and how long it stays underwater.

“That gives us a good idea of how much energy they are expending each day, because when otters are diving they are hunting for food,” Tinker said. “The rest of the time, they are on the surface sleeping, grooming or nursing.”

The sea otter research project is a cooperative effort among the U.S. Geological Survey Western Ecological Research Center, U.S. Fish and Wildlife Service, California Department of Fish and Game and the Monterey Bay Aquarium. A USGS biologist from Alaska and veterinarians from Seattle Aquarium are also participating.

PG&E plans to begin its surveys in mid-November. The fault mapping is designed to yield new geologic information that was made more critical in light of the Fukushima disaster in Japan last year.