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__USGS Western Ecological Research Center
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The California Sea Otter Stranding Network is part of the USGS effort to monitor southern sea otters (Enhydra lutris nereis) and provide data to the U.S. Fish and Wildlife Service. WERC's Brian Hatfield and Dr. Tim Tinker works with multiple institutions and partners to report, recover, and examine stranded sea otters. TRENDS IN SEA OTTER MORTALITY Since 1968, biologists and veterinarians at the California Department of Fish and Wildlife (CDFW) and the USGS Western Ecological Research Center have documented and examined all reported sea otter strandings -- counting the number of dead, sick or injured sea otters recovered along California each year -- in an effort to understand the population trends of the southern...
The data are .csv files of tagged sea otter re-sighting locations (henceforth, resights) collected in the field using a combination of VHF radio telemetry and direct observation using high powered (80x) telescopes. Sea otters were tracked by shore based observers from the date of tagging until the time of radio battery failure or the animal’s death, whichever comes first. The frequency of re-sighting was opportunistic, depending on logistical factors such as coastal access, but generally ranged from daily to weekly. Location coordinates are reported as X and Y coordinates in the projection/datum California Teale-Albers NAD 1927. Each file contains resight data for one individual sea otter collected over a period...
A standardized method to survey sea otters (Enhydra lutris nereis) was developed by WERC scientists and put into use in 1982 in California. Survey procedures involve counting animals during the "spring survey" -- generally beginning in April and ending in June or early July, depending on weather conditions. Two-person teams use binoculars and spotting scopes to count individuals from accessible stretches of coastline and from fixed-wing aircraft in the remaining areas. The counts made from shore are plotted on maps and then entered into a spatial database. The aerial counts are entered directly into a geographic information system-linked database in the aircraft. The survey records the total otter numbers, the...

    map background search result map search result map Geospatial data collected from tagged sea otters in central California, 1998-2012 Geospatial data collected from tagged sea otters in central California, 1998-2012