The southern sea otter (Enhydra lutris nereis) population at San Nicolas Island, California, has been monitored annually since the translocation of 140 sea otters to the island was completed in 1990. counts of sea otters during 1990-96 at oiled sites were as high or higher than boat-based counts in the same area in the early 1980s. In general, the current otter population is stable, however its troubled past and vulnerability to oil spills result in the need to protect the species (Fisheries and Oceans Canada, 2013). Home DATA THREATS The world-wide sea otter population was drastically reduced to just a few hundred animals between 1742-1911, due to commercial harvest by the Russian and Russian/American fur trades Between 1992-2000, there was a decline of about 70% in this population. I utilized Landsat 5 high resolution multispectral imagery in order to examine Overall viewing conditions this year were very good, better than those encountered during the 2018 spring census (View Score = 3.0 this year compared to 2.4 last year, where 0=poor, 1=fair, 2=good, 3=very good, and 4=excellent). U.S. Geological Survey scientists say the latest 3-year average (2,813 sea otters) was 0.5 percent lower than last year, the first time the trend has been negative since the late 1990s. This means that the predicted population 5 years in the future is really only for 2 years in the future (2013). As healthy kelp forest ecosystems are critical for sea otter survival, significant change or loss in kelp forest may have contributed to the unsuccessful recovery efforts of the translocated population. Then in 1914 a remnant population of about 50 southern sea otters was found along the rugged Big Sur shoreline. The southern sea otter was widely believed to be extinct due to the expansive fur trade of the 18th and 19th centuries, which reduced the global population from between 150,000 and 300,000 to roughly 2,000. Click here to learn more. Sea otters are crucial indicators of the health of our nearshore waters and coastal resources, from kelp forests to fisheries. The International Fur Seal Treaty protecte… The logistic growth models assumes that the per capita growth rate declines as population size approaches a maximum. Sea otter data. 2000a). In recent decades, the sea otter population the Aleutian Islands of western Alaska has plummeted. The minimal population estimate was 8,742 sea otters in 2000. This too happened in the sea otter population, as they experienced an average rate of change of over 19% per year from 1977 to 2004. 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. Currently, according to the log curve, and given the carrying capacity of the sea otter population, they should still be in the log phase of the curve. This includes predators, prey, and competition from other species, parasitic infection and changes in environment due to human interaction (Environment Canada, 2011). Sea otter habitat is considered to extend offshore from the mean low tide line and out to the 60m isobath: this depth range includes over 99% of sea otter feeding dives, based on dive-depth data from radio tagged sea otters (Tinker et al 2006, 2007). In this phase, a rapid increase in population can be attributed to an adequate population size, and an abundance of resources. source: J. L. Bodkin, R. J. Jameson, J. The sea otter population is thought to have once been 150,000 to 300,000, stretching in an arc across the North Pacific from northern Japan to the central Baja California Peninsula in Mexico. The aerial counts are entered directly into a geographic information system-linked database in the aircraft. When sea otters want to rest, they wrap a piece of kelp around their body to hold themselves steady among the rolling waves. What clues does the sea otter's decline hold for our knowledge of ecosystem and global change? In fact, when the sea otter population was initially introduced, it experienced negative growth. CALIFORNIA SEA OTTER POPULATION ANNUAL SURVEY – survey history and methodology. SANTA CRUZ, California — The southern sea otter, Enhydra lutris nereis, continues its climb toward recovery, according to the annual count released today by the U.S. Geological Survey and partners. This relocation project was initially unsuccessful, as the population dropped to 28 individuals when the otters were first introduced. To achieve this, we will work with multiple collaborators to conduct a multi-disciplinary investigation of sea otter ecology, health and population biology. Likewise, California’s sea otter numbers are holding steady against the many forces pushing against their population recovery, according to the latest field survey led by federal, state, aquarium, and university scientists. Their measurements vary depending on the sex. The estimated population size for the Southwest Alaska stock is slightly higher than in the previous stock assessment report due to the addition of Katmai, which was surveyed in 2009 for the first time. An estimate of otter population size in Alaska was 98,780 among the three populations in 2013 (USFWS, 2013) with observed annual growth rates in some areas reaching 16–20% (Bodkin et al., 1999; Estes, 1990). the sea otter translocation program. Firstly, when initially introduced to the new environment, the sea otters experienced repressed growth. About 1995, however, the population dynamics changed for unknown reasons and the population began to decline; annual population counts have steadily decreased since 1995 (USGS-BRD, unpublished data). Click on the links below to explore other sea otter research projects conducted by WERC scientists and partners. Researchers wishing to use the data are encouraged to contact the owners to acquire appropriate data permissions and also obtain additional meta-data for tagged sea otters. Initially, it was only the Native Americans who hunted the sea otter, however when Europeans came to North America and began the maritime fur trade, this amplified the problem (Nichol, 2002). However, this did not prevent the sea otter population from continuing to decline, and in 1929, the last verified sea otter in Canada was shot and killed (Nichol, 2002). The counts made from shore are plotted on maps and then entered into a spatial database. Restoring the sea otter population in Alaska can help the region to revitalize the ecosystem and slow down reef erosion. The southern sea otter of California, a threatened population on the Endangered Species list, continues to recover, but the rate of recovery appears to have slowed. In coordination with the California Department of Fish and Game and other institutions, ongoing surveys and research continues to inform the southern sea otter recovery plan for the U.S. Another study reported a significant decline in sea otter numbers after the spill, but our reanalysis of that data produced results very similar to ours. Population Historically, sea otters numbered between 150,000 and 300,000 animals throughout the Pacific Rim. There it is either approaching, or already at, carrying capacity (Gagne et al., 2018 ; Smith, Newsome, Estes, & Tinker, 2015 ). For example, the population used in this calculation is taken from 2008, which means that any prediction made, starts in 2008. In the following years, the otter population began to grow and prosper. Following re-introduction, the British Columbia Sea Otter population grew rapidly (18.6% per year) from 1977 to 1995 on Vancouver Island. Sea otters came under international protection in 1911 and since then, their numbers have rebounded. Likewise, California's sea otter numbers are holding steady despite many forces pushing against their population recovery, according to the latest field survey led by federal, state, and UC Santa Cruz scientists. If data obtained by the same methods at each site are used, sea otter population counts at Attu Island, south-east Alaska, British Columbia, and the State of Washington have increased at 17-20% year- … The sea otter (Enhydra lutris kenyoni, Wilson et al., 1991) population in Washington State was reintroduced to the outer coast in 1969–1970.By 2007 the population numbered at least 1,125 animals, having increased at an average rate of 8–10% per year since 1977 (Jameson 1998; Jameson et al. Aleutian sea otters have been in flux before. Within their core range in California, where sea otter population growth is largely limited by food availability, more than 63 percent of all strandings are strongly related to crowding. This year’s overall count of 3,186 exceeded the 3,090 threshold set by the FWS. Santa Cruz, Calif. – After a decade of steady recovery, the southern sea otter — a federally listed threatened species — is in decline for the second year in a row, according to the latest population survey by U.S. Geological Survey researchers. For many years, there were no sea otters in Canadian waters and most of the sea otters in the world were located in the Aleutian Islands, off of the coast of Alaska. Sea otters once ranged from Northern Japan to central Baja California, and had an estimated global population of between 150,000 and 300,000. As a result, the areas currently occupied by the sea otter have reached equilibrium densities, and as a result the growth has diminished. Monitoring efforts have varied in frequency and type across years. In addition to the sea otter population along the mainland California coast, USGS and partners also survey the sea otters at San Nicolas Island in the Southern California Bight. Figure I. Abundance of California sea otter population from 1911 through 1999. The survey records the total otter numbers, the number of dependent pups, and the number of independents (adults and subadults), observed. In the most recent study in 2008, the sea otter population in British Columbia had increased to about 4,700, up from 3,200 in 2004. Fish and Wildlife Service. The most striking example was the Exxon Valdez oil spill in Prince William Sound, Alaska in 1989, which spilled 11 tons of crude oil and killed approximately 3,905 sea otters (range 1,904-11,257). 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