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sea otter population data

11/01/2021

Sea otters are crucial indicators of the health of our nearshore waters and coastal resources, from kelp forests to fisheries. These data, in conjunction with findings from several more in-depth studies provide the necessary information to assess female reproductive rates and changes in reproductive success of the California sea otter population through time. Following the end of the commercial harvest, sea otter populations gradually increased, although rates of recovery varied. These interactions will be discussed later, but include relationships with the great white shark, bald eagles, kelp, sea urchins, parasites and of course humans. The information gathered will be used by federal and state wildlife agencies in making decisions about the management of this sea mammal. 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). I utilized Landsat 5 high resolution multispectral imagery in order to examine 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. Because the sea otter only lives for around 10-20 years (Environment Canada, 2011), and is only able to produce one offspring every year, the population does not have the ability to grow quickly. Although this does not make sense in theory, as the current population of around 4,000 is far less than the carrying capacity (14,000), there is an explanation. The aerial counts are entered directly into a geographic information system-linked database in the aircraft. To achieve this, we will work with multiple collaborators to conduct a multi-disciplinary investigation of sea otter ecology, health and population biology. Sea otter research by scientists at the Santa Cruz Field Station of the USGS Western Ecological Research Center (WERC) focuses on this smallest marine mammal’s population biology and its role as a keystone species in the nearshore marine community. A standardized method to survey sea otters was developed by WERC scientists and put into use in 1982 in California. The 1914 data point is uncertain al- though the population was very small at that time. The population declined to a uniformly low density in the archipelago, suggesting a common and geographically widespread cause. For these reasons, this is only an estimation, and should be used solely as a rough estimate of future populations in the British Columbia area. 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. Other than special interactions, there are other factors that limit the sea otters population. In 1911, the global sea otter population dropped as low as 2,000 individuals, and the International Fur Seal Treaty was signed by Japan, Russia, the United States and the United Kingdom (for Canada). 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. Sea otters in Prince William Sound were from the original surviving 1911 population. 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. Population Historically, sea otters numbered between 150,000 and 300,000 animals throughout the Pacific Rim. Sea otters once ranged from Northern Japan to central Baja California, and had an estimated global population of between 150,000 and 300,000. “But now, thanks to legislative protection and a change of heart toward these furriest of sea creatures, the otter population has rebounded to steady levels in the Monterey Bay, and with 3,000 total in central California.” Hurray! WERC scientists conduct annual population surveys of the southern sea otter, a federally listed threatened species. Based on modeling studies using carcass, search effort, and population data, the total number of marine birds killed by the spill was between 300,000 and 645,000 birds, with the … Yet despite an overall increase in sea otter abundance, sharks have been “taking a bite” out of the portion of the population that could fuel expansion into new areas. By 1740, when the Bering expedition explored the coasts of the Aleutian and Commander Islands, there were between 100,000 and 300,000 sea otters on the Pacific coast. As the population expanded, they mostly increased in numbers in their current habitat rather than expanding to reclaim lost territory. However hunting which began the downfall of the sea otter in the Northern Pacific Ocean. The surveys, conducted cooperatively by scientists of the U.S. Geological Survey, California Department of Fish and Wildlife, U.S. 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. Sea otter data. For this reason, it is more difficult for the sea otter population to expand to other geographical locations. This relocation project was initially unsuccessful, as the population dropped to 28 individuals when the otters were first introduced. Population Trend (-10 to 10) 2 Distribution Trend (-10 to 10) By the early 20th century, northern sea otters were nearly extirpated from Alaska as a result of overharvest (Muto et al. Early European explorers reported vast numbers of sea otters (Enhydra lutris) in coastal waters of the Aleutian archipelago and mainland Alaska (Bancroft 1959; Lensink 1962). Aleutian sea otters have been in flux before. Currently the southern sea otter population is estimated at just above 3,000 animals. Click on the links below to explore other sea otter research projects conducted by WERC scientists and partners. 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. Monitoring efforts have varied in frequency and type across years. 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). Geographic Names Information System (GNIS), Mapping, Remote Sensing, and Geospatial Data, Western Ecological Research Center (WERC), Download Annual Survey Data from 1985 - present (ScienceBase), Population Biology and Behavior of Sea Otters, Annual Southern Sea Otter Survey: Despite Small Population Dip, Species Moves a Step Closer to Recovery, Sea Otter Survey Encouraging, but Comes Up Short of the “Perfect Story”, Numbers Encouraging, but Shark Bites Still Problematic for Sea Otter Recovery, Slowly Swimming Towards Recovery, California’s Sea Otter Numbers Holding Steady, Recovery Slows for California’s Sea Otters, 2012 Survey Shows, Weather Conditions Prevent California Sea Otter Annual Population Survey, California Sea Otters: Population Recovery Continues at Slower Rate. 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). 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. Southern sea otters, also called California sea otters, live in waters along the California coastline, ranging from San Mateo County in the north to Santa Barbara County in the south. Next, the population began to increase rapidly, in a section of the log curve known as the log phase. Fish and Wildlife Service and Monterey Bay Aquarium with the help of experienced volunteers, cover about 375 miles of California coast, from Half Moon Bay south to Santa Barbara. What are the consequences of the rapid sea otter decline in the Aleutian Islands? Data Series 1018 California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2016. At the present rate of decline, the population will reach the SSORT's recommended criterion for up-listing to Endangered within two to three years. This represents a translocated population. However hunting which began the downfall of the sea otter in the Northern Pacific Ocean. The 2013 surveys indicated that the sea otter population at heavily-oiled northern Knight Island, where abundance was depressed for two decades after the Spill, had finally reached pre-Spill levels. WERC scientists conducting long-term research in California and Alaska seek to answer complex ecological questions. Fur traders in the 18th and 19th centuries hunted the animals to the brink of extinction, allowing sea urchin numbers to skyrocket, Dr. Rasher said. However in 1969, Canada undertook a reintroduction program which relocated 89 sea otters from Alaska to the coastal waters of British Columbia. 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. 2. However, the overall sea otter population size in southwest Alaska has Sea otters once ranged from Northern Japan to central Baja California, and had an estimated global population of between 150,000 and 300,000. One is the relatively small home ranges of sea otters. New otter pups need mom’s attention for about six to eight months, 24/7. However the actual rate of growth has slowed to around 8% each year from 1995 to 2004 (Environment Canada, 2014). Fish and Wildlife Service (FWS) listed the southern sea otter population as threatened under the Endangered Species Act (ESA) in 1977 and adopted a recovery plan for the population 1982, which was updated in 2003. The spring 2019 mainland sea otter count began on May 1 and was completed by July 9. Main Characteristics Of The Sea Otters Anatomy. 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. Several factors historically restricted gene flow within the sea otter popula-tion. WERC's sea otter team and U.S. and Canadian researchers have teamed together to investigate. Figure I. Abundance of California sea otter population from 1911 through 1999. Despite this, there are still many similarities between the logistic growth curve, and the growth patterns of the British Columbian sea otters. Fish and Wildlife Service. Data Series 1097 California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2018. Why is California’s threatened sea otter population growing so slowly? considered in these analyses. For southern sea otters to be considered for removal from threatened species listing, the population index would have to exceed 3,090 for three consecutive years, according to the threshold established under the Southern Sea Otter Recovery Plan by the U.S. to make generalizations about the plight of the California sea otter population as a whole, the data provides strong evidence that when humans are in too close proximity to otters, they alter their behavior signiÞcantly. Sea otters have inhabited the northern coasts of the Pacific Ocean since the Pleistocene, about 1 to 3 million years ago. By the mid 1800’s, the sea otter was considered to be on the brink of extinction. Following re-introduction, the British Columbia Sea Otter population grew rapidly (18.6% per year) from 1977 to 1995 on Vancouver Island. Then in 1914 a remnant population of about 50 southern sea otters was found along the rugged Big Sur shoreline. This year’s overall count of 3,186 exceeded the 3,090 threshold set by the FWS. One controversial hypothesis is that orcas have been eating the otters. Bbox East Long-120.226095 Bbox North Lat: 36.599 Bbox South Lat: 34.4157 Bbox West Long WERC's sea otter researchers are developing and utilizing a variety of methodological and analytical tools to understand the causes of biological and ecological trends in sea otter populations, and to predict the ecological consequences of management practices on these populations and their ecosystems. SANTA CRUZ, Calif. — The southern sea otter population continues its pattern of tepid recovery, according to the latest population survey led by U.S. Geological Survey, California Department of Fish and Game Office of Spill Prevention and Response and Monterey Bay Aquarium scientists. Counts of otters were Researchers surveyed sea otter populations along the mainland coast, from Pigeon Point in the north to Gaviota State Park in the south, and also the distinct population at San Nicolas Island in the southern California Bight. This means that the predicted population 5 years in the future is really only for 2 years in the future (2013). Restoring the sea otter population in Alaska can help the region to revitalize the ecosystem and slow down reef erosion. When sea otters want to rest, they wrap a piece of kelp around their body to hold themselves steady among the rolling waves. 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). This population, established by introducing sea otters back into the area in the late 1980s, struggled at … ... Distribution of the Sea Otter (Enhydra lutris) Data based on Otters of the World (IOSF 2015) 2000a). The population decline likely began in the mid-1980s and declined at a rate of 17.5%/year in the 1990s. The sea otters have a flexible skeleton and their face is small and round. In a historic rebound, California sea otters, the frolicking ocean ambassadors of Monterey Bay and Big Sur, have reached their highest population level since 1982, when federal and state officials … 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. 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. Cover: ... survey of the sea otter population at San Nicolas Island was completed earlier in the spring (April 13–15) under fair-good survey viewing conditions (View Score = 1.5). In 1969, 89 otters were re-introduced to the British Columbian Coast Line (Province of British Columbia, 2003), which marked the beginning of a growth curve. The counts made from shore are plotted on maps and then entered into a spatial database. What clues does the sea otter's decline hold for our knowledge of ecosystem and global change? These data, in conjunction with findings from several more in-depth studies, also provide the necessary information to assess female reproductive rates and changes in reproductive success of the California sea otter population through time. Their measurements vary depending on the sex. Download annual survey data from 1985 to present. Population recovery of the southern sea otter has been slow (rate of population increase λ = 1.05) compared to other recovering populations (λ = 1.17–1.20), and the population declined (λ = 0.975) between 1995 and 1999. 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. How do sea otters impact near-shore marine food webs? 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. The sea otter population within the Monterey Bay National Marine Sanctuary is estimated to be more than 1,200. 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. It included an article which prohibited non-natives and anyone hunting for commercial purposes from hunting sea otters. the sea otter translocation program. (1) Sea Otter Single Moms. California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2019 By Brian B. Hatfield, Julie L. Yee, Michael C. Kenner, and Joseph A. Tomoleoni Abstract The 2019 census of southern sea otters (Enhydra lutris nereis), also known as California sea otters, was conducted from early May to early July along the mainland coast of Since the 1980s, U.S. Geological Survey scientists have calculated a population index each year for the southern sea otter (Enhydra lutris nereis), a species federally listed as threatened. In addition, the sea otter population size, density, and trajectory are all much greater in Alaska relative to California. With the decrease in the number of sea otters, there has been a steep rise in the population of sea urchins, the population of which was kept in check by otters. These data, in conjunction with findings from several more in-depth studies, also provide the necessary information to assess female reproductive rates and changes in reproductive success of the California sea otter population through time. The main limiting factor of the sea otter population is the result of interactions with other species, including humans. The spring 2019 mainland sea otter count began on May 1 and was completed by July 9. No single year's survey result is indicative of a population change, however. Remnant population. The logistic growth models assumes that the per capita growth rate declines as population size approaches a maximum. In general, the growth pattern exhibited by the sea otter population is logistic growth (Carter-Edwards, 2011). A hierarchical modeling framework was used that allows for the incorporation of data from multiple sources collected at different spatial scales. From 1977-1995, the population showed steady growth and averaged 19.1% growth over this time period (Nichol, 2002). In fact, when the sea otter population was initially introduced, it experienced negative growth. Recent population surveys (2008) indicate the Canadian Sea Otter population includes a minimum of 4,110 animals along the west coast of Vancouver Island and 602 animals on the central British Columbia coast. For 2014, USGS reports the population index as 2,944 (data available online). Monitoring efforts have varied in frequency and type across years. 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. Below are news stories associated with this project. 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. 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- … Browse the menu, click on the "Data and tools" tab, "News" tab, and "Related" tab to learn about sea otter biology and the annual California sea otter population survey. This population, established by introducing sea otters back into the area in the late 1980s, struggled at … This includes predators, prey, and competition from other species, parasitic infection and changes in environment due to human interaction (Environment Canada, 2011). California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2019 By Brian B. Hatfield, Julie L. Yee, Michael C. Kenner, and Joseph A. Tomoleoni Abstract The 2019 census of southern sea otters (Enhydra lutris nereis), also known as California sea otters, was conducted from early May to early July along the mainland coast of 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). Surveys of sea otters in the 1970s and 1980s indicated a healthy and expanding population in most of Alaska, including Prince William Sound. I utilized Landsat 5 high resolution multispectral imagery in order to examine As of 2010, the Washington sea otter population totals just over 1,000 otters. For example the sea otter has a very low biotic potential.

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