Historically, sea otters occurred in coastal waters throughout the rim of the North Pacific Ocean from northern Japan to Baja California, Mexico, with southern sea otters ranging from Oregon to Baja California. In 2017, the U.S. Navy and the U.S. Tinker, M. T., Doak, D. F., Estes, J. doi: 10.1016/B978-0-12-801402-8.00006-8, Monson, D. H., and DeGange, A. R. (1995). The conservation of sea otters: a prelude, in Sea Otter Conservation, eds S. E. Larson, J. L. Bodkin, and G. R. VanBlaricom (London: Elsevier Academic Press), 117. The earliest censuses of sea otters were conducted by the Russian Coast Guard in the Commander Islands from 1924 to 1930 (Barabash-Nikiforov, 1947). How could you test your hypothesis from question 4? doi: 10.1016/B978-0-12-456160-1.50010-2. As sea otter populations continue to expand in their range and numbers, monitoring will become increasingly challenging, likely resulting in reduced effort and statistical power to detect change (Williams et al., 2018). Figures of Pages from the Monitoring and Research Plan for Southern Sea Otter Military Readiness Area. For example, management could focus on protecting habitats that provide refugia from predation by killer whales and sharks. Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades. Part or all of this report is presented in Portable Document Format Many of these challenges will require new tools including the next generation geolocation tag technology that will allow assessments of long-range movements, dispersal and gene flow in various populations. In addition to their fishery-related impacts, sea otters may come into conflict with recovery efforts for other threatened or endangered species that are part of their natural prey base. After their near extirpation, remnant sea otter populations and those that resulted from reintroduction were below carrying capacity and experienced a period of logistic growth. Trends in Sea Otter Population Abundance in Western Prince William Sound, Alaska: Progress Toward Recovery Following the 1989 Exxon Valdez Oil Spill . What is the trend between 15-30 years in the sea otter population? Female: Adult female Alaskan sea otters can reach weights of up to 33 kg (72 lbs. Central California gill net effort and bycatch of sensitive species, 1990-1998, in Seabird Bycatch: Trends, Roadblocks, and Solutions, eds E. F. Melvin and J. K. Parrish (Fairbanks, AK: University of Alaska Sea Grant), 141160. Sea otters have forepaws, which can rub, twist, and pull. Since its discovery along the coast of central California, the southern sea otter population has grown at anemic rates compared to populations in Alaska. In 1969 and 1970, a total of 59 sea otters were captured at Amchitka Island, Alaska, and released near Point Grenville and LaPush off Washington's Olympic Peninsula coast (Jameson et al. What is the general trend in the kelp population that is seen between 0-20 years? History and status of sea otters, Enhydra lutris along the coast of Hokkaido, Japan. Sea otters were hunted extensively for both food and their fur. We often define populations by genetic structure as measured by the genetic similarity/dissimilarity of various subpopulations, which itself is a product of demographic processes. For San Nicolas Island (right vertical axis, note scale difference) the trend line (lowest line, in red) represents the annual high counts. Annually, we estimated abundance for all species within four regions spread across 1,000 km in the Gulf of Alaska. Sea otters likely have been the top-down force structuring clam populations along the KATM coast as clams constitute 63% of the otters diet. The population declined to a uniformly low density in the archipelago, suggesting a common and geographically widespread cause. <> A. doi: 10.1016/B978-0-12-801402-8.00013-5, Pennock, D. S., and Dimmick, W. W. (1997). Trends Ecol. These aquatic members of the weasel family are often seen floating on their backs. USGS California Sea Otter Surveys and Research page, International Union for Conservation of Nature (IUCN) Sea Otter page, Marine Mammal Commission Sea Otter Reintroduction Fact Sheet, Marine Mammal Commission: An Independent Agency of the U.S. Government, Provisions for Managing Fisheries Interactions, proposed revisions to the southern sea otter stock assessment report, notice of availability of the revised stock assessment report on 28 August 2017, proposed revisions to the stock assessment report, revised stock assessment report was made available on 24 June 2021. The threat to the southern sea otter posed by oil spills prompted . Here, we give examples of the challenges in defining sea otter populations and the consequences of managing populations at an inappropriate scale. Click the Edit button above to get started. Intraperitoneal radio transmitters have been used to track sea otters (Garshelis and Siniff, 1983). (2008). Chads et al. Sea otter populations in the North Pacific were decimated by the fur trade of the 18th and 19th century, and continue to recover and re-occupy historical habitat. (2013). The monitoring program, at its basic level, includes quarterly seasonal surveys of population abundance, distribution, and foraging activity. Restoration of kelp forests in the nearshore increases biodiversity by moving the ecosystem from one dominated by sea urchin barrens to one characterized by a wide variety of kelp-dependent species of invertebrates, fishes and seabirds (Estes, 2015). Over the past 45 years, the sea otter population has experienced a 50% decline. The population has grown by about 10 percent per year over the past decade and contained about 100 otters in 2019. Although this framework has been applied to sea otters (Loomis, 2006; Richardson and Loomis, 2009), further development and implementation is needed. Documented effects of sea otter reoccupation on marine communities include: (1) the expansion of kelp forests by reducing sea urchin populations (Estes and Palmisano, 1974; Estes and Duggins, 1995; Watson and Estes, 2011); (2) the creation of habitat for kelp settlement through disturbance (Kvitek et al., 1992; Weitzman, 2013; Traiger et al., 2016), (3) changes to epifaunal and infaunal species densities and size distributions (Singh et al., 2013; Weitzman, 2013) and (4) a reduction in commercially valuable invertebrates (Estes and VanBlaricom, 1985; Wendell et al., 1986b; Wendell, 1994; Watson and Smith, 1996; Larson et al., 2013; Hoyt, 2015). For sea otters, dispersal distance is one of the least studied aspects of their biology, and developing new technologies to study dispersal should be a high priority for future research. Wendell, F. E., Hardy, R. A., Ames, J. Their food is usually filter feeders Why go to all the effort to save sea otters? +(> Xi~PHa3sX#s-mCR*1rFY$Vz!`:_OV Historic and contemporary status of sea otters in the North Pacific, in Sea Otter Conservation, eds S. E. Larson, J. L. Bodkin, and G. R. VanBlaricom (London: Elsevier), 4361. Consequently, the frequency of large scale surveys in areas such as Southeast Alaska and the Aleutian Islands declined to decadal intervals. Current (purple) and historic (yellow) sea otter range. Fish and Wildlife Service (FWS) listed the Southwest Alaska stock as threatened in 2005 and designated critical habitat for the population in 2009. Census counts may be made from shore, the water or the air. Continued protection and conservation will be required for many decades. B., Staedler, M. M., and Bodkin, J. L. (2006). Fortunately, sea otters have an appetite for sea urchins and they help to keep sea urchins in check, allowing the kelp to flourish and capture CO 2. doi: 10.3354/esr00327, Hattori, K., Kawabe, I., Mizuno, A. W., and Ohtaishi, N. (2005). The FWS published anotice of availability of the revised stock assessment report on 28 August 2017, in which it addressed the comments submitted by the Commission and others. The most recent estimate of sea otter population abundance in Washington was 2,785 individuals (2,632 independents, 153 pups; Jeffries et al. (2015). Sea otters rely on their fur for insulation, which cannot be compromised by the attachment of external satellite telemeters used with many other marine mammal species. (USGS). Sea otters are one of the few mammal species that are known to use tools like rocks to hunt and eat food. Share sensitive information only on official, secure websites. As further range expansion continued, the proportion of the population surveyed by shore and air continued to change, with less survey effort from shore, where detection probability is high, to more survey effort from the air, where detection probability is lower, with potential implications for the interpretation of population trends. Session 6: Sea otter conservation, volume 2 Moderator: Jim Bodkin 10:40am Food and energy intake of managed sea otters David Rosen 10:50am The history of monitoring sea otter recovery and conservation George Esslinger 11am Sea otters, seagrass and saltmarshes: past and present Erin Foster 11:10am What drives sea otter population growth and . 2), (2) the extent to which current density varies among locations, . Express the amount as a multiple of the imported population and as a percentage. Zool. Barabash-Nikiforov, I. I. Historically, sea otters numbered in the hundreds of thousands in the North Pacific Ocean, but due to the fur trade, their numbers plummeted in the early 1900s. <> Resource Competition, Space Use and Forage Ecology of Sea Otters, Enhydra lutris, in Southern Southeast Alaska. 2 0 obj Killer whale predation on sea otters linking oceanic and nearshore ecosystems. Kreuder, C., Miller, M. A., Jessup, D. A., Lowenstine, L. J., Harris, M. D., Ames, J. (2009). What is causing the rapid loss of sea otters in Alaska? Why do you find those questions interesting? Mar. (2009). Fish. J. Exp. doi: 10.2307/3672835, Reidy, R. D., and Cox, S. P. (2013). J. Exp. Small numbers of lobsters (26), octopus (16), and abalone (5) also were identified. Gorbics, C. S., and Bodkin, J. L. (2001). Similar serial harvests are not likely to be repeated, but any management strategy that allows harvests of any kind should consider harvest levels within smaller geographic subunits. 32, 309326. Med. Calif. Markel, R. W. (2011). doi: 10.1371/journal.pntd.0002852, Watson, J., and Estes, J. Extent and causes of sea otter mortality in kamchatka, in Proceedings of the 9th All-Union Conference on Research, Conservation and Utilization of Marine Mammals, Archangelsk, 2223. *Correspondence: Randall W. Davis, davisr@tamug.edu, Future Directions in Research on Marine Megafauna, View all Today, southern sea otters occupy approximately 13% of their historic range; their current distribution extends along the central California coast from Monterey Bay to Point Conception. /CA 1.0 24, 115. doi: 10.1890/08-0765.1, Williams, P. J., Hooten, M. B., Womble, J. N., Esslinger, G. G., and Bower, M. R. (2018). Dean, T. A., Bodkin, J. L., and Coletti, H. A. Because the proportion of mussels in sea otters diet at KEFJ was correlated with large mussel abundance, reduced mussel abundance could have a significant effect on sea otter carrying capacity where they are important prey. Am. Measures of effective population size in sea otters reveal special considerations for wide-ranging species. From 1965 to 1990, seven sea otter translocations were made into historically occupied habitat, resulting in five self-sustaining populations. With increased sea otter foraging effort, GWA has observed a decline in available clam biomass further supporting food limitation as the driver in the sea otter population status. Management applications include possible translocations around shark barriers in California to restart population expansion and among hotspots in the western Aleutian Islands to maintain gene flow and genetic health. collected in 2010-2012, for sea otters in Southeast Alaska. Southern sea otter population density along the California coast. They spend around 40% of their time hunting and eating and eat about 25% of their body weight every day. A member of the weasel family, the sea otter ( Enhydra lutris) keeps warm in the water because it possesses the densest fur in the animal kingdom - about 850,000 to a million hairs per square . Sea otters are born swimmers with long, sleek, streamlined bodies with webbed feet. ) or https:// means youve safely connected to the .gov website. MATERIAL AND METHODS Sea otter population changes. Clim. During the past 60 years, much has been learned about their natural history, physiological adaptations for an aquatic life, and the important role they play in structuring nearshore marine ecosystems. doi: 10.1016/j.ijpara.2003.12.008, Monson, D., Estes, J. Ecology 85, 33733384. Ecol. A second method to monitor abundance is to correct for sighting bias of animals not detected and areas not surveyed. Fish and Wildlife Service (2013). Abalone mariculture occurs beneath the Monterey wharf in California in protective cages and indirectly benefits from the presence of sea otters through enhanced local availability of giant kelp, which is harvested to feed the growing abalone. J. Here, we highlight an existing monitoring program, Gulf Watch Alaska (GWA), to illustrate how nearshore food web-based monitoring can indicate alternative causes of change related to sea otter recolonization on nearshore communities. 4 0 obj Sydney Institute of Marine Science, Faculty of Science, University of New South Wales, Australia, San Francisco Bay Bird Observatory, United States. /ColorSpace /DeviceRGB Change 3, 913918. Mamm. See how sea otters maintain the balance of kelp-forest ecosystems by consuming sea urchins They are a keystone species, so if they die, so will much of their habitat. In British Columbia and Southeast Alaska, conflicts did not begin to emerge for several more decades because sea otters were not reintroduced to these areas until the late 1960s and early 1970s (Bigg and MacAskie, 1978; Jameson et al., 1982; Nichol, 2015). 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. Examples of this type of strategy include conducting smaller spatial-scale surveys at more frequent intervals (Bodkin, 2015; Coletti et al., 2016), rather than large-scale surveys less frequently, where demographically distinct population trends could become confounding (Esslinger and Bodkin, 2009). A., and Duggins, D.O. Sea otters and kelp forests in Alaska generality and variation in a community ecological paradigm. Sea otters may homogenize mussel-beds and reduce habitat provisioning in a rocky intertidal ecosystem. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). Foraging effort (i.e., number of hours per day spent feeding) appears to be related to the status of the population relative to food availability across nearly all the sea otters current range (Estes et al., 1986; Bodkin et al., 2007; Monson and Bowen, 2015; Coletti et al., 2016; Cortez et al., 2016). 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. A., Kreuder, C., Paradies, D. M., Worcester, K. R., Jessup, D. A., et al. Stock structure of sea otters (Enhydra lutris kenyoni) in Alaska. The geographic range of sea otters has fluctuated over the last 300 years. Sea otter distribution in California (the mainland range) is . A. 70, 14981507. This research project has direct relevance for the Wildlife program of the Ecosystems Mission Area (ECO), which works with others to provide the scientific understanding and technologies needed to support the sound management and conservation of our Nation's biological resources. Sci. 6) The data collected by Dr. Estes are shown. doi: 10.1111/j.1748-7692.2007.00167.x, Wolt, R. C., Gelwick, F. P., Weltz, F., and Davis, R. W. (2012). PDF documents opened from your 10, 100107. Fish and Wildlife Service, 2013). NEW! doi: 10.1126/science.185.4156.1058, Estes, J. Data suggest that mussel bed dynamics may be driven by processes that influence whether or not individuals survive to sizes suitable as sea otter prey, rather than that mussels are driven exclusively by top-down effects of sea otter predation (Coletti et al., 2016). (Public domain.) doi: 10.2174/1874401X01306010028, Richardson, L., and Loomis, J. Despite the translocation having been declared a failure, the population on San Nicolas Island continues to increase. From 2017 to 2020, we measured a 22-percent per annum increase in population abundance (95-percent confidence interval =1134 percent) with 114 total individuals as of February 2020. The first efforts to restore sea otters to parts of their historical range took place from the mid-1960s to the early 1970s in a series of translocations from Amchitka Island and Prince William Sound to the Pribilof Islands in Alaska, Southeast Alaska, Vancouver Island in British Columbia, and Washington and Oregon states (Jameson et al., 1982). These complementary sources of carbon provide some resilience to species of suspension feeding invertebrates that depend on particulate organic carbon (POC). Research indicates that sea otters and commercial bivalve fisheries in Southeast Alaska are generally incompatible (Larson et al., 2013; Hoyt, 2015). Killer appetites: Assessing the role of predators in ecological communities. A., Chan, F., Nielsen, K. J., Lorenzo, E. D., and Lubchenco, J. 75, 978989. Sea Otters (Enhydra lutris) and Steller Sea Lions (Eumetopias jubatus) in the North Pacific: Evaluating Mortality Patterns and Assessing Population Status at Multiple Time Scales. Sign Me Up. Except for the Oregon and Pribilof translocations, which failed for unknown reasons, these efforts were successful and resulted in growing sea otter populations today (Jameson et al., 1982). This example provides direction for future research and monitoring to address management goals. 13, 219229. 30 mil 20 mil 6 mil 0 5 10 15 20 25 30 Years. Initially, remnant populations were small and occupied small ranges, enabling surveys that could be conducted from skiffs with limited personnel and time. endobj .0.50 0 20 40 60 80 100 Time, days A-55793 . Mar. At the same time, sea otters have helped to restore the ecological functioning of degraded coastal ecosystems by initiating trophic cascades in kelp forests (Estes and Palmisano, 1974; Estes and Duggins, 1995; Watson and Estes, 2011) and estuaries (Hughes et al., 2013), thereby providing valuable ecosystem services by means of these indirect effects. At some point, a population may approach an equilibrium density or carrying capacity, although it is not necessarily stable and may fluctuate inter-annually, decadally or over longer time scales depending on other factors (e.g., disease, predation). (2007). As the population expanded both north and south into habitat that was not observable from shore, aircraft were used for surveys. From a conservation genetics perspective, it is interesting to note that genetic diversity is highest in translocated populations derived from two source populations (Larson et al., 2002b). The U.S. the mean tree leaf area per plot that the scientists recorded after running the experiment for 18 months 2,000 cm^2 are the control plots and 1,100 cm^2 for the plots of the beetles Compare the trends in mean tree leaf area per plot for both the plots with the beetles added and the control plots over the 18 months of the experiment The first is considered a census, where it is assumed that all animals in an area are counted, and precision is not usually estimated. ZM' NXd$t S4jBc 35*([3mS?AT?23n VTFloB'@{#"Q#9tf(;l&~Y]r]BRILI=RaqoFHlVq3_b#=:#$Cqh5Ig!HHX@7;f(ZAM":kbSv()452.%XbCMb0~M{*!*={YQG0p You will, 1 out of 1 people found this document helpful, Name: _________________________________________________________, the four graphs located on the last two pages of this document. 560, 7386. Fort Collins, CO: National Park Service. Bull. A., van Vliet, G. B., Williams, T. M., Doak, D. F., Danner, E. M., et al. Foraging behavior and prey of sea otters in a soft- and mixed-sediment benthos in Alaska. Diseases (Toxoplasma gondii in California and Streptococcus Syndrome in parts of Alaska) also may have a density-dependent effect on local populations (Johnson et al., 2009; Mazzillo et al., 2013; Van Wormer et al., 2014; Counihan et al., 2015; Bartlett et al., 2016). Salomon, A. K., Kiiiljuus Barb, J. W., White, X. E., Tanape, N., and Happynook, T. M. (2015). doi: 10.1139/z84-385. Mother sea otters nurse their pup for about eight months. Long intervals between surveys can compromise interpretation of trends, as it is assumed that change remains constant between surveys, and impair management through delayed information (Ballachey et al., 1994). /Width 500 In 2020, the Commission commented on more proposed revisions to the stock assessment report. /ca 1.0 Microsatellite DNA and MtDNA variation in remnant and translocated sea otter (Enhydra lutris) populations. Look for historical information that might make your narrative more interesting. Otters eat urchins, and urchins eat kelp. Historical ecology of late Holocene sea otters (Enhydra lutris) from northern British Columbia: isotopic and zooarchaeological perspectives. Fish and Wildlife Service (FWS) listed the southern sea otter population as threatened under theEndangered Species Act (ESA)in 1977 and adopted a recovery plan for the population in 1982, which was updated in 2003. /Title () of food each day. 52, 7076. 21, 169172. Adult male California sea otters average 29 kg in mass, while females average 20 kg. So using a variety of established study methods radio tracking, veterinary exams, genetic analysis, diet observations this collaborative group of scientists hopes to uncover new knowledge about this population of Californias iconic sea otters a population that hasnt been extensively studied for 15 years. In Alaska, some lawmakers in the state government have suggested that sea otters be culled to reduce pressure on certain commercially exploited invertebrates, but this would require a change in the Marine Mammal Protection Act of 1972. Ecol. Sea otters regularly dig for infaunal prey (e.g., bivalves) in eelgrass meadows (), inadvertently breaking up rhizomes, creating pits (), and leaving bare patches where seeds may settle (Fig. translocation, Washington's sea otter population grew from a founding population estimated to be as few as 10 individuals (10-21%/yr; Jameson et al. , Bodkin, J. L. ( 2006 ) Columbia: isotopic and zooarchaeological perspectives numbers of (. Mammal species that are known to use tools like rocks to hunt and eat about 25 % their! In ecological communities experienced a 50 % decline Prince William Sound, Alaska: Progress Toward Recovery the., the sea otter distribution in California ( the mainland range ) is every.! 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