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). A., Ricca, M. A., Miles, A. K., and Forsman, E. D. (2008). Sea otters do hold hands. doi: 10.1073/pnas.94.26.14530, Miller, M. A., Gardner, I. Johnson, C. K., Tinker, M. T., Estes, J. ELKHORN SLOUGH SEA OTTER RESEARCH - OF ESTUARIES AND SEA OTTERS. Given the contribution of translocations to the conservation of sea otters by increasing the total numbers of sea otters present today, increasing population connectivity, increasing genetic diversity, and restoring coastal marine ecosystems, we suggest additional translocations be considered to facilitate sea otters recolonization of their historical range. Current (purple) and historic (yellow) sea otter range. Furthermore, an abundance of urchins (a primary sea otter prey) in habitats where sea otters disappeared (Stewart et al., 2015) and an increase in the body size of sea otters during the decline do not indicate that bottom-up influences are responsible (Laidre et al., 2006; Monson, 2009). Researchers are seeking to understand their role in the estuarine food web and to quantify and understand the effects of human-caused stressors such as contaminants or nutrient inputs on sea otters in Elkhorn Slough, California. Although the data from these earlier surveys provide reasonably detailed assessments of (1) trends in sea otter abundance and distribution at several index islands (Fig. your claim with the current data on kelp? Washington's current sea otter population Accordingly, this project aims to understand the impact of multiple threats on sea otter abundance and trends, describe critical sea otter habitat needs, and determine the functional roles of sea otters in nearshore ecosystems. J. Mamm. Biol. /Pages 3 0 R ) or https:// means youve safely connected to the .gov website. Dean, T. A., and Bodkin, J. L. (2011). 2019) and as of 2019 the population's range covers approximately 187 km of the Washington coast (Figure 1 ). 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. The sea otter population in Southeast Alaska has grown extensively since the translocation of just over 400 sea otters to 6 locations in the late 1960s. A primary question is how food availability (ecosystem productivity; see Question 2) plays a role in limiting population and ecosystem recovery over long time periods. One view is driven by the conservation of sea otters as a species hunted to near extinction. Dramatic increase in sea otter mortality from white sharks in California. Trends in southern sea otter abundance based on 3-year running averages of raw survey counts. More typical are counts made from skiffs, larger vessels or aircraft in which detection probability is reduced relative to shore-based counts (however, see Cortez et al., 2016). 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. doi: 10.1046/j.1523-1739.1999.98124.x, Bodkin, J. L., Coletti, H. A., Ballachey, B. E., Monson, D. H., Esler, D., and Dean, T. A. Recommendations for future research and management that will allow full, pre-exploitation recovery and restoration of nearshore ecosystems should focus on at least seven key challenges. 32, 309326. Express the amount as a multiple of the imported population and as a percentage. (2018). endobj Webinar for K-12 educators: "Sea Otters and People.". Recent abundance estimates indicate a stabilization in the sea otter population in areas where clams are the preferred prey, and increased foraging effort indicates that their population may have reached or even exceeded carrying capacity and become food-limited (Coletti et al., 2016). Sea otter feeding on a California sea cucumber (Apostichopus californicus). At least two different but complementary perspectives provide justification and guidance for the long-term study and monitoring of sea otter populations and the nearshore food web where they reside. (PDF). They estimated the impact of killer whales on sea otter populations by comparing trends in population size and survival rates of individually marked otters between two adjacent locations on Adak Island: Clam Lagoon and Kuluk Bay. doi: 10.3106/1348-6160(2005)30[41:HASOSO]2.0.CO;2, Heithaus, M. R., and Dill, L. M. (2006). <> %PDF-1.4 An official website of the United States government. See how sea otters maintain the balance of kelp-forest ecosystems by consuming sea urchins The diet of sea otters in the KEJF includes a high proportion of intertidal mussels (58%), which have experienced a period of decline and subsequent recovery despite consistent site-specific settlement of small mussels over time (Coletti et al., 2016; Bodkin et al., 2018). Sea otters love grooming themselves and like to keep themselves meticulously clean, always grooming after eating. Proc. q"4\$j$\F,p1*'H`q $UU` FH'[TzVe6sQ=^)f}Ak Identifying the factors that regulate a species population density can provide insight into why population density varies spatially and temporally and when a recovering population has reached carrying capacity. because of these species reliance on kelp or seagrass habitat during critical phases of their life history. Temporal and spatial patterns in sea otter (Enhydra lutris) range expansion and in the loss of the Pismo clam fisheries. 34, 387404. The FWS estimated southern sea otter abundance in 2016 was 3,272 individuals, a record high since 1972. 1, A to C).Eelgrass meadows can consist of clonal perennial plants, which propagate vegetatively through rhizomes; sexually reproducing annual plants, which produce flowers and seeds; or a combination of . J. Exp. We attempt to assign a cause to observed changes by contrasting top-down (sea otter foraging efficiency and prey abundance) and bottom-up (recruitment, growth rates and environmental metrics such as temperature) processes among the four regions and the scale at which changes occur (e.g., similar changes across all areas vs. changes observed asynchronously among regions). Sea otters likely have been the top-down force structuring clam populations along the KATM coast as clams constitute 63% of the otters diet. This created a situation where two independent census methods generated counts with variable and un-quantified detection probabilities. The maritime fur trade in the late 18th and 19th centuries decimated and fragmented the sea otter population that once extended around the North Pacific Rim from northern Japan to central Baja California in Mexico. Moreover, white shark bites now account for >50% of recovered carcasses in California, with shark predation now limiting population expansion to the south as well as the north (Tinker et al., 2016). 5 0 obj 3, eds A. E. Dizon, S. J. Chivers, and W. F. Perrin (Lawrence, KS: Special publication of the Society of Marine Mammalogy), 197208. Sea otters are a keystone predator in the nearshore food web of the north Pacific Rim (Estes and Duggins, 1995). But population recovery has been . Their fur is made up of a dense underfur, ranging in color from brown to black, and longer guard hairs. Plot of southern sea otter population trends along the mainland coast of California and at San Nicolas Island over the period 1990-2013. Manage. In nearly all areas occupied by sea otters, primary production is provided by two pathways. Environ. doi: 10.1111/j.1748-7692.2003.tb01102.x, Estes, J. However, their pre-exploitation range had been seriously fragmented with widely scattered remnant populations in Russia, Alaska, and California. doi: 10.1007/s10021-013-9715-7. Evol. Mother sea otters nurse their pup for about eight months. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards. 68, 15351548. (2006). Mol. << Sea otters dive underwater or cleverly play dead when they sense danger. From 1965 to 1990, seven sea otter translocations were made into historically occupied habitat, resulting in five self-sustaining populations. A., Wheeler, P. A., Dahlhoff, E., Sanford, E., and Strub, P. T. (1997). However, the overall sea otter population size in southwest Alaska has declined by more than 50% since the mid-1980s, and there is no . 4 0 obj << Ecology 85, 33733384. Geological Survey3020 State University Drive EastSacramento, California 95819. Fish and Wildlife Service. 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. Predation (2014). Gorbics, C. S., and Bodkin, J. L. (2001). 54. Data are shown for independent otters (nonpups) and all otters for mainland California (blue; left axis), San Nicolas Island (red; right axis), and range-wide (squares; left axis) from 2012 onward, when both indices were combined to calculate the population index. Part 2 Top Stud. doi: 10.1890/08-0765.1, Williams, P. J., Hooten, M. B., Womble, J. N., Esslinger, G. G., and Bower, M. R. (2018). Sea otter conservation genetics, in Sea Otter Conservation, eds S. E. Larson, J. L. Bodkin, and G. R. VanBlaricom (London: Elsevier Academic Press), 97120. Provide a title and lable both the X and Y. As remnant populations increased their range and abundance, dedicated counts were made, eventually leading to the first systematic population monitoring (Barabash-Nikiforov, 1947; Lensink, 1962; Kenyon, 1969). As sea otters reoccupy northern Japan for the first time in over one hundred years, local fishing communities that harvest high-value invertebrates (e.g., uni sea urchin roe sells for $300 kg, and a sea otter can eat 45 kg per day) may place pressure on the government to limit the extent of their reoccupation. However, not all unoccupied habitats are equivalent in terms of available resources such as food and shelter, and these differences can result in geographic barriers, discontinuous distributions, and variable population densities. Secure .gov websites use HTTPS J. Trop. doi: 10.1111/j.1523-1739.2012.01951.x, Coletti, H. A., Bodkin, J. L., Monson, D. H., Ballachey, B. E., and Dean, T. A. If you ate 25 percent of your body weight daily, as otters do, how many quarter-pound hamburgers would you eat every day? D.somewhat misleading, because it does not make it clear that the southern sea otter population trends varied throughout the range. B. Bodkin, J. L. (2015). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. doi: 10.2307/2937159. One is through the macrophytes (kelps, seaweeds and sea grasses) that provide a stable source of productivity. Draw a dashed line across the graph to illustrate where you figured out carrying capacity should be. Oceanogr. 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. <> Factors that regulate female densities are not well known, but small annual home ranges are suggestive of behavioral mechanisms. Figure 1. While these two examples focus on the recolonization by sea otters of areas without fisheries conflicts, existing long-term monitoring programs, such as GWA, should guide the development of research questions that focus on the effects of recolonization on commercially viable prey species. doi: 10.1016/j.jas.2011.12.006, Tallis, H. (2009). Also, no sea otters were ever observed foraging in these areas, probably due to the lack of inverte- brates (author's pers. The San Nicolas population remained small (20 animals) for decades, and the translocation program was administratively deemed a failure in the early 2000s (Federal Register 77, 2012; p. 75266). You will plot the data, provided for each organism in order to determine the response to the variable. doi: 10.1890/07-1818.1, PubMed Abstract | CrossRef Full Text | Google Scholar, Arkema, K. K., Guannel, G., Verutes, G., Wood, S. A., Guerry, A., Ruckelshaus, M., et al. However, in the 1700s and. Doroff, A. M., Estes, J. Deep-Sea Res. Development of an altricial mammal at sea I: activity budgets of female sea otters and their pups in Simpson Bay. Can. Ecol. Currently, it appears that shark predation is an important factor limiting range expansion, particularly in the northern end of the range. 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. A., and Burge, R. T. (1986b). (2012). /Length 9 0 R Resource Competition, Space Use and Forage Ecology of Sea Otters, Enhydra lutris, in Southern Southeast Alaska. J. Parasitol. The importance of marine predators in the provisioning of ecosystem services by coastal plant communities. Southern sea otters, also known as California sea otters, live in the waters along the central California coastline. Fish and Wildlife Service, 2013) from Attu at the western tip of the Aleutians to a boundary drawn down the middle of lower Cook Inlet, approximately 2,500 linear km. New technology is needed to overcome these tagging limitations. Dis. Van Wormer, E., Miller, M. A., Conrad, P. A., Grigg, M. E., Rejmanek, D., and Carpenter, T. E. (2014). doi: 10.1016/B978-0-12-801402-8.00005-6, Lee, J., Watson, C., Trebilco, R., and Salomon, A. K. (2016). The publication, as well as Science News magazine, are published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education. (2009). In addition, continuing sources of information are needed for: (1) the abundance and distribution of prey, (2) sea otter dietary preference and consumption, (3) seasonal and annual primary productivity and oceanographic conditions, (4) predator abundance, and (5) the magnitude and sources of mortality, including the presence of diseases that decrease sea otter longevity or affect their prey. This question is relevant to predicting population trends (i.e., describing the status of populations) and developing management policies, which will contribute to the full recovery of sea otters to pre-exploitation levels, reoccupation of their historical range, and restoration of nearshore ecosystems (Davis et al., 2019). The use of quantitative models in sea otter conservation, in Sea Otter Conservation, eds S. E. Larson, J. L. Bodkin, and G. R. VanBlaricom (London: Elsevier Academic Press), 257300. The population never grew as expected and in 2012,the FWS declared the translocation a failure. A. They found that a 50% reduction in the poaching of northern abalone was necessary to reach a short-term recovery goal of halting further declines in northern abalone density in the presence of sea otters. stream What type of data would you need to collect and analyze? Understanding the factors that regulate sea otter density will be challenging and likely require focusing on a few index sites that are representative of the variety of littoral habitats occupied by sea otters around the North Pacific Rim. They dive down and forage on the seafloor for food, using rocks to dislodge prey and open shells. B., Harris, M. D., and Ames, J. (2013). They have flattened and rounded molars for crushing and chewing food. Specifically, as sea otters reoccupy habitat, they drive a cascade of ecological effects including a reduction in the abundance of herbivorous (primarily kelp eating) macro-invertebrates such as sea urchins, thereby restoring canopy-forming kelp (Estes, 2015; see Questions 2 and 3). 52, 7076. J. 11, 17791790. (2015). Ph.D. thesis, University of California, Santa Cruz, CA. 6) 13, 219229. doi: 10.1371/journal.pone.0091235, Hatfield, B. The sea otter . Sherrod, S. K., Estes, J. Predator-driven natural selection on risk-taking behavior in anole lizards. Status and distribution of sea otters in Alaska. Surveys to monitor sea otter population abundance are generally of two types. Sea otters have the thickest fur of any mammal/animal. /Producer ( Q t 5 . However, it is likely that subpopulations within MUs are functionally independent as well. Sea otters need to conserve energy, which means that uninterrupted rest is an important part their well-being. the documents to your computer and open them with Adobe Reader. Ecosphere 7:e01604. In contrast to KEFJ, Katmai National Park and Preserve (KATM) in southwest Alaska has had a rapidly increasing sea otter population since 1989 (Estes, 1990; Bodkin et al., 1999; Bodkin, 2015). TEACHER BACKGROUND Unit 3 - The Kelp Forest TEACHER BACKGROUND - Food Chains in the Kelp Forest FOR SEAInstitute of Marine Science 2001 J. Mothers care for their young while floating on their backs. Sea otters: their role in structuring nearshore communities. 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. doi: 10.1890/08-2086.1, Menge, B. A. That is, compared to the complex coastline of many areas in Alaska and Canada where remnant or translocated populations could expand in many directions simultaneously (allowing higher population growth rates; Bodkin et al., 1999), the California population could expand only in two directions (north and south). Ecology 73, 413428. Science 185, 10581060. The southern sea otter has reclaimed only about 13% of its historical range, and its population size is far below its estimated historical population size in California, about 17,000 (though it could be as low as 10,000 or as high as 30,000), a number that does not include the historical populations in Oregon and Baja California. They are nocturnal mammals, which means they prefer to hunt and move around at night. Am. Barabash-Nikiforov, I. I. Coastal habitats shield people and property from sea-level rise and storms. Foraging behavior and prey of sea otters in a soft- and mixed-sediment benthos in Alaska. Draft Periodic Status Review for the Sea Otter in Washington. Manage. 3 0 obj obs.). Link will appear as Sea Otter Facts & Worksheets: https://kidskonnect.com - KidsKonnect, August 5, 2018. 19. The research is being led by a partnership of the U.S. Geological Survey, University of California-Santa Cruz, California Department of Fish and Wildlife, the Monterey Bay Aquarium, and the Elkhorn Slough National Estuarine Research Reserve (ESNERR), with assistance from other partners. Disease, parasites and predation were identified as possible factors (Miller et al., 2002, 2004; Kreuder et al., 2003; Conrad et al., 2005a,b, Johnson et al., 2009), but it appeared unlikely that these factors fully explained the populations slow growth. doi: 10.1016/j.ecolecon.2008.10.016. The average body mass for males is about 88 pounds, with a range of 49-99 pounds; females range from 31-73 pounds. The development of commercial and recreational shellfish fisheries was fueled by the high abundance of benthic invertebrates that developed during the absence of their natural predator, the sea otter. Since 1993, we have conducted aerial surveys of sea . Ser. These are challenging goals, but with well-articulated uncertainties, the results could be useful to managers in anticipating and planning for sea otters effects on the abundance of commercially or recreationally targeted species of shellfish. August 5, 2018 Strub, P. A., Dahlhoff, E., and Burge, T.! 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