sea otter population trends worksheet
Predation can also force sea otters into refugia that are less accessible to predators, thereby reducing available habitat and secondarily increasing competition for food in safe areas (Heithaus and Dill, 2006; Heithaus et al., 2008; Wirsing et al., 2008; Willems and Hill, 2009). Evidence that this decline is due to the top-down effects of killer whales includes the following: (1) the observed rate of killer whale predation events is consistent with the expected frequency relative to observer effort, (2) declines have occurred in outer coastal habitats but not within lagoon habitats inaccessible to killer whales (e.g., Clam Lagoon on Adak Island), (3) carcasses deposition on beaches has not increased during the decline (i.e., sea otters consumed entirely), (4) energetic calculations show that only a small number of killer whales could explain the decline (i.e., it is feasible that one pod caused the entire decline), (5) the geographic extent of the decline indicates that the cause is not localized (i.e., not from a point-source of contaminants), (6) the lack of evidence of disease or toxins in live-captured animals indicates that disease is not the cause, (7) there has been a dramatic nearshore shift (to within 100 m from shore) in sea otter distribution with the only remaining areas of outer coast sea otter concentrations (hotspots) characterized by shallow, complex reef habitats that are less accessible to killer whales, and (8) sea otter behavior when disturbed has changed (i.e., before the decline sea otters would move offshore, but after the decline they move close to shore or haul out). A .gov website belongs to an official government organization in the The sea otter is the largest otter, reaching 100-160 cm (40-65 inches) long and weighing 16-40 kg (35-90 pounds) when fully grown. In addition to abundance, trends, distribution, and forage energy intake across seasons and years, these replicated surveys provide information on the precision of data achieved by quarterly survey effort. These aquatic members of the weasel family are often seen floating on their backs. Population reconstructions that (a) excluded natural immigration and surrogate-releases, (b) excluded releases but . 24, 115. /Type /XObject Write a letter explaining why an organization should give you money for your work. doi: 10.1016/B978-0-12-801402-8.00001-9, Larson, S. E., Ralls, K., and Ernest, H. (2015). WPWS sea otter population in 10-23 years, with maximum annual growth rates from 10 to 14 percent. (2017). J. Arch. Adult sea otters may grow up to 5 feet in length. The main threat to sea otters used to be hunting by native people who used their meat as food and their fur for clothing. your claim with the current data on kelp? However, it is likely that subpopulations within MUs are functionally independent as well. Predicting ecological consequences of marine top predator declines. Reliable information on sea otter population growth and range expansion is needed to enable communities to adapt as shellfish fisheries are impacted. The goal of this research program is to understand the factors affecting the growth and dynamics of sea otter populations in the western US coastal waters, including listed populations in California and southwestern Alaska. Demographically and ecologically, sea otter populations operate at smaller spatial scales than currently recognized by management agencies (i.e., at the level of subspecies and stock designations that currently span 1,000s of km). Received: 02 July 2018; Accepted: 21 December 2018;Published: 21 January 2019. Sea otters are a keystone predator in the nearshore food web of the north Pacific Rim (Estes and Duggins, 1995). Fish and Wildlife Service. 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. RD organized and integrated this article and wrote the Introduction, Question 2, and the Conclusion and Recommendations. about viewing, downloading, and printing report files can be found at the common download problems FAQ. Mar. The 2017 count declined somewhat, to 3,186 otters, but still exceeded the potential delisting threshold for a second straight year. B., Harris, M. D., and Ames, J. Variation in their current status, and in the rate and pattern of recovery, provides an opportunity to use the comparative approach to elucidate how various natural and human-caused stressors affect population health and dynamics. Sea otters are born swimmers with long, sleek, streamlined bodies with webbed feet. While eliminating the predators of sea otters is not scientifically advisable or legally feasible, other management options exist. More recent high-resolution sampling of the southern sea otter population in California did find evidence for isolation by distance and cryptic genetic structure with implications for estimates of effective population size (Gagne et al., 2018). Coast. Biol. 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). This manuscript includes a review of past research and does not include any new data or metadata releases. Figures of Pages from the Monitoring and Research Plan for Southern Sea Otter Military Readiness Area. 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 . 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). Science 185, 10581060. (1990). In addition, the Commission noted the need to update the southern sea otter stock assessment report more frequently. These include but are not limited to sea otters and their prey. Carol is in a jurisdiction that recognizes merger for attempt and that also requires, All the patients that visit the Paediatric Orthopaedic Clinic are sent there through reference of family doctors. 65, 75100. 4) The success of the translocations to Southeast Alaska, British Columbia, Canada, and Washington state helped mitigate declines in the Aleutian Islands. U.S.A. 110, 1531315318. /Filter /DCTDecode 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). Measures of effective population size in sea otters reveal special considerations for wide-ranging species. (2012). Oyster mariculture using net bags or enclosed trays occurs in Kachemak Bay and Prince William Sound, Alaska and on the west coast Vancouver Island, British Columbia, despite the presence of large numbers of sea otters. Although the FWS declared the translocation a failure, it is quite possible that otter numbers at San Nicolas will continue to grow. 52, 7076. New technology useful in documenting sea otter dispersal along with genetic analyses on microgeographic scales are needed to understand historical and contemporary gene flow, especially in populations where predation may have selected against dispersal behavior. Mar. These conflicts ultimately may affect a fishery through area closures or required gear modifications. 8:e2852. Evol. What is the general trend in the kelp population that is seen between 0-20 years? Following almost two centuries of commercial hunting, sea otter populations were severely reduced; surviving southern sea otters consisted of a small colony of otters along the remote Big Sur coast of central California. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Estes, J. (2) Understanding factors that regulate sea otter population density: Sea otter density at the landscape scale is a mosaic of local densities that depend on many factors, which vary over different time scales. (2001). Instruments attached to the hind flippers are susceptible to removal or destruction by the animal and must be extremely small and lightweight to avoid tearing the flippers webbing. } !1AQa"q2#BR$3br The Sci. Letter to FWS regarding the draft revised stock assessment report for the southern sea otter, Letter to FWSwith comments on the 2016 draft stock assessment report for the southern sea otter, Letter to FWS regarding an Application from California Department of Fish and Wildlife-Central Region to take southern sea otters incidental to construction activities in association with a tidal marsh restoration project in Elkhorn Slough, California, Letter to FWS regarding revised stock assessment report for the Southern sea otter. Here, we give examples of the challenges in defining sea otter populations and the consequences of managing populations at an inappropriate scale. These are great stretches of algae, analogous to terrestrial woodlands, in which kelp fills the role of trees. Wildl. 13, 219229. Both conservation and management will benefit from a multi-faceted approach to monitoring not only sea otters, but also the nearshore ecosystems they occupy. Teacher Resources. 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). doi: 10.1038/nclimate2763, Atwood, T. B., and Hammill, E. (2018). 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. Med. D.somewhat misleading, because it does not make it clear that the southern sea otter population trends varied throughout the range. Sea otters are susceptible to entanglement and drowning in gill nets (Wendell et al., 1986a; Herrick and Hanan, 1988; Forney et al., 2001) and to entrapment and drowning in finfish, lobster, and Dungeness crab traps (Hatfield et al., 2011). Figure 1 Open in figure viewer PowerPoint However, this technique is labor intensive, logistically expensive, and not practical for extended periods in remote areas that are accessible only by boat or aircraft. /Type /Catalog Approximately how much have sea otter populations increased from 1969-70 to today? A second method to monitor abundance is to correct for sighting bias of animals not detected and areas not surveyed. Coinciding with recent population growth, the sea otter distribution, which previously tended to concentrate on the west side, appears to have shifted toward an expansion of use in the north and especially greater seasonal use in the north and south during winter and spring. Obtaining this information, especially in more remote areas of the sea otters range, will not be easy and will require coordinated research over decades (see Question 3). (1983). What other animals might be considered keystone species? PLoS One 8:e65435. However, these land-based predators likely are not having significant population-level effects. The mother will hold her pup on her chest to nurse it and gradually teach it to swim, forage/hunt/retrieve food. endobj Plot of southern sea otter population trends along the mainland coast of California and at San Nicolas Island over the period 1990-2013. Acad. Currently, it appears that shark predation is an important factor limiting range expansion, particularly in the northern end of the range. Dramatic increase in sea otter mortality from white sharks in California. The first is considered a census, where it is assumed that all animals in an area are counted, and precision is not usually estimated. B., Staedler, M. M., et al. 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. Mamm. Tinker, M. T. (2015). doi: 10.1080/08920750600860282, Lubina, J. Due to their thick, soft pelts, sea otters were hunted extensively until an international ban was enforced to prevent their extinction. 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). Forney, K. A., Benson, S. R., and Cameron, G. A. %&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz Weitzman, B. P. (2013). When otters disappear, the urchin population explodes and quickly "deforests" the . (1988). 1999). (2012). Mamm. Provide a title and lable both the X and Y. >> Intuitively this explanation makes sense, but it took decades for biologists to fully realize how a population functioning at small spatial scales in conjunction with shoreline complexity could explain the relatively slow growth of the California population, which for decades was a source of concern for sea otter researchers and conservation organizations. Draw a dashed line across the graph to illustrate where you figured out carrying capacity should be. Director, Western Ecological Research CenterU.S. Mamm. Oecologia 177, 645655. 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 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. Ecol. Otters maintain the ecosystem by eating sea urchins, which feed on kelp. Fish Game 72, 197212. endobj J. Hyg. 4 0 obj What kinds of other animals share the sea otters habitat? The sea otter . What caused the loss of sea otters along the coasts of Washington State and Oregon? J. Mamm. The Commission also consults periodically with the FWS and marine mammal facilities to resolve questions about the placement of non-releasable otters from this population. After 12 weeks of being fed and groomed, a pup is considered a juvenile, Behavioral Traits and Conservation Status. Sea otters can hold their breath for up to five minutes but dives typically only last about one minute. Gelatt, T. S. (1996). WERC collaborates with other research scientists to conduct annual population surveys of the southern sea otter -- a federally listed threatened species. The guard hairs can be brown to black to silver. They are a keystone species, so if they die, so will much of their habitat. Fish and Wildlife Service initiated a sea otter monitoring and research plan to determine the effects of military readiness activities on the growth or decline of the southern sea otter population at San Nicolas Island. in giant kelp forests. Sci. (2018). magazine, are published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education. 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. Course Hero is not sponsored or endorsed by any college or university. Barabash-Nikiforov, I. I. Sea otters do hold hands. Fort Collins, CO: National Park Service. Johnson, C. K., Tinker, M. T., Estes, J. /Type /ExtGState Bodkin, J. L., Ballachey, B. E., Cronin, M. A., and Scribner, K. T. (1999). International legal protection and translocations in the 20th century have enabled sea otters to recover and reoccupy historical habitats with varying levels of success. (2018). DM wrote Questions 1 and 7. Clim. 39, 15531571. Can. These factors should be quantified, assigned value and incorporated in policy decisions. Proc. Alaska. Gagne, R. B., Tinker, M. T., Gustafson, K. D., Ralls, K., Larson, S., Tarjan, L. M., et al. 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. Following their near extirpation, there was little effort to monitor them because remnant populations were small, remote and in some cases unknown. Currently, radio telemeters are implanted in the abdominal cavity, which precludes the use of satellite-linked devises because of antenna limitations. Share sensitive information only on official, secure websites. (2015). He's seen the island's population of sea otters soar over the last handful of years . Wendell, F. E., Hardy, R. A., and Ames, J. They spend around 40% of their time hunting and eating and eat about 25% of their body weight every day. Wendell, F. (1994). Relationship between sea otter range expansion and red abalone abundance and size distribution in central California. Evaluating the status of individuals and populations: advantages of multiple approaches and time scales, in Sea Otter Conservation, eds S. E. Larson, J. L. Bodkin, and G. R. VanBlaricom (London: Elsevier Academic Press), 119155. Ecology 99, 524535. Infect. 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. In contrast, areas to the east still have healthy, growing populations, including those along the southern Alaska Peninsula (Coletti et al., 2016) and Kodiak Island (Monson and DeGange, 1995). Secure .gov websites use HTTPS Sea otters were presumed extinct in California after the 19th century fur trade years, but were rediscovered in the 1930s by the public, when as few as 50 animals were documented persisting in nearshore areas off the coast of Big Sur. To accomplish this, we have forged partnerships with scientific collaborators from the Federal, State and private sector, to produce high-quality scientific information on the role of various stressors in limiting sea otter abundance, and to ensure this information's relevance and application to current conservation problems. Sea otters are now protected by law, and their numbers are considered stable. Fort Collins, CO: National Park Service. A. 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. Among the dangers they face today are oil spills, shark attacks, conflict with humans, competition for food, and habitat degradation. Calif. (2018). By then, only a few thousand otters remained, including a small colony of about 50 otters along the coast of central California. Riedman, M. L., and Estes, J. More recent modeling demonstrated that the California population was not acting as one unit (Tinker et al., 2006) and that the linear nature of the California coast limited population growth simply because of its two-dimensional nature (Tinker, 2015). 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. Natural Resource Report NPS/SWAN/NRR2017/1443. Acad. Both perspectives recognize the important role sea otters play in structuring the shallow, littoral ecosystem, but the perspectives differ in time and space. Otter meat is nutritious and edible and was a valuable source of food for many people for many years. How would the marine community be affected? 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. 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. Geoduck clam (Panopea abrupta) demographics and mortality rates in the presence of sea otters (Enhydra lutris) and commercial harvesting. The recovery plan specifies that the species should be considered for delisting when the average population level over a three-year period exceeds 3,090 animals. Transmission of toxoplasma: clues from the study of sea otters as sentinels of Toxoplasma gondii flow into the marine environment. /SM 0.02 17, 632647. Future research should focus on developing technology to determine sea otter dispersal distances in both predator-impacted areas (i.e., the Aleutian Islands) and areas without significant predation pressure. Defining populations at smaller spatial scales could add flexibility to management options, which now center on balancing the interests of several user groups. An important density-independent factor is primary production, which injects carbon and nutrients into the food web (see Question 3). Nat. Stock structure of sea otters (Enhydra lutris kenyoni) in Alaska. Between the late 1970s and early 1990s, the sea otter population range was limited to the outer coast of Washington between Makah Bay and Destruction In addition, wolves (Canis lupus) are suspected to take live sea otters both on the Alaska Peninsula and near Glacier Bay in Alaska. Females with pups will occupy areas that provide important resources such as food and protection from wind and waves. Sign Me Up. Although fishery-related conflicts historically have received the most attention, managers need information sufficient to assess the full suite of effects associated with sea otter range expansion (whether resulting from natural population growth and movement or from future translocations), including beneficial environmental and socioeconomic effects. Sci. % <> Sea otters have webbed feet, water-repellent fur to keep them dry and warm, and nostrils . JB wrote Question 4. Nat. That is, localized harvests limited sea otter impacts on local subsistence shellfish resources while not having a significant impact on the range-wide sea otter population. 41, 172182. U.S.A. 94, 1453014535. 5 0 obj Social organization of sea otters in prince william sound, Alaska. A., Tinker, M. T., Bodkin, J., Monson, D., and Schneider, K. (2006). Sea otter pups are susceptible to predation by bald eagles (Haliaeetus leucocephalus) in areas where they co-occur (Sherrod et al., 1975; Anthony et al., 2008). Look in the library and on the Internet to learn what animals live in a kelp forest. While goals may vary, either survey type can generate population trend data, and it is important that accepted protocols be followed consistently to allow comparisons over space and time. 75, 978989. In addition, the risk of oil spills remains an ongoing concern. Specifically, we 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. The Commission identified a need to establish an observer program with sufficient coverage to obtain reliable information on the rate and circumstances surrounding the entrapment of sea otters in such gear. 304 strandings represent about 11 percent of the current population estimate, an increase from the 8 to 10 percent reported in the recent decade. Their fur is made up of a dense underfur, ranging in color from brown to black, and longer guard hairs. /Producer ( Q t 5 . The most recent estimate of sea otter population abundance in Washington was 2,785 individuals (2,632 independents, 153 pups; Jeffries et al. 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. (1962). The Commission recommended ways to improve the potential biological removal estimate. Conserv. The History and Status of Sea Otters in Alaska. An analysis of sea otters and kelp forests. Genetic studies of sea otters provide evidence for major groupings, but no evidence of microgeographic structuring (see review in Scribner et al., 1997). Monitoring efforts have varied in frequency and type across years. Sea otters versus sea stars as major clam predators: evidence from foraging pits and shell litter. BIOLOGY205 - Population Trends1 2 2 .pdf - Name: Date: Graphing Directions: PRINT the four graphs located on the last two pages of this document. Minutes but dives typically only last about one minute other animals share the sea otters and their prey,. 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