Once containing more than half of the world’s sea otters, this population segment, which ranges from Kodiak Island through the western Aleutian Islands, has undergone an overall population decline of at least 55–67 percent since the mid-1980s. After reading: What other animals might be considered “keystone species”? Otters do not have blubber like other marine mammals, such as whales. The results of this study indicate an improved overall health of sea otters over the period of decline and suggest that limited nutritional resources were not the cause of the observed reduced population abundance. Further, source-sink population dynamics can explain the slow recovery observed in the spill-affected western Prince William Sound sea otter population and are consistent with available data. We also continue to study the role of sea otters in structuring nearshore communities using a time-series of data we have collected in Glacier Bay in Southeast Alaska where the sea otters first appeared in the early 1990's and since have reoccupied the entire Bay with an estimated population of over 5000 animals. We collected focal observations of sea otters foraging at sites across the gradient in varying habitat types between 2010 and 2017. The average annual growth rate in southern Southeast Alaska (7.8%) was higher than northern Southeast Alaska (2.7%); however, growth varied at the sub‐regional scale and there was a negative relationship between growth rates and the number of years sea otters were present in an area. Baculum length increased rapidly at sexual maturity and was a good indication of maturity status (< 14cm = immature). Introduction. Our model improves upon previous analyses by partitioning and quantifying sources of estimation error, accounting for over‐dispersion of aerial count data, and providing realistic measurements of uncertainty around point estimates of abundance at multiple spatial scales. The return to pre-spill numbers and mortality patterns suggests a gradual dissipation of lingering oil over at least two decades, to the point where continuing exposure is no longer of biological significance to the WPWS sea otter population. We respond to pollution events, such as boat wrecks and oil spills that may threaten sea otters. As mammals, sea otters have hair and feed their babies milk. We track sea otter population abundance, trends, and distribution throughout Alaska using aerial and boat-based surveys. The nearshore ecosystem is broadly recognized as highly susceptible and sensitive to a variety of both natural and human disturbances on a variety of temporal and spatial scales. Our models resulted in hind-cast (1989-2003) predictions of net population growth and range expansion that closely matched observed patterns. These sea otter surveys are conducted cooperatively by scientists of the U.S. Geological Survey, California Department of Fish and Wildlife, U.S. Instead, they have an extremely thick coat of fur to keep warm - no animal has thicker fur. More recently the theory as to why the sea otter population is not growing in California and is stagnant in its growth trend is the nature of the coastline in California. US Geological Survey conducts these surveys with teams of scientists’ part of the Western Ecological Research Center. Behavior. the southern sea otter stock. Dr. Estes and his colleagues began an ecological detective hunt to uncover the cause of the declining otter population. “The population index has exceeded 3,090 for the first time, and that’s encouraging,” said Lilian Carswell, Southern Sea Otter Recovery Coordinator for USFWS, “but sustained population growth will require range expansion, which means that sea otters will somehow have to get past the shark gauntlets near the ends of the current range. Using demography and movement behavior to predict range expansion of the Southern Sea Otter, Activity Budgets Derived From Time‐Depth Recorders in a Diving Mammal. Males (n = 5) and individuals residing in recently occupied habitat (n = 4) spent 0.28-0.30 of their time foraging (6.7-7.2 hr/d), 0.17-0.18 of their time in other diving behaviors (4.1-4.3 hr/d), and 0.53-0.54 of their time resting (12.7-13.0 hr/d). Population. Quantitative models of range expansion have rarely been applied to large vertebrates, although such tools could be useful for restoration and management of many threatened but recovering populations. The translocation and subsequent population growth and range expansion of the northern sea otter (Enhydra lutris kenyoni) in Washington State over the last five decades has created a spatio‐temporal gradient in sea otter occupation time and density, and acts as a natural experiment to quantify how sea otter population status and habitat type influence sea otter diet. In addition to larger asymptotic values for mass and length, the rate of growth towards asymptotic values was more rapid in the 1990s than in the 1960s/70s: sea otters reached 95% of asymptotic body mass and body length 1-2 years earlier in the 1990s. Consistent with these differences, sea otters residing in more recently occupied habitat captured more and larger clams (Saxidomus spp., Protothaca spp., Macoma spp., Mya spp., Clinocardium spp.) Why isn’t the sea otter population now growing as fast as it once was … Fluctuations in population density can produce profound changes in ecological constraints, influencing growth and sexual maturity of animals in a population, and can transform the ecology of newly populated ecosystems. Sea Otter Coloring Sheet - Northern Sea Otter (PDF) ... 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. This was true for nearly all species in the Gulf of Alaska and remains an impediment in assessing injury from such catastrophes across most landscapes today. Could residual oil from the Exxon Valdez spill create a long-term population ‘‘sink’’ for sea otters... Report number: Endangered Species UPDATE Vol. The nearshore is also an important triple interface between air, land, and sea that provides linkages for transfer of water, nutrients, and species between watersheds and offshore habitats. Fish and Wildlife Service anticipated de-listing by 2000. Analyses of data collected from, In addition to forecasting population growth, basic demographic data combined with movement data provide a means for predicting rates of range expansion. Large scale ecosystem level studies of nearshore species and habitats most affected by the spill completed in 1999, found evidence of long-term spill effects among nearshore species dependent on a nearshore food web where benthic invertebrates transfer primary production to upper level consumers such as sea otters and sea ducks. Which populations were wiped out, and in what order? We compile available survey data for Southeast Alaska and fit a Bayesian state‐space model to estimate past trends and current abundance. Current Population Trend The trend for this stock of sea otters has generally been one of growth (Pitcher 1989, Agler et al. Although wild animal populations always rise and fall to some degree, a decline of this size cried out to be explained. The historic or natural carrying capacity of disturbed ecosystems can not be directly assessed. We hypothesize that the patchy nature of residual oil left in the environment has created a source-sink population dynamic. Why? Growth models for body mass and length were fitted to data collected from 1842 sea otters Enhydra lutris shot or live-captured throughout south-west Alaska between 1967 and 2004. Video shows underwater footage of specially trained divers capturing a Southern Sea Otter. In addition to these basic predictions, we emphasize how to make these modeling predictions useful in a management context through the inclusion of parameter uncertainty and sensitivity analysis. Using morphometric measurements and reproductive tracts collected from 40 sea otters by an Alaska Native subsistence hunter, we evaluated growth rates and age at sexual maturity of male sea otters near Gustavus, Alaska. schools, special events, Tribal and community meetings. We sit on expert panels to provide the most current information on sea otter management and research and provide peer reviews for reports and publications. Asymptotic values of body mass were 12-18% higher in the 1990s than in the 1960s/70s, and asymptotic values for body length were 10-11% higher between the same periods. Despite difficulties with implementation, no alternatives have arisen to replace this paradigm for marine mammal conservation. Comparing the current population estimate with that of the previous stock assessment reports suggests that this growth trend is continuing. 38. Trends in Sea Otter Population Abundance in Western Prince William Sound, Alaska: Progress Toward Recovery Following the 1989 Exxon Valdez Oil Spill By J.L. Current Population Trend As recommended in the Final Revised Recovery Plan for the Southern Sea Otter (U.S. Long‐term diet studies can provide a broader picture of sea otter population status in Washington State. are a salient example of a keystone species exerting top‐down control on ecosystem community structure. Often data can be collected easily, and they usually reflect current environmental conditions for assessing human-induced changes in the environment. Care must be taken to choose indices that reflect integration over sufficient time to avoid variation due to momentary conditions, such as annual weather cycles. We are using this situation in Glacier Bay as a laboratory to experimentally evaluate the role of sea otter in structuring coastal marine communities in a predominately soft sediment habitat. Our results suggest that residual oil can affect wildlife populations on time scales much longer than previously believed and that cumulative chronic effects can be as significant as acute effects. During the absence of sea otters, many of their prey populations responded to reduced predation through increased densities and sizes. Sea otters are amphibious mammals. Population age structures differed significantly between the 1960s/70s and the 1990s with the latter distribution skewed toward younger age classes (indicating an altered lx function) suggesting almost complete relaxation of age-dependent mortality patterns (i.e. 13 No. We fit models using the age distributions of both living and dying animals and estimates of sea otter population size to predict the number of sea otters in the hypothesized sink population and the number lost to this sink due to chronic exposure to residual oil. Growth curves demonstrated a significant increase in body mass and body length at age in the 1990s. At the time of the spill, the sea otter (Enhydra lutris) population inhabiting the spill area suffered substantial acute injuries and loss. The predicted rate of southward range expansion (median = 5.2 km/yr) was sensitive to both dispersal and survival rates; elasticity analysis indicated that changes in adult survival would have the greatest potential effect on the rate of range expansion, while perturbation analysis showed that variation in subadult dispersal contributed most to variance in model predictions. The GIS shapefile "Census summary of southern sea otter 2018" provides a standardized tool for examining spatial patterns in abundance and demographic trends of the southern sea otter (Enhydra lutris nereis), based on data collected during the spring 2018 range-wide census. Implementation of this approach is fraught with practical problems: population levels are difficult and costly to estimate and current carrying capacity is essentially impossible to measure through environmental assessment. Long term continuation of studies investigating mortality from the annual collections of beach cast sea otter carcasses implicates elevated mortality as the factor contributing to delayed recovery, and suggests that chronic mortality after the spill meet or exceeded the acute mortality experienced after the spill. The nearshore monitoring program focuses on the nearshore benthic food web in the northern Gulf of Alaska. Sea otters pray on sea urchins and urchins eat kelp. One of the factors limiting our ability to clearly understand and document the spill effects was a lack of accurate estimates of sea otter abundance. Our current understanding of the dynamics of the southern sea otter population is largely based on MMS-funded studies conducted during the 1980s (Siniff and Ralls, 1988), at a time when the population was increasing. Habitat characteristics are primary determinants of nearshore marine communities. The California otter population is increasing at approximately 5 to 7% per year, compared with 17 to 20% per year for the more northerly populations [2]. In particular, measures of biological features that experience density-dependent change provide indirect means of determining population status. All content in this area was uploaded by Daniel H Monson on Feb 02, 2018, ... Sea otter population dynamics vary geographically (, ... From 1983From to 1994, spring survey results indicated that the population was increasing about 5-6% per year. Monitor the sea otter population .....52 2. The fundamental force behind population change is the balance between age-specific survival and reproductive rates. Sea otters (Enhydra lutris ssp.) This approach requires estimates of: (1) current population level, and (2) carrying capacity of the undisturbed habitat. food chains and web's worksheets, coral reef community coloring pages and ocean coral reef coloring page are three main things we want to present to you based on the. The status of a population is expressed in terms of the population level as a fraction of the mean of natural (undisturbed ecosystem) equilibrium level. Ballachey, and G.G. Bodkin, B.E. For many species, demographic rates change as the population’s status (i.e., relative to prey resources) varies. With the exception of 13 small remnant populations, sea otters were extirpated from their historic range in the north Pacific Ocean during the 18th and 19th centuries as a result of the commercial harvest for their fur. Biochemical and gene techniques suggested that lingering oil may have contributed to a protracted recovery period for nearshore species. There is good evidence that the recent declines in sea otters in SW Alaska are related to killer whale predation and the Exxon Valdez oil spill reduced the size of the western Prince William Sound population in 1989. Undertake research that will facilitate and enhance recovery efforts .....57 7. Data collected in 2004 suggest a continued increase in body size, with nearly all data points for mass and length falling significantly above the 1990s growth curves.

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