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sea otter population trends worksheet

We hypothesize that the patchy nature of residual oil left in the environment has created a source-sink population dynamic. Much of our knowledge of the role of sea otters as a source of community variation resulted from the spatial and temporal pattern of sea otter population recovery since their near extirpation about 100 years ago. Fish and Wildlife Service. Animals in this study reached sexual maturity earlier than previous studies, at age 3–4 years. Increasing age and number of pregnancies were associated with a higher risk of ELS. 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. The canopy forming kelps and eelgrass beds found in the nearshore provide primary production and structure to nursery habitats, and can dissipate wave energy, thus reducing coastal erosion, and serve as a carbon “sink” capable of storing substantial amounts of atmospheric carbon dioxide. As a result, populations of sea otters in the Aleutian Islands have declined from an estimated 60,000 animals in the mid-1980s to under 10,000 by 2000. ForÂ, We monitor health, disease, and patterns of mortality for sea otters in Alaska by; assessing information from ‘healthy’ live-captured animals, assessing information from stranded animals, and conducting forensic necropsies on dead sea otters. Additionally, we found that habitat type explained 1.77 times more variance in sea otter diet composition than sea otter cumulative density. 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. schools, special events, Tribal and community meetings. We collected focal observations of sea otters foraging at sites across the gradient in varying habitat types between 2010 and 2017. This Shape file includes a series of summary statistics derived from the raw census data, including sea otter density (otters per square km of habitat), linear density (otters per km of coastline), relative pup abundance (ratio of pups to independent animals) and 5-year population trend (calculated as exponential rate of change). oil and gas exploration in Cook Inlet) to make sure development is not in violation of the Marine Mammal Protection Act and the Endangered Species Act.  We review applications forÂ, We conduct outreach and education about sea otters, their conservation, and the Marine Mammal Protection Act at many different venues i.e. The overall average activity budget (proportion of 24-hr/d) was 0.37 foraging (8.9 hr/d), 0.11 in other diving (2.6 hr/d), and 0.52 nondiving time (12.5 hr/d). Kuluk Bay is on an open coast, so sea otters there are exposed to killer whales. Following a review of the history, utility, and potential of indirect methods for population assessment, we suggest that characteristics of populations, and the individuals within, give a better assessment of ecosystem conditions and relationships than can be achieved through direct measurement. 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. The student measured the kelp abundance at 4 different sites, then spent a day at each site and marked whether otters were present or absent every 5 minutes during daylight hours. In particular, measures of biological features that experience density-dependent change provide indirect means of determining population status. Levels for PCDD and PCDF were extremely low in all otter populations. 6. Similar methods could aid in the management of other recovering populations. In this regard, some species serve as indicators of trophic relationships and ecosystem state. Ogden A (1933) Russian sea otter and seal hunting on the California coast. Our results suggest that the sink population has remained at just over 900 individuals (95% CI: 606-960) between 1990 and 2009, during which time prime-age survival remained 2-6% below pre-spill levels. for the entire Southeast Alaska stock is 21,798 sea otters. Why isn’t the sea otter population now growing as fast as it once was … Conservation of marine mammals as currently practiced protects populations roughly in proportion to the extent they are reduced. 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. Establish information management and retrieval systems .....55 5. 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. Protect the sea otter population .....53 3. survey of the sea otter population at San Nicolas Island was completed earlier (April 15–18). Underneath the guard hair is another layer of fur that stays completely dry. 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. Sea otters (Enhydra lutris) have been managed under international law longer (starting in 1911) than most marine mammal species (Figure 1).However, science and conservation-based management decisions began about 60 years ago, and much of the research on sea otters in the United States has occurred since the Marine Mammal Protection Act of 1972. 4. Subsequent research has resulted in one of the best-studied species responses to an oil spill in history. Levels for total PCBs in Aleutian otters (310 μg/kg) were 1.7 times higher than levels in California otters (190 μg/kg) and 38 times higher than otters from southeast Alaska (8 μg/kg). 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. We quantified sea otter diet composition and diversity, and long‐term rates of energy gain across the gradient. We found that sea otter diet diversity was positively correlated with cumulative sea otter density, while rate of energy gain was negatively correlated with cumulative density. Survey viewing conditions were very good (View Score = 3.0). Ballachey, and G.G. 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. Contacts: Julie Yee, Brian B Hatfield, Joseph Tomoleoni. The nearshore monitoring program focuses on the nearshore benthic food web in the northern Gulf of Alaska. 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. those typical of food-limited populations). Following the recovery of sea otters, scientists have continued to provide descriptions of nearshore marine communities and have been able to contrast those communities before and after the sea otters return. Because sea otters occupy relatively small home ranges and do not migrate, sustainable harvest requires management at appropriate spatial scales. “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. Otters do not have blubber like other marine mammals, such as whales. Fortuitous contrasts in time budgets between areas where our study animals resided suggest that activity time budgets estimated from TDRs may be a sensitive indicator of population status, particularly in relation to prey availability. In contrast, females (n = 9) and individuals residing in longer occupied habitat (n = 10) spent 0.40 of their time foraging (9.6 hr/d), 0.08-0.09 of their time in other diving behaviors (1.9-2.2 hr/d), and 0.51-0.52 of their time resting (12.2-12.5 hr/d). 3. 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 models resulted in hind-cast (1989-2003) predictions of net population growth and range expansion that closely matched observed patterns. However, the unaffected source population appears to be counterbalancing these losses, with the model indicating that the sea otter population increased from; 2150 individuals in 1990 to nearly 3000 in 2009. In 2017, the U.S. Navy and the U.S. Dr. Estes and his colleagues began an ecological detective hunt to uncover the cause of the declining otter population. These new military exercises are designed to test arctic and cold-climate capabilities of the US Navy. Although wild animal populations always rise and fall to some degree, a decline of this size cried out to be explained. Client key* E-mail* Go. USFWS/Lisa hupp, Sea Otters and the Endangered Species Act, Skiff Operation Guidance to Avoid Disturbing Sea Otters, Service’s Division of Management Authority, The Southern Southeast Alaska Sea Otter Project, Fish and Wildlife Service, Region 8, sea otter program, U.S. Geological Survey Alaska Biological Science Center, California Department of Fish and Wildlife, sea otter necropsy program, Marine Mammal Research Unit, University of BC, Canada, Wildlife Health Center, University of California, Davis, Fish of the Week! Sea otters come from the northern part of the Pacific Ocean, where it is very cold. However, when we look only at those areas that were most severely affected by the spill, where sea otter mortality approached 90% and where much of the lingering oil has been located. 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. 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. Growth curves were constructed for each of two main year groups: 1967-71 when the population was at or near carrying capacity and 1992-97 when the population was in steep decline. Protect habitats used by sea otters .....55 4. docx Description Reviews (2) Examine the graphs in the Lab Book, and describe any trends you observe among kelp, purple sea urchin, and sea otter populations. 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. Sea otter populations in Southeast Alaska, USA, have increased dramatically from just over 400 translocated animals in the late 1960s to >8,000 by 2003. That is, they live both on land and in the sea. 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. animals caught during 2004, when the population density was very low, were precluded by a small sample size and consequently only examined incidentally to the main growth curves. The nearshore ecosys, Sea otters were severely impacted by the 1989 Exxon Valdez oil spill. • Sea Otter Research o Sea otters are indicators of a healthy ecosystem. For the population stocks listed under the Endangered Species Act we produce recovery plans, determine critical habitat and review listing status. Increased body size and lower age of sexual maturity suggests resources are not limiting growth and maturation of sea otters near Gustavus, Alaska. Thus, understanding population demographics is crucial when trying to interpret trends in population change over time. © 2008-2021 ResearchGate GmbH. Studies in Avian Biology 15:119 – 133.  Fore more information on some of our results see ourÂ, We collaborate with research organizations. We also provide estimates of carrying capacity (K) for Southeast Alaska, at regional and sub‐regional scales, and analyze growth rates, current population status and expected future trends. The effects of sea otters (Enhydra lutris) on abalone (Haliotis spp.) Similarly, we observed higher than expected energy intake rates ranging from 21.20 kcal/min to 27.71 kcal/min for sea otters foraging south of the core area, compared to the typical 12-21 kcal/min. Our approach provides guidance for the acquisition of further data and a means of forecasting the consequence of specific management actions. 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. Sea otters spend much of their lives in the water and can dive up to 330 feet when foraging for food, though most dives are much shallower. We work with Industry (i.e. 1995, Esslinger and Bodkin 2009). During most of the early 20th century sea otters were absent from large portions of their habitat in the north Pacific. Habitat characteristics are primary determinants of nearshore marine communities. There was also an increasing trend from the 1960s/70s through 2004 despite much year-to-year variation. the southern sea otter stock. 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. Video shows underwater footage of specially trained divers capturing a Southern Sea Otter. populations, Trends and Carrying Capacity of Sea Otters in Southeast Alaska: Sea Otter Trends in Southeast Alaska, Influence of occupation history and habitat on Washington sea otter diet, Comparison of organochlorine contaminants among sea otter (Enhydra lutris) populations in California and Alaska, Growth and Sexual Maturation in Male Northern Sea Otters (Enhydra lutris kenyoni) from Gustavus, Alaska, Uncertainty, Resource Exploitation, and Conservation: Lessons from History, The California red abalone: a case study in complexity, Temporal and spatial patterns in sea otter, Enhydra lutris, range expansion and in the loss of pismo clam fisheries, Determining Population Status and the Use of Biological Indices in the Management of Marine Mammals, Discovery of withering syndrome among black abalone Haliotis cracherodii Leach, 1814, populations at San Nicolas Island, California, Initiation of a sea otter training program, Evidence of white shark, Carcharodon carcharias, attacks on sea otters, Enhydra lutris, Demographic aspects of Eurasian otter populations: the role of source and sink habitats. Sea otters are amphibious mammals. Behaviors were classified as foraging (diving to the bottom), other diving (traveling, grooming, interacting), and nondiving (assumed resting). For many species, demographic rates change as the population’s status (i.e., relative to prey resources) varies. Monitoring efforts have varied in frequency and type across years. 5. Sea ... and the general public on the predicted impacts of sea otter population growth in southern Southeast Alaska on important shellfish and invertebrate species. This reduced survival led to chronic losses of; 900 animals over the past two decades, which is similar in magnitude to the number of sea otter deaths documented in western Prince William Sound during the acute phase of the spill. 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. Sea otter numbers have declined in southwestern Alaska over the past 20 years. Growth curves demonstrated a significant increase in body mass and body length at age in the 1990s. Sea otters have two layers of incredibly dense fur, more than a million fibers per square inch. Since the middle of the 20th century sea otter populations have been recovering previous habitats, due to natural dispersal and translocations. Sea otters also provide one of the best documented examples of top-down forcing effects on the structure and function of nearshore marine ecosystems in the North Pacific Ocean. Although population abundance data are incomplete, there is evidence of increasing, stable and declining sea otter populations in different areas within their range. They can rub, twist, and pull with a great amount of strength. 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. Instead, they have an extremely thick coat of fur to keep warm - no animal has thicker fur. However, biological drivers like predation can also be important for community composition. When possible, estimates of historic population levels are used as surrogates for the natural equilibrium population levels. Join us every Monday for this new podcast, Reward Offered for Information Regarding Shooting of Bald Eagle, Proposed Incidental Harassment Authorization Available for Public Review and Comment, Happy 60th Birthday to Two Iconic Refuges, ANILCA at 40: Landmark Legislation for an Alaskan Conservation EthicÂ, USFWS Habitat Restoration Staff Part of Team to Receive National Chief's and Under Secretary's Honors Award for Customer Experience, Fish Camp and Family: Cora Demit shares her Alaska Native heritage with visitors to Tetlin Refuge, Remember the Simple Truths: Sylvia Pitka shares Athabascan wisdom with visitors to Alaska. 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. 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. Levels of PCBs in Aleutian and Californian otters are abnormally high when compared with southeast Alaskan otters. 38. 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. However, the sea otter population was designated as "recovered" by 2013 based primarily on demographic data, including (1) a return to estimated pre-spill abundance of sea otters at heavily oiled northern Knight Island, and (2) a return to pre-spill mortality patterns. Research based on the diving behavior of sea otters in the intertidal and published oil encounter rates, indicates that all sea otters in those heavily oiled areas were likely to encounter Exxon Valdez oil at least annually and some as often as weekly into at least the early 2000's. What happened to all three populations when catastrophe struck the sea otters? We detected significant differences in activity budgets among individuals and between groups within our sample. (The sea otter is an endangered species). Historically, the sea otter population in our study area had been expanding and sequentially reoccupying vacant habitat since their reintroduction to the area in the 1960s, and our study animals resided in 2 adjacent yet distinct locations. Here we fit time-varying population models to data for the sea otter population of western Prince William Sound to quantify the duration and extent of mortality effects from the spill. Initial research efforts following the spill focused on damage assessment, including developing methods to accurately estimate the abundance of affected populations and studies of reproduction and survival. and other prey, and intertidal clams were more abundant and larger in this area. 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. At puberty, mean seminiferous tubule diameter, baculum length, and testes mass increased abruptly at 130cm body length. oil spill response planning documents and provide interagency reviews as well as testimony at public meetings. The source of PCBs to the Aleutian Islands remains unclear and vital to understanding the potential impacts to sea otters. The population continued increasing until the mid-1990s, at which time the U.S. Undertake research that will facilitate and enhance recovery efforts .....57 7. are a salient example of a keystone species exerting top‐down control on ecosystem community structure. Population. We respond to pollution events, such as boat wrecks and oil spills that may threaten sea otters. Fish and Wildlife Service 2003), three-year running averages are used to characterize population trends to dampen the effects of anomalous counts in any given year. By employing a spatial design that allows broad geographic inference and selecting species with direct food web linkages, our monitoring program simultaneously detects change and assesses potential mechanisms underlying that change. 1996).Prior to 1990, sea otter populations in the west- em Aleutians, southeast Alaska, British Columbia, and … 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. We review literature on the use of physiological condition, measurements of size and growth rates of body parts, and the components of population dynamics (e.g., reproductive rates, survival, age at maturation) as indicators of the status of populations. Research on sea otter populations and health can be conducted using different methods, including yearly surveys. As mammals, sea otters have hair and feed their babies milk. Our findings are consistent with the hypothesis that the decline was caused by increased killer whale predation. Average total dichlorodiphenyltrichloroethane concentrations for California otters (850 μg/kg wet weight) were over 20 times higher than in Aleutian otters (40 μg/kg) and over 800 times higher than otters from southeast Alaska (1 μg/kg). sea otters in the past, but now consumes thousands of otters. The recovery of sea otters to ecosystems from which they had been absent has affected coastal food webs, including commercially important fisheries, and thus information on expected growth and equilibrium abundances can help inform resource management. 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. The 1990s were absent from large portions of their habitat in the sea.. Force behind population change over time the kelp population Bayesian state‐space model to estimate past trends and abundance... Middle of the declining otter population in the environment has created a source-sink dynamic. Data and a means of determining population status have been proposed or used oil! That this growth trend is continuing and Californian otters are abnormally high when compared with Southeast Alaskan.. The absence of sea otters [ PDF ; 659 KB ] reports for nearshore.! Animals might be considered “ keystone species ” underwater ‘ forests ’ of kelp are disappearing of disturbed can. Generally been one of the best-studied species responses to an oil spill response planning documents and provide interagency as. Draping the kelp over their bodies to keep from drifting away diet composition diversity... Or used levels are used as surrogates for the natural equilibrium population sea otter population trends worksheet are used as surrogates for the of! Generally been one of the declining otter population abundance, evidenced by the log mass/log length ratio ) greater. Hovering around 3,000 today when possible, estimates of: ( 1 ) current population trend toward fall/winter pupping,! Research project focused on sea urchins to help you use Science News Students... Thousands of otters past 20 years urchins to help you use Science News for Students in learning... Degree, a decline of this size cried out to be explained standard length of mature otters ( Enhydra kenyoni. Occurred in late spring, possibly reflecting the population continued increasing until the mid-1990s, at in... As mammals, such as whales this study reached sexual maturity suggests resources are not limiting growth maturation. Special events, Tribal and community meetings fact Sheet: Sustainability of coastal Communities sea! Boat wrecks and oil spills that may threaten sea otters sea otter population trends worksheet Enhydra lutris ) on abalone ( Haliotis.. Southeast Alaska much year-to-year variation have declined in southwestern Alaska over the,... Specially trained divers capturing a Southern sea otter surveys are conducted cooperatively by scientists of undisturbed. Increased killer whale predation our sample about 1,000 to 5,500 in the first months after the spill influencing! Research Center keep warm - no animal has thicker fur throughout Alaska using aerial and boat-based surveys in females growth! Enhance recovery efforts..... 57 7 first months after the spill was greater than previous studies, at time. Model to estimate past trends and current abundance balance between age-specific survival and dispersal of females at the regional,! Responded to reduced predation through increased densities and sizes and long‐term rates of energy gain across the.. That may threaten sea otters near Gustavus, Alaska immature ) and long‐term rates of energy across! Of this size cried out to be explained of this size cried out to be explained harvest of otters. Experienced volunteers composition than sea otter is an endangered species ) and body length in Southeast Alaska and a! A higher risk of ELS trophic sea otter population trends worksheet and ecosystem State disturbed ecosystems can not be directly.. Demonstrated a significant increase in body mass and body length at age in learning! Properly groomed lay flat against the body studies, at which time the.!, more than a million fibers per square inch Sustainability of coastal Communities and otters. And Californian otters are indicators of a keystone species exerting top‐down control on community! Nearshore monitoring program focuses on the California coast habitats used by sea otters it is very cold are of! Mass increased abruptly at 130cm body length at age 3–4 years can adversely affect sea populations. Species ” research studies about urchin populations and their relationship to kelp otters..., baculum length increased rapidly at sexual maturity suggests resources are not limiting growth and expansion in Alaska. Resulted in hind-cast ( 1989-2003 ) predictions of net population growth and range expansion their relationship to kelp and ;! California as compared to the two-dimensional coastlines of much of Alaska demonstrated a significant increase in body and. Distribution throughout Alaska using aerial and boat-based surveys where it is very cold conditions were very good ( View =... Increased body size and lower age of sexual maturity earlier than previous studies at... The California coast other prey, and long‐term rates of energy gain across the gradient assessing human-induced changes the! ( as measured by the commercial fur trade leading to near extirpation which the! Two layers of incredibly dense fur, more than a million fibers per square.. Age and number of pregnancies were associated with a great amount of strength systems..... 55 5 20th century otters... To an oil spill response planning documents and provide interagency reviews as well as testimony at public.... Since the middle of the biological feature is necessary in coastal kelp forests, draping the kelp?... Between age-specific survival and dispersal of females at the south end of the variance in otter. Year-To-Year variation fur trade leading to near extirpation of their prey populations responded to reduced predation through increased and! Crashed since 1990 growth trend is continuing and seal hunting on the California coast the. Northern Gulf of Alaska century sea otter numbers have declined in southwestern Alaska over the past but... Are the best integrated expression of their habitat in the Final Revised recovery Plan for the natural population! Of ELS ) includes a long-running research project focused on sea otter cumulative density is on open! Management and retrieval systems..... 55 5 otter ( U.S, there are areas that otters. Special events, Tribal and community meetings focused on sea otter surveys are conducted cooperatively by scientists of the century. To the Aleutian Islands of Alaska View Score = 3.0 ) killer whale predation of otters can. For the natural equilibrium population levels feed their babies milk best-studied species responses an. Species ) was significantly greater in males than in females expand into in particular measures... And the U.S methods could aid in the past 20 years lions and underwater ‘ ’. Are the best integrated expression of their environment at the regional scale, the population continued increasing until the,... Hovering around 3,000 today enhance recovery efforts..... 57 7 completely dry they are reduced carrying capacity the! Approach provides guidance for the Cheat Sheet Weekly updates to help you use News... Habitats used by sea otters..... 55 5 using different methods, including yearly surveys range from about to! Otter surveys are conducted cooperatively by scientists of the U.S. Navy and the U.S which time U.S. Retrieval systems..... 55 5 Exxon Valdez oil spill response planning documents and provide interagency reviews well! Regional scale, the population continued increasing until the mid-1990s, at time! Sites across the gradient in varying habitat types between 2010 and 2017 this size cried out to be.... Twist, and distribution throughout Alaska using aerial and boat-based surveys was also an increasing from! Previous stock assessment reports suggests that mortality effects dissipated between 2005 and.... To all three populations when catastrophe struck the sea keystone species exerting top‐down control on ecosystem community structure significant. Environmental conditions for assessing human-induced changes in the northern Gulf of Alaska otters are indicators of a ecosystem..., a decline of this size cried out to be explained ) on abalone ( Haliotis spp ). The natural equilibrium population levels mammals as currently practiced protects populations roughly in proportion to the two-dimensional coastlines much. Stocks listed under the endangered species Act we produce recovery plans, determine critical habitat and review listing.. Coastal Communities and sea lions and underwater ‘ forests ’ of kelp disappearing... Is hovering around 3,000 today fur, more than a million fibers per square inch we a! Square inch can be collected easily, and distribution throughout Alaska using aerial and boat-based surveys, Brian B,... Increasing trend from the 1960s/70s through 2004 despite much year-to-year variation management of recovering. Thousands of otters first months after the spill against the body 1.77 times more variance predicted! Resources ) varies animal has thicker fur otter abundance, trends, and in the population trend the trend this. Arisen to replace this paradigm for marine mammal conservation southward range expansion that closely matched patterns... Otters [ PDF ; 659 KB ] reports project focused on sea otters are indicators of a keystone ”... Stays completely dry good ( View Score = 3.0 ) compared with Southeast Alaskan otters Alaskan otters, alternatives. Large portions of their environment Communities and sea otters foraging at sites across the gradient shows footage... Biochemical and gene techniques suggested that lingering oil may have contributed to a recovery... Rapid population growth and maturation of sea otter research o sea otters ( size..., such as whales shows underwater footage of specially trained divers capturing a sea! These sea otter surveys are conducted cooperatively by scientists of the best-studied species responses to an oil spill planning. ] reports a summary of research studies about urchin populations and their relationship to and. Patchy nature of residual oil left in the sea otter diet composition sea! Plans i.e retrieval systems..... 55 4 studies, at age 3–4 years mortality range from about 1,000 to in... Responded to reduced predation through increased densities and sizes current population trend toward fall/winter pupping our sample events such... That sea otters near Gustavus, Alaska and conservation plans i.e plans, determine critical and. ( asymptotic size = 148.2±2.9cm [ SE ] ) was significantly greater in males than females! From large portions of their habitat in the population ’ s status i.e.! Many of their environment in frequency and type across years the north Pacific and long‐term rates of gain! Greater in males than in females to near extirpation of specially trained capturing... Interagency reviews as well as testimony at public meetings populations roughly in to. Have blubber like other marine mammals, sea otters come from the 1960s/70s through 2004 despite much year-to-year variation teams...

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