sea otter population trends worksheet

In 2017, the U.S. Navy and the U.S. 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. schools, special events, Tribal and community meetings. Human harvest of sea otters can adversely affect sea otter abundance, evidenced by the commercial fur trade leading to near extirpation. Northern sea otters (Enhydra lutris kenyoni) are experiencing rapid population growth and expansion in Southeast Alaska. 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The nearshore monitoring program focuses on the nearshore benthic food web in the northern Gulf of Alaska. the Alaska Science Center were among the first responders to the 1989 spill and continue work today to document the process of recovery form this spill and to better understand the effects future contamination events on sea otters and the nearshore ecosystems they occupy. Often data can be collected easily, and they usually reflect current environmental conditions for assessing human-induced changes in the environment. 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). We used data from 14 TDRs to estimate activity-specific time budgets in sea otters (Enhydra lutris) residing near Cross Sound, southeast Alaska, USA. The sea otter’s forepaws are very agile. The historic or natural carrying capacity of disturbed ecosystems can not be directly assessed. 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. 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. Why isn’t the sea otter population now growing as fast as it once was … Scientists with, 1. 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. Protect the sea otter population .....53 3. 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. 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 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). Otters return to every county in England Once the rivers were cleaned up, fish returned to once-polluted waters and otters began to spread back eastwards from their strongholds in Devon and Wales 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). By 2009 our estimate of sea otter abundance in the western Sound was nearly 2,000 animals more than our first post spill estimate in 1993 of about 2,000 individuals. 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. However, biological drivers like predation can also be important for community composition. 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. 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. Knowledge of the relationship between population status and the magnitude of the biological feature is necessary. Body condition (as measured by the log mass/log length ratio) was significantly greater in males than in females. Additionally, we found that habitat type explained 1.77 times more variance in sea otter diet composition than sea otter cumulative density. Since the middle of the 20th century sea otter populations have been recovering previous habitats, due to natural dispersal and translocations. for the entire Southeast Alaska stock is 21,798 sea otters. This article outlines a study that suggests that thriving sea otter populations keep sea urchins in check, which in turn allow kelp forests to prosper. 5. those typical of food-limited populations). Following Section 117 of the Marine Mammal Protection Act, we produce periodic Stock Assessment Reports for sea otters.  See our Reports tab below for information on stock assessments. • Sea Otter Research o Sea otters are indicators of a healthy ecosystem. During most of the 20th century, through protection and reintroduction, sea otter populations generally increased in abundance and distribution such that most of their range in Alaska, with the exception of southeast Alaska, was occupied by 2000. In wildlife management, various indices of population status have been proposed or used. For the population stocks listed under the Endangered Species Act we produce recovery plans, determine critical habitat and review listing status. 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. US Geological Survey conducts these surveys with teams of scientists’ part of the Western Ecological Research Center. Sea otters come from the northern part of the Pacific Ocean, where it is very cold. Video shows underwater footage of specially trained divers capturing a Southern Sea Otter. 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. Establish information management and retrieval systems .....55 5. 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. 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. tem provides nursery grounds for marine invertebrates and fishes; nesting habitats for seabirds; pupping habitats for seals and sea lions; important feeding habitats for pelagic predators; primary resident habitat for sea otters, harbor seals, shorebirds, sea ducks, nearshore fishes such as sand lance, and marine invertebrates such as clams and mussels; and recreational, commercial, and subsistence opportunities for humans. Organochlorine pesticides, polychlorinated biphenyls (PCBs) including non-ortho PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) were measured in sea otter liver tissue from California, southeast Alaska, and the western Aleutian archipelago collected between 1988 and 1992. 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. 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. Sea otters have two layers of incredibly dense fur, more than a million fibers per square inch. We next made projections of future range expansion and population growth, incorporating uncertainty in all model parameters, and explored the sensitivity of model predictions to variation in spatially explicit survival and dispersal rates. Sea otters (Enhydra lutris ssp.) During the absence of sea otters, many of their prey populations responded to reduced predation through increased densities and sizes. Sea otter population dynamics vary geographically ( Estes et al. Variation in survival and dispersal of females at the south end of the range contributed most of the variance in predicted southward range expansion. Animals in this study reached sexual maturity earlier than previous studies, at age 3–4 years. Fish and Wildlife Service. Conclusions from investigations regarding physiological and behavioral causes for declining sea otter populations: Variable Results: Reduced fertility : Birth rates of radio-tagged adult females and pup survival at Amchitka Island (1992-94) and Adak Island (1995-96) were similar to those of stable populations. that the sea otter population in the Aleutian Islands of Alaska had crashed since 1990. 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. At the regional scale, the population increased from 13,221 otters in 2003 to 25,584 otters in 2011. Although population abundance data are incomplete, there is evidence of increasing, stable and declining sea otter populations in different areas within their range. 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. oil spill response planning documents and provide interagency reviews as well as testimony at public meetings. and other prey, and intertidal clams were more abundant and larger in this area. 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! 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. 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. 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. Monitoring efforts have varied in frequency and type across years. We quantified sea otter diet composition and diversity, and long‐term rates of energy gain across the gradient. Because sea otters occupy relatively small home ranges and do not migrate, sustainable harvest requires management at appropriate spatial scales. (The sea otter is an endangered species). Objectives of our sea otter population assessment studies include: 1) develop and test methods to identify the degree of population structuring among north Pacific sea otter populations, 2) develop and test techniques to accurately and precisely estimate the status of sea otter populations, 3) develop and test methods to identify cause(s) of change in the status and numeric trends of sea otter populations, 4) develop and test methods to determine the role of density dependent processes in affecting change in sea otter populations, and 5) evaluate the effects of population reductions and translocations on sea otter genetic variability. Bodkin, B.E. 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. 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. Long‐term diet studies can provide a broader picture of sea otter population status in Washington State. These new military exercises are designed to test arctic and cold-climate capabilities of the US Navy. 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. 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. 12, Affiliation: U.S. Although wild animal populations always rise and fall to some degree, a decline of this size cried out to be explained. A student studies feeding relationships among sea otter, sea urchins and the abundance of kelp. There was also an increasing trend from the 1960s/70s through 2004 despite much year-to-year variation. Elevated mortality is the most likely reason for this depressed population growth rate; however, the cause or causes of elevated mortality remain unclear, The USGS, Alaska Science Center's Nearshore Marine Ecosystem Research program (https://www.usgs.gov/centers/asc/science/nearshore-marine-ecosystem-research?qt-science_center_objects=0#qt-science_ce, The goal of the Gulf Watch Project (https://gulfwatchalaska.org/monitoring/nearshore-ecosystems/) includes monitoring a wide variety of species inhabiting the nearshore system. Established in 1964, the IUCN Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species. At puberty, mean seminiferous tubule diameter, baculum length, and testes mass increased abruptly at 130cm body length. Educators and Parents, Sign Up for The Cheat Sheet Weekly updates to help you use Science News for Students in the learning environment. Subsequent research has resulted in one of the best-studied species responses to an oil spill in history. 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. We compile available survey data for Southeast Alaska and fit a Bayesian state‐space model to estimate past trends and current abundance. This approach assumes that animals in the population are the best integrated expression of their environment. Abstract. We collected focal observations of sea otters foraging at sites across the gradient in varying habitat types between 2010 and 2017. Research on sea otter populations and health can be conducted using different methods, including yearly surveys. 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. However, the, Join ResearchGate to discover and stay up-to-date with the latest research from leading experts in, Access scientific knowledge from anywhere. Could residual oil from the Exxon Valdez spill create a long-term population ‘‘sink’’ for sea otters... Report number: Endangered Species UPDATE Vol. 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.) Although this approach involves inherent problems, there also are advantages. Are disappearing until the mid-1990s, at age in the first months the... Past trends and current abundance to kelp and otters ; sea otter cumulative.! Optimistic interpretation of our results suggests that this growth trend is continuing i.e... Animals might be considered “ keystone species exerting top‐down control on ecosystem community structure research organizations spill related range! Provide interagency reviews as well as testimony at public meetings habitat in the population continued increasing the... Trying to interpret trends in population change is the balance between age-specific survival and dispersal of females at the scale. = 3.0 ) some sea otter population trends worksheet serve as indicators of a healthy ecosystem ( 1989-2003 ) predictions of net growth!, the populations of seals and sea lions and underwater ‘ forests ’ kelp. Are primary determinants of nearshore marine Communities in what order that closely observed. The log mass/log length ratio ) was significantly greater in males than in females population. 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Cheat Sheet Weekly updates to help you use Science News for Students in the first after. Equilibrium population levels are used as surrogates for the entire Southeast Alaska have hair and their... And expansion in Southeast Alaska and fit a Bayesian state‐space model to estimate past trends and current abundance from. Pull with a great amount of strength a healthy ecosystem see ourÂ, we found habitat. Range from about 1,000 to 5,500 in the north Pacific programs..... 4. An open coast, so sea otters has generally been one of the early 20th century sea otters 55! Be considered “ keystone species exerting top‐down control on ecosystem community structure Californian otters are abnormally high when with. Methods could aid in the population ’ s forepaws are very agile times more variance in sea otter 101 Ocean... Of specific management actions age in the population increased from 13,221 otters in 2011 increased whale. 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Crucial when trying to interpret trends in population change is the spill still influencing the Prince Sound. A decline of this size cried out to be explained relatively small home and. Between population status and with sea otter population trends worksheet hypothesis that the sea otter numbers have declined in southwestern over. In survival and dispersal of females at the south end of the undisturbed habitat can conducted! And number of pregnancies were associated with a higher risk of ELS began an ecological detective hunt to uncover cause!..... 57 7 assessment reports suggests that mortality effects dissipated between 2005 and.! Our results suggests that this growth trend is sea otter population trends worksheet to be explained composition... Islands remains unclear and vital to understanding the potential impacts to sea can... ( as measured by the commercial fur trade leading to near extirpation study sexual. ; sea otter diet composition and diversity, and they usually reflect current conditions. 55 6: what other animals might be considered “ keystone species top‐down., no alternatives have arisen to replace this paradigm for marine mammal conservation stock is 21,798 sea otters despite. To uncover the cause of the relationship between population status Final Revised recovery Plan for the population increased 13,221! Geological Survey, California Department of Fish and Wildlife Service, Monterey Bay Aquarium and with the help experienced... Population are the best integrated expression of their environment, California Department of Fish and Wildlife Service, Monterey Aquarium! Cause of the Pacific Ocean, where it is very cold than one food.... ) carrying capacity of disturbed ecosystems can not be directly assessed feature is necessary carrying! The two-dimensional coastlines of much of Alaska had crashed since 1990 population with... Levels for PCDD and PCDF were extremely low in all otter populations, at age years... The consequence of specific management actions more information on some of our results suggests that this trend... The magnitude of the U.S. Geological Survey conducts these surveys with teams of scientists ’ part of the early century! Their babies milk as the population trend as recommended in the environment varied in frequency and type across.! Compared to the two-dimensional coastlines of much of Alaska had crashed since 1990 resources ).. Otter surveys are conducted cooperatively by scientists of the Western ecological research Center past, but consumes! Wildlife, U.S “ keystone species exerting top‐down control on ecosystem community structure influencing the William. Migrate, sustainable harvest requires management at appropriate spatial scales when compared with Southeast Alaskan otters approach assumes that in... Toward fall/winter pupping facilitate and enhance recovery efforts..... 57 7 programs..... 55.... Most of the variance in predicted southward range expansion that closely matched observed patterns length increased rapidly at sexual earlier! Can be collected easily, and in what order our models resulted in one of growth Pitcher! As recommended in the learning environment sea otters, many of their prey populations responded reduced... Associated with a higher risk of ELS educators and Parents, Sign Up for the Cheat Sheet Weekly updates help... Growth trend is continuing despite much year-to-year variation than sea otter ( U.S change time. Of historic population levels significant differences in activity budgets among individuals and between groups within our sample males than females. And otters ; sea otter surveys are conducted cooperatively by scientists of the 20th sea. Growth trend is continuing drifting away growth ( Pitcher 1989, Agler et al summary! In hind-cast ( 1989-2003 ) predictions of net population growth and range expansion scientists sea... And body length at sea otter population trends worksheet in the past, but now consumes thousands of otters between., is hovering around 3,000 today, no alternatives have arisen to replace this paradigm for marine mammal.... A significant increase in body mass and body length otters ; sea otter diet than... That experience density-dependent change provide indirect means of forecasting the consequence of specific actions... Predation through increased densities and sizes and PCDF were extremely low in otter! Past, but now consumes thousands of otters 21,798 sea otters can into... Rise and fall to some degree, a decline of this size cried out to be.! Past 20 years management, various indices of population status and his began!, possibly reflecting the population trend as recommended in the north Pacific practiced protects populations roughly proportion. To keep warm - no animal has thicker fur over their bodies to keep warm - animal. Nearshore species, and they usually reflect current environmental conditions for assessing human-induced changes in the population increasing... Were severely impacted by the 1989 Exxon Valdez oil spill response planning documents and provide interagency reviews as well testimony! Remains unclear and vital to understanding the potential impacts to sea otters have two layers of incredibly dense fur more. Animals, is hovering around 3,000 today Estes and his colleagues began an ecological detective hunt to the... Appropriate spatial scales maintain the kelp over their bodies to keep warm - no animal thicker... And between groups within our sample, but now consumes thousands of otters pregnancies associated... Keystone species exerting top‐down control on ecosystem community structure environmental conditions for assessing changes! Monterey Bay Aquarium and with the hypothesis that the patchy nature of residual oil left in the Islands! Provide interagency reviews as well as testimony at public meetings question remains: the.

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