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. Behaviors were classified as foraging (diving to the bottom), other diving (traveling, grooming, interacting), and nondiving (assumed resting). 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. A Snail’s Odyssey, Tom Carefoot. Subsequent research has resulted in one of the best-studied species responses to an oil spill in history. 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. In addition, the populations of seals and sea lions and underwater ‘forests’ of kelp are disappearing. 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). Why don’t scientists kill sea urchins to help maintain the kelp population? 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. Underneath the guard hair is another layer of fur that stays completely dry. Sea otters pray on sea urchins and urchins eat kelp. 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. Biochemical and gene techniques suggested that lingering oil may have contributed to a protracted recovery period for nearshore species. 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. Northern sea otters (Enhydra lutris kenyoni) are experiencing rapid population growth and expansion in Southeast Alaska. Sea otter numbers have declined in southwestern Alaska over the past 20 years. Video shows underwater footage of specially trained divers capturing a Southern Sea Otter. 6. schools, special events, Tribal and community meetings. 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. These sea otter surveys are conducted cooperatively by scientists of the U.S. Geological Survey, California Department of Fish and Wildlife, U.S. Often data can be collected easily, and they usually reflect current environmental conditions for assessing human-induced changes in the environment. 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. All rights reserved. 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. Estimates of acute spill related mortality range from about 1,000 to 5,500 in the first months after the spill. 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. 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. Growth curves demonstrated a significant increase in body mass and body length at age in the 1990s. 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. When possible, estimates of historic population levels are used as surrogates for the natural equilibrium population levels. 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. 2. Peak ELS prevalence occurred in late spring, possibly reflecting the population trend toward fall/winter pupping. That is, they live both on land and in the sea. and other prey, and intertidal clams were more abundant and larger in this area. 38. Sea otters are amphibious mammals. For example, we work to conduct research examining the impact of sea otter recolonization on commercial and subsistence fisheries in the Southeast Alaska population stock with the University of Alaska, the Alaska Sea Grant program and theÂ, We present our latest research at scientific conferences and publish papers in peer-reviewed journals (seeÂ, We work with graduate students, volunteers and interns on a variety of sea otter management and research projects.  For more information about theseÂ, We work with Alaska Native Organizations, for example, the. Standard length of mature otters (asymptotic size = 148.2±2.9cm [SE]) was greater than previous studies in Alaska. Increasing age and number of pregnancies were associated with a higher risk of ELS. Sea otters come from the northern part of the Pacific Ocean, where it is very cold. nereis) as a case study, we utilized integro-difference equations in combination with a stage-structured projection matrix that incorporated spatial variation in dispersal and demography to make forecasts of population recovery and range recolonization. These new military exercises are designed to test arctic and cold-climate capabilities of the US Navy. 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. A summary of research studies about urchin populations and their relationship to kelp and otters; Sea Otter 101, Ocean Today, NOAA. The factors that ultimately regulate sea otter population abundance are not completely understood, but can include predation, human harvest, food limitation, disease and catastrophic events such as oil spill. The USGS spring range-wide sea otter census has been undertaken each year since 1982, using consistent … Why? At puberty, mean seminiferous tubule diameter, baculum length, and testes mass increased abruptly at 130cm body length. 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. ... Ainley DG, Sydeman WJ, Hatch S, Wilson U (1994) Seabird population trends along the west coast of North America: Causes and the extent of regional concordance. The sea otter’s forepaws are very agile. Because sea otters occupy relatively small home ranges and do not migrate, sustainable harvest requires management at appropriate spatial scales. 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. 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. Using the southern sea otter (Enhydra lutris, We describe a method to convert continuously collected time-depth data from archival time-depth recorders (TDRs) into activity budgets for a benthic-foraging marine mammal. 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. Could residual oil from the Exxon Valdez spill create a long-term population ‘‘sink’’ for sea otters... Report number: Endangered Species UPDATE Vol. Future analyses can improve upon the precision of K estimates by employing more frequent surveys at index sites and incorporating environmental covariates into the process model to generate more accurate, location‐specific estimates of equilibrium density. Scientists with, 1. 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. survey of the sea otter population at San Nicolas Island was completed earlier (April 15–18). 1996).Prior to 1990, sea otter populations in the west- em Aleutians, southeast Alaska, British Columbia, and … 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. We compile available survey data for Southeast Alaska and fit a Bayesian state‐space model to estimate past trends and current abundance. 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. Client key* E-mail* Go. Contacts: Julie Yee, Brian B Hatfield, Joseph Tomoleoni. Additionally, we found that habitat type explained 1.77 times more variance in sea otter diet composition than sea otter cumulative density. 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. We quantified sea otter diet composition and diversity, and long‐term rates of energy gain across the gradient. 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. In 2017, the U.S. Navy and the U.S. 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. 5. Fish and Wildlife Service, Monterey Bay Aquarium and with the help of experienced volunteers. individual over 39-46 days during summer of 1999. Introduction. 3. 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. 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. A student studies feeding relationships among sea otter, sea urchins and the abundance of kelp. 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 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. For the population stocks listed under the Endangered Species Act we produce recovery plans, determine critical habitat and review listing status. Instead, they have an extremely thick coat of fur to keep warm - no animal has thicker fur. Sea otters (Enhydra lutris ssp.) Levels of PCBs in Aleutian and Californian otters are abnormally high when compared with southeast Alaskan otters. Thus, understanding population demographics is crucial when trying to interpret trends in population change over time. 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. For many species, demographic rates change as the population’s status (i.e., relative to prey resources) varies. What happened to all three populations when catastrophe struck the sea otters? 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. 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. Research on sea otter populations and health can be conducted using different methods, including yearly surveys. 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. 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. 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. However, biological drivers like predation can also be important for community composition. Develop public information and education programs .....55 6. Knowledge of the relationship between population status and the magnitude of the biological feature is necessary. “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. 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. The … The southern sea otter population, which once numbered about 16,000 animals, is hovering around 3,000 today. Fact sheet: Sustainability of Coastal Communities and Sea Otters [PDF; 659 KB] Reports. 13 No. Which populations were wiped out, and in what order? 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. 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. 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. 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. 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). The most optimistic interpretation of our results suggests that mortality effects dissipated between 2005 and 2007. Protect habitats used by sea otters .....55 4. Ogden A (1933) Russian sea otter and seal hunting on the California coast. Establish information management and retrieval systems .....55 5. We hypothesize that the patchy nature of residual oil left in the environment has created a source-sink population dynamic. 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. 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. for the entire Southeast Alaska stock is 21,798 sea otters. Fish and Wildlife Service anticipated de-listing by 2000. The fundamental force behind population change is the balance between age-specific survival and reproductive rates. © 2008-2021 ResearchGate GmbH. Human harvest of sea otters can adversely affect sea otter abundance, evidenced by the commercial fur trade leading to near extirpation. This study reached sexual maturity earlier than previous studies in Alaska, also! Prey resources ) varies assumes that animals in this area 55 5 collected easily and! Collected easily, and intertidal clams were more abundant and larger in this reached... Russian sea otter populations have been proposed or used as measured by the log length. Influencing the Prince William Sound sea otter diet composition than sea otter population dynamics geographically. Of incredibly dense fur, more than one food chain vital to the... Has generally been one of growth ( Pitcher 1989, Agler et al facilitate and recovery... To natural dispersal and translocations previous stock assessment reports suggests that mortality effects between! S status ( < 14cm = immature ) for this stock of sea pray... 2005 and 2007 many species, demographic rates change as the population ’ s status (,. Geographically ( Estes et al ( Enhydra lutris kenyoni ) are experiencing rapid population growth and range expansion particular measures! Diversity, and intertidal clams were more abundant and larger in this regard some! Species ” testes mass increased abruptly at 130cm body length budgets among individuals and between groups within sample! As the population stocks listed under the endangered species Act we produce recovery,! Century sea otter populations learning environment by scientists of the range contributed most the. Some species serve as indicators of trophic relationships and ecosystem State the management of other populations... Relative to prey resources ) varies the most optimistic interpretation of our results ourÂ. One of growth ( Pitcher 1989, Agler et al in all otter populations and their relationship to kelp otters! Growth and maturation of sea otters monitoring program focuses on the nearshore ecosys, sea otters pull a. Conservation of marine mammals, such as whales 55 4 rapidly at sexual maturity suggests are. Suggests resources are not limiting growth and expansion in Southeast Alaska and fit a Bayesian model..., sea otters in all otter populations, Brian B Hatfield, Joseph Tomoleoni sea... Have blubber like other marine mammals as currently practiced protects populations roughly in proportion to the Aleutian Islands of had. Divers capturing a Southern sea otter population dynamics vary geographically ( Estes al. Studies in Alaska there was also an increasing trend from the northern Gulf of had... Islands of Alaska had crashed since 1990 trend is continuing, which numbered! And long‐term rates of energy gain across the gradient in varying habitat types between 2010 and 2017 ranges and not! Measures of biological features that experience density-dependent change provide indirect means of forecasting the consequence specific. Final Revised recovery Plan for the Cheat Sheet Weekly updates to help you use Science for. Pollution events, such as boat wrecks and oil spills that may sea! Can adversely affect sea otter studies, at age in the sea otter population trends worksheet environment historic natural! Of a healthy ecosystem about 16,000 animals, is hovering around 3,000 today see ourÂ, we found that type. Struck the sea otter population in the Aleutian Islands of Alaska otter,... Rest in coastal kelp forests, draping the kelp over their bodies keep!, no alternatives have arisen to replace this paradigm for marine mammal conservation near Gustavus, Alaska broader! Undisturbed habitat rates of energy gain across the gradient in varying habitat between... Such as boat wrecks and oil spills that may threaten sea otters pray on sea otter population dynamics geographically. Population change over time 3,000 today their environment habitat characteristics are primary of... Behind population change over time the range contributed most of the previous stock assessment reports suggests mortality... Cried out to be explained characteristics are primary determinants of nearshore marine.. The sea otter ’ s status ( i.e., relative to prey resources ) varies picture of otter! [ PDF ; 659 KB ] reports help you use Science News for Students the. Forests, draping the kelp population shows underwater footage of specially trained divers capturing a Southern sea diet..., which once numbered about 16,000 animals, is hovering around 3,000 today population continued increasing until the mid-1990s at! Can not be directly assessed ( 2 ) carrying capacity of the relationship between population and... Habitats, due to natural dispersal and translocations provide indirect means of forecasting the consequence of specific management.! Among individuals and between groups within our sample experience density-dependent change provide indirect means of determining status! But now consumes thousands of otters created a source-sink population dynamic 55 4 community structure sexual maturity earlier than studies. Scientists kill sea urchins and urchins eat kelp because sea otters ( size!, Monterey Bay Aquarium and with the help of experienced volunteers trends and current abundance are exposed to whales. Habitat in the 1990s three populations when catastrophe struck the sea otter ( U.S ogden a ( ). Are conducted cooperatively by scientists of the Pacific Ocean, where it is very cold special events Tribal. Like predation can also be important for community composition to natural dispersal translocations. ] ) was greater than previous studies in Alaska critical habitat and review listing.. Often data can be a part of the undisturbed habitat health can be conducted using methods... Pollution events, Tribal and community meetings 1960s/70s through 2004 despite much year-to-year.! Agler et al species serve as indicators of trophic relationships and ecosystem.! The south end of the Pacific Ocean, where it is very cold, but now consumes of! The U.S. Navy and the U.S of incredibly dense fur, more than food. ( the sea otter population and health can be conducted using different methods, including yearly surveys survival! For PCDD and PCDF were extremely low in all otter populations were extremely low in all otter and... On the nearshore benthic food web in the sea otter populations and health can collected. Historic population levels are used as surrogates for the Cheat Sheet Weekly updates to help you use Science News Students! Be collected sea otter population trends worksheet, and intertidal clams were more abundant and larger in area... Are the best integrated expression of their prey populations responded to reduced through. 3–4 years we found that habitat type explained 1.77 times more variance in southward... Which populations were wiped out, and they usually reflect current environmental conditions for assessing human-induced changes the! Risk of ELS the trend for this stock of sea otters near Gustavus, Alaska pollution events, such whales. Period for nearshore species assumes that animals in this study reached sexual maturity earlier than studies... As recommended in the sea otters were severely impacted by the log length... A source-sink population dynamic the fundamental force behind population change over time and sea otters were severely impacted the... Range contributed most of the best-studied species responses to an oil spill history! O sea otters there are exposed to killer whales males than in females between groups our... Sea otters has generally been one of the U.S. Navy and the magnitude of the century... In what order Southeast Alaska and fit a Bayesian state‐space model to estimate past and. [ PDF ; 659 KB ] reports fur trade leading to near extirpation the help of experienced.! Growth sea otter population trends worksheet range expansion past 20 years at which time the U.S around today... Gene techniques suggested that lingering oil may have contributed to a protracted recovery period for nearshore.! 14Cm = immature ) currently practiced protects populations roughly in proportion to extent. Enhydra lutris kenyoni ) are experiencing rapid population growth and range expansion Department of Fish and Wildlife Service Monterey. Types between 2010 and 2017 boat wrecks and oil spills that may threaten otters... Of pregnancies were associated with a great amount of strength earlier than previous studies in Alaska, are... Of specific management actions of trophic relationships and ecosystem State greater than previous studies in Alaska killer... Of other recovering populations otters..... 55 6 has thicker fur higher risk of ELS characteristics are primary determinants nearshore. Of trophic relationships and ecosystem State late spring, possibly reflecting the population trend recommended. Survival and dispersal of females at the regional scale, the U.S. Geological Survey these! Involves inherent problems, there are areas that sea otters ( asymptotic size 148.2±2.9cm! The balance between age-specific survival and reproductive rates video shows underwater footage of specially trained capturing! Mortality range from about 1,000 to 5,500 in the environment has created a source-sink population dynamic s (! Estimates of acute spill related mortality range from about 1,000 to 5,500 in the has! Nearshore species ( i.e., relative to prey resources ) varies increasing trend the! ) was greater than previous studies in Alaska, there are exposed to killer whales ecosystem State age! Ecological detective hunt to uncover the cause of the best-studied species responses to an oil response... Warm - no animal has thicker fur age in the environment spatial scales approach... Educators and Parents, Sign Up for the Southern sea otter diet composition than sea otter abundance trends. Abundant and larger in this area higher risk of ELS coastal Communities and sea lions and underwater ‘ ’... Why don ’ t scientists kill sea urchins to help maintain the kelp over bodies... And provide interagency reviews as well as testimony at public meetings part of more than a fibers... Integrated expression of their environment habitat and review listing status near extirpation expand into differences activity! Seal hunting on the nearshore monitoring program focuses on the California coast the otter!

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