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The data represent hourly temperatures recorded at four permanent subtidal monitoring sites around San Nicolas Island, CA between November 2015 and October 2019. The temperatures were recorded by TidbiT (registered trademark) v2 model UTBI-001 (Onset Computer Corporation, Bourne, Massachusetts) archival temperature loggers attached at the sea floor. The loggers were deployed approximately 10-12 m deep at Nav Fac (12 m) on the north side of the island, at West End Urchin (11 m) on the southwest side, at east Dutch Harbor (11 m) on the south side, and at Daytona Beach (10 m) near the east end of the island.
The data consist of levels of organic pollutants found in the blue mussels (Mytelus trossulus) samples from 44 sites along the Aleutian archipelago and in Cross Sound in southeast Alaska. For each site, the percent lipid, percent water and the sum of the target organic compounds are reported. The compounds are PCBs (polychlorinated biphenyls), DDTs (dichlorodiphenyltrichloroethanes), HCHs (hexachlorocyclohexanes), chlordane, and HCB (hexachlorocyclobenzene).
The data consist of levels of organic pollutants found in the blood of sea otters captured from five areas in the western aleutian Islands and in Cross Sound in southeast Alaska. For each location, the sample size, and the median and range of values for each compound is provided. The compounds are PCBs (polychlorinated biphenyls), DDTs (dichlorodiphenyltrichloroethanes), HCHs (hexachlorocyclohexanes), chlordane, HCB (hexachlorocyclobenzene), and dieldrin.
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The GIS shapefile Extra limit counts of southern sea otters 2019 is a point layer representing the locations of sea otter sightings that fall outside the officially recognized range of the southern sea otter (Enhydra lutris nereis) in mainland California. These data were collected during the spring 2019 range-wide census. The USGS range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. Sea otter distribution in California (the mainland range) is considered to comprise a band of potential habitat stretching...
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The data represent 3 replicate measures of linear distance along 30 fixed transects on permanent subtidal monitoring sites around San Nicolas Island, CA. There were six sites, each of which had five 10-meter by 2-meter band transects on which a suite of kelps and macroinvertebrates was repeatedly counted over almost four decades. Although the transects are each approximately 10 m long, as measured with a meter tape extended between start and end eyebolts set in the sea floor, crevices, boulders, and reef structure provide much more than 20 square meters of surface area. In an effort to quantify the differences in rugosity between the transects, a 13 cm-circumference electronic surveyor’s wheel was used to measure...
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The data consist of counts of sea urchins in quadrats from over 600 nearshore rocky bottom sites that were sampled by scuba between 1987 and 2021. The sites are from 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to Southeast Alaska. At each site, divers counted and collected sea urchins from quadrats placed at random distances mostly along a 20-25-foot depth contour. At a subset of sites, 40-foot depths were targeted. Urchins were counted until either 20 quadrats were sampled or about 200 urchins were collected. Quadrat size is specified in the data table but was 0.25 m2 at almost all sites. At the same sites where urchins were counted,...
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The GIS shapefile Census_sum_2019 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 2019 range-wide census. The USGS spring range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. This shapefile includes a series of summary statistics derived from the raw census data, including sea otter density (otters per square kilometer of habitat), linear density (otters per kilometer...
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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. The USGS spring range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. 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...
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The data consist of latitude and longitude of over 600 nearshore rocky bottom sites that were sampled by SCUBA between 1987 and 2021. The sites are from 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to Southeast Alaska. At each site, counts were made of kelp species and estimates made of the percent cover of fleshy red and other benthic algae, as well as cover by non-motile invertebrates, in twenty 0.25 m2 quadrats. Urchins were counted and collected from quadrats until either 20 quadrats were sampled or about 200 urchins were collected. Kelp and bottom cover data and the urchin density and size data are presented in other tables. Many...
The data consist of blood chemistry and hematology from sea otters captured at sites along the Aleutian archipelago, the Alaska Peninsula, the Gulf of Alaska, and Prince William sound between 2004 and 2012. The data include the blood chemistry and hematology findings as well as general capture location, if the sea otter population in that area is declining, capture date, age estimate, age class, sex, and a unique sea otter number connecting the sample to gene expression data.
The data table consists of a compilation of sea otter survey results from Bering Island, Russia and select Western Aleutian Islands conducted between 1959 and 2015. The counts were reduced to sea otters per kilometer of coastline for temporal comparability. A correction factor of 3.6 was applied to aerial survey totals to yield results comparable to skiff based surveys. The data table provides the island, year, mode (aerial, skiff, or ground), and shore length covered in each survey. Counts of independent otters and pups are provided if available. Total otters counted or calculated with the correction factor and the calculated linear density are also provided.
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Between 1987 and 2021, over 600 nearshore rocky bottom sites were sampled by scuba at 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to southeast Alaska. Sites were plotted at random from along the coasts of islands or areas designated. Hard substrate was targeted. Most sites were sampled more than once, years or decades apart. Many sites in the western Aleutians were resampled several times as sea otter populations densities changed there. Each site was sampled using 20 quadrats along 20-25-foot depth contour. At a subset of sites, 40-foot depths were sampled. Divers counted kelps but non-motile invertebrates, Desmarestia spp. (acid weed),...
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The GIS shapefile "Extra limit counts of southern sea otters 2018" is a point layer representing the locations of sea otter sightings that fall outside the officially recognized range of the southern sea otter (Enhydra lutris nereis) in mainland California. These data were collected during the spring 2018 range-wide census. The USGS range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. Sea otter distribution in California (the mainland range) is considered to comprise a band of potential habitat stretching...
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The data consist of counts of kelps and estimated percent cover of fleshy red algae, other benthic algal cover, and non-motile invertebrates in quadrats from over 600 nearshore rocky bottom sites that were sampled by scuba between 1987 and 2021. The sites are from 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to southeast Alaska. At each site, divers counted kelps and estimated percent cover of other algae and encrusting invertebrates in 20 quadrats along 20-25-foot depth contour. At a subset of sites, 40-foot depths were targeted. Quadrat size is specified in the data table but was 0.25 m2 at almost all sites. At the same sites where kelps...
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The GIS shapefile Range extent of southern sea otters 2019.shp is a simple polyline representing the geographic distribution of the southern sea otter (Enhydra lutris nereis) in mainland California, based on data collected during the spring 2019 range-wide census. The USGS range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring provides the primary basis for gauging population trends by State and Federal management agencies. Sea otter distribution in California (the mainland range) is considered to comprise a band of potential habitat stretching along the coast of California, and bounded to the north and south...
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The spring 2019 mainland sea otter count began on May 1 and was completed by July 9. Overall viewing conditions this year were very good, better than those encountered during the 2018 spring census (View Score = 3.0 this year compared to 2.4 last year, where 0=poor, 1=fair, 2=good, 3=very good, and 4=excellent). The surface canopies of kelp (predominantly Macrocystis pyrifera) were qualitatively noted by observers to be much less than the seasonal normal in the central portions of the range (from Monterey to Cayucos) and about normal near both ends of the range. Sea otters along the mainland coast were surveyed from Pigeon Point in San Mateo County in the north, to Santa Barbara Harbor in Santa Barbara County in...
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Three data sets are included here to aid in assessment of the sea otter population collapse in southwest Alaska. One data set consists of results of sea otter surveys conducted between 1959 and 2015 at Bering Island, Russia and a selection of western Aleutian Islands in Alaska. Sea otter counts are reduced to a comparable value of otters per linear kilometer. Another data set consists per-capita and per kilometer recovery rates of stranded sea otter carcasses from locations ranging from Bering Island, Russia, several Aleutian Islands, sites along the Alaska Peninsula, and Prince William Sound, Alaska. These data are mainly from the period 1991-2009 and are from stable populations as well as those in decline or post...
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The data represent total counts of adult California sheephead from six long-term sites at San Nicolas Island, CA between fall 1981 and spring 2018. At each site counts were made by divers swimming five 50-m by 5-m mid-water transects and five 50-m by 2-m benthic transects. The data presented here are the sum of the adult sheephead counted on all transects at a site for each sampling period. The data are from samples made in fall and spring from 1981-2018.
Two data sets concerning organic contaminants are included here to aid in assessment of the sea otter population collapse in southwest Alaska. One data set consists of levels of organic pollutant compounds found in wild sea otter blood collected from captured animals in 1997 (Jessup et al., 2010). These sea otters were captured from islands in the western Aleutians and from outside the area of population collapse, in southeast Alaska near Cross Sound. Another data set consists of levels of organic pollutant compounds found in blue mussels collected from multiple sites along the Aleutian archipelago and from the Cross Sound area in southeast Alaska in 1994-1996 (Reese et al., 2012). These data support the following...
The table presents summary data of sea otter skulls found on carcass searches conducted along stretches of shoreline at islands or locations along a longitudinal span encompassing the sea otter population decline. Numbers of skulls encountered, length of shoreline searched, population density calculated from survey data, as well as skulls per kilometer and per-capita recovery rate are presented. The data are arranged in west to east order from Bering Island to Prince William Sound.


map background search result map search result map Annual California Sea Otter Census: 2018 Census Summary Shapefile Annual California Sea Otter Census: 2018 Extra Limit Observations Shapefile Annual California Sea Otter Census - 2019 Spring Census Summary Annual California Sea Otter Census: 2019 Census Summary Shapefile Annual California Sea Otter Census: 2019 Extra Limit Observations Shapefile Annual California Sea Otter Census: 2019 Range Extent Shapefile Sea Otter Survey Data, Carcass Recovery Data, and Blood Chemistry Data from Southwest Alaska Sea otter surveys from selected Western Aleutian Islands, Alaska and Bering Island, Russia between 1959-2015 Sea otter carcass recovery rates from Bering Island, some Western Aleutian Islands, the Alaskan Peninsula and Prince William Sound, 1971-2009 Sea otter blood chemistry and hematology from animals captured at sites between Bering Island, Russia and Prince William Sound, Alaska during 2004-2012 Persistent Organic Pollutants in Sea Otter Blood and in Blue Mussels from the Aleutian Islands and Southeast Alaska Levels of Persistent Organic Pollutants Found in Blue Mussels (Mytilus trossulus) in the Aleutian Archipelago and Southeast Alaska in 1994-1996 Levels of Persistent Organic Pollutants Found in the Blood of Sea Otters Captured in the Western Aleutian Islands and Southeast Alaska in 1997 Adult California Sheephead (Semicossyphus pulcher) Counts at Long-term Subtidal Sites at San Nicolas Island, California (1981-2018) Hourly Sea Floor Water Temperatures Recorded at Four Kelp Forest Monitoring Sites at San Nicolas Island, California (2015-2019) Linear Distance as a Measure of Substrate Rugosity of Permanent Benthic Transects at San Nicolas Island, California Kelp and Sea Urchin Data Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska Obtained over Multiple Decades Beginning in 1987 Latitude and Longitude of Shallow Nearshore Sites Sampled by SCUBA for Kelp Abundance, Bottom Cover, and Sea Urchin Density and Size Distribution along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Kelp Counts and Bottom Cover Estimates Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Sea Urchin Counts Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Annual California Sea Otter Census: 2018 Extra Limit Observations Shapefile Annual California Sea Otter Census: 2019 Extra Limit Observations Shapefile Adult California Sheephead (Semicossyphus pulcher) Counts at Long-term Subtidal Sites at San Nicolas Island, California (1981-2018) Hourly Sea Floor Water Temperatures Recorded at Four Kelp Forest Monitoring Sites at San Nicolas Island, California (2015-2019) Linear Distance as a Measure of Substrate Rugosity of Permanent Benthic Transects at San Nicolas Island, California Annual California Sea Otter Census: 2019 Range Extent Shapefile Annual California Sea Otter Census - 2019 Spring Census Summary Annual California Sea Otter Census: 2018 Census Summary Shapefile Annual California Sea Otter Census: 2019 Census Summary Shapefile Sea otter surveys from selected Western Aleutian Islands, Alaska and Bering Island, Russia between 1959-2015 Persistent Organic Pollutants in Sea Otter Blood and in Blue Mussels from the Aleutian Islands and Southeast Alaska Levels of Persistent Organic Pollutants Found in Blue Mussels (Mytilus trossulus) in the Aleutian Archipelago and Southeast Alaska in 1994-1996 Levels of Persistent Organic Pollutants Found in the Blood of Sea Otters Captured in the Western Aleutian Islands and Southeast Alaska in 1997 Kelp and Sea Urchin Data Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska Obtained over Multiple Decades Beginning in 1987 Latitude and Longitude of Shallow Nearshore Sites Sampled by SCUBA for Kelp Abundance, Bottom Cover, and Sea Urchin Density and Size Distribution along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Kelp Counts and Bottom Cover Estimates Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Sea Urchin Counts Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021 Sea otter carcass recovery rates from Bering Island, some Western Aleutian Islands, the Alaskan Peninsula and Prince William Sound, 1971-2009 Sea Otter Survey Data, Carcass Recovery Data, and Blood Chemistry Data from Southwest Alaska Sea otter blood chemistry and hematology from animals captured at sites between Bering Island, Russia and Prince William Sound, Alaska during 2004-2012