Sea Otter Aerial Survey Data from Southeast Alaska, 2002-2003

Identification_Information:

Citation:

Citation_Information:

Originator: Esslinger, G. G. (ORCID:0000-0002-3459-0083)
Publication_Date: 20200513
Title: Sea Otter Aerial Survey Data from Southeast Alaska, 2002-2003
Geospatial_Data_Presentation_Form: tabular digital data
Publication_Information:

Publication_Place: Anchorage, AK
Publisher: U.S. Geological Survey, Alaska Science Center

Other_Citation_Details:

Suggested citation: Esslinger, G. G., 2020, Sea Otter aerial survey data from southeast Alaska, 2002-2003: U.S. Geological Survey data release, https://doi.org/10.5066/P9PYG92B

Online_Linkage: https://doi.org/10.5066/P9PYG92B
Larger_Work_Citation:

Citation_Information:

Originator: Esler, D.
Originator: Monson, D. H.
Originator: Esslinger, G. G.
Originator: Kloecker, K. A.
Publication_Date: 2005
Title: Nearshore Marine Ecosystem Research Program
Geospatial_Data_Presentation_Form: website
Publication_Information:

Publication_Place: Anchorage, AK
Publisher: U.S. Geological Survey, Alaska Science Center

Online_Linkage: https://alaska.usgs.gov/portal/project.php?project_id=99

Description:

Abstract:

The data package "Sea Otter Aerial Survey Data from Southeast Alaska, 2002-2003" provides raw data for examining abundance and distribution of northern sea otters (Enhydra lutris kenyoni) in Southeast Alaska, based on data collected during a series of population-wide aerial surveys. The USGS aerial sea otter surveys have been completed multiple times using consistent methodology involving aerial-based counts. The surveys provide data and a population estimate that federal and state management agencies use for decision making and planning additional research. This data package includes a series of files with the raw digital data that was used for population estimates and population modeling found in related manuscripts.

Purpose:

The purpose of these data are to assess change in the abundance and distribution of sea otters in the waters throughout Southeast Alaska, 2002-2003.

Supplemental_Information:

Sea otters are a keystone predator, well known for structuring the nearshore marine ecosystem through their consumption of invertebrate prey. The dataset consists of 3 comma-delimited files (CSV) exported from Microsoft Excel. The dataset consists of (1) Strip transect counts, (2) Intensive Search Unit (ISU) counts, and (3) Transect coordinates. Sea otter habitat was divided into two strata, high density and low density, based on distance from shore and water depth. The high density stratum extended from shore to 400 m seaward or to the 40 m depth contour, whichever was greater. The low density stratum extended from the high density line to a line 2 km offshore or to the 100 m depth contour, whichever was greater. Bays and inlets less than 6 km wide were sampled entirely, regardless of depth. Survey effort was allocated proportional to expected otter abundance in the respective strata by adjusting the systematic spacing of transects within each stratum. For each aerial survey, a pilot flew an airplane at an altitude of 91 meters over pre-determined transects while an observer searched on one side of the plane and recorded sea otter group counts and locations. Sea otters observed within 400 meters of each transect were later used to estimate abundance. Sea otters sighted beyond the confines of designated transect swaths were also counted and mapped, time permitting. To estimate the number of sea otters in small groups (<20) not detected along transect swaths (e.g., due to diving behavior or the presence of kelp canopy), 400 meter diameter circles (i.e. ISUs) were searched intensively by periodically flying 5 concentric circles around an initiating group. These ISUs were distributed throughout the survey area in an attempt to accurately represent the full range of observation conditions encountered during the survey. When large groups of sea otters (≥20) were sighted on transect, they were circled until a complete count was made. Data are presented as three CSV files:

(1)SEAK 2002-2003 sea otter strip transect counts in WGS84.csv; (2)SEAK 2002-2003 sea otter ISU counts in WGS84.csv; and (3)SEAK 2002-2003 sea otter survey transect coordinates in WGS84.csv

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 2002
Ending_Date: 2003

Currentness_Reference: ground condition

Status:

Progress: Complete
Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Description_of_Geographic_Extent: Nearshore waters in Southeast Alaska
Bounding_Coordinates:

West_Bounding_Coordinate: -137.140000
East_Bounding_Coordinate: -132.000000
North_Bounding_Coordinate: 58.600000
South_Bounding_Coordinate: 54.600000

Keywords:

Theme:

Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:ASC268

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: biota
Theme_Keyword: environment

Theme:

Theme_Keyword_Thesaurus: USGS Biocomplexity Thesaurus
Theme_Keyword: Aerial surveys
Theme_Keyword: Population density
Theme_Keyword: Abundance (organisms)
Theme_Keyword: Marine mammals
Theme_Keyword: Spatial distribution

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: ecology
Theme_Keyword: population dynamics
Theme_Keyword: ecosystem monitoring

Place:

Place_Keyword_Thesaurus: Geographic Names Information System
Place_Keyword: Alaska

Place:

Place_Keyword_Thesaurus: none
Place_Keyword: Southeast

Taxonomy:

Keywords/Taxon:

Taxonomic_Keyword_Thesaurus: None
Taxonomic_Keywords: sea otters
Taxonomic_Keywords: Enhydra lutris kenyoni
Taxonomic_Keywords: northern sea otters

General_Taxonomic_Coverage:

This data set contains aerial observations of northern sea otters, Enhydra lutris kenyoni.

Taxonomic_Classification:

Taxon_Rank_Name: Kingdom
Taxon_Rank_Value: Animalia
Taxonomic_Classification:

Taxon_Rank_Name: Phylum
Taxon_Rank_Value: Chordata
Taxonomic_Classification:

Taxon_Rank_Name: Subphylum
Taxon_Rank_Value: Vertebrata
Taxonomic_Classification:

Taxon_Rank_Name: Class
Taxon_Rank_Value: Mammalia
Taxonomic_Classification:

Taxon_Rank_Name: Subclass
Taxon_Rank_Value: Theria
Taxonomic_Classification:

Taxon_Rank_Name: Infraclass
Taxon_Rank_Value: Eutheria
Taxonomic_Classification:

Taxon_Rank_Name: Order
Taxon_Rank_Value: Carnivora
Taxonomic_Classification:

Taxon_Rank_Name: Suborder
Taxon_Rank_Value: Caniformia
Taxonomic_Classification:

Taxon_Rank_Name: Family
Taxon_Rank_Value: Mustelidae
Taxonomic_Classification:

Taxon_Rank_Name: Subfamily
Taxon_Rank_Value: Lutrinae
Taxonomic_Classification:

Taxon_Rank_Name: Genus
Taxon_Rank_Value: Enhydra
Taxonomic_Classification:

Taxon_Rank_Name: Species
Taxon_Rank_Value: Enhydra lutris
Applicable_Common_Name: sea otter

Access_Constraints: None
Use_Constraints:

It is requested that the authors and the USGS Alaska Science Center be cited for any subsequent publications that reference this dataset. It is strongly recommended that careful attention be paid to the contents of the metadata file associated with these data to evaluate data set limitations, restrictions or intended use.

Data_Set_Credit:

Sea otter group locations from the 2002 and 2003 aerial surveys were digitized by George Esslinger and John Haddix.

Native_Data_Set_Environment:

The original data is stored as Microsoft Excel Workbooks in a Windows operating environment, but has been exported as comma delimited text files for dissemination.

Cross_Reference:

Citation_Information:

Originator: M. T. Tinker
Originator: V. Gill
Originator: G. G. Esslinger
Originator: J. L. Bodkin
Originator: M. Monk
Originator: M. Mangel
Originator: D. H. Monson
Originator: W. Raymond
Originator: M. Kissling
Publication_Date: 2019
Title: Trends in Carrying Capacity of Sea Otters in Southeast Alaska
Geospatial_Data_Presentation_Form: journal article
Publication_Information:

Publication_Place: On-line
Publisher: The Wildlife Society

Other_Citation_Details:

Condensed abstract Sea otters in southeast Alaska have been increasing in numbers since translocations of less than 500 animals in the 1960s. The authors compiled available survey and harvest data and utilized a Bayesian state-space model to estimate past trend and current abundance, providing insights to managers regarding food web implications and informing commercial fishery managers, particularly regarding conflicts between sea otter and shellfish fisheries. At the regional scale, sea otters have increased from ~13,000 animals in 2003 to ~25,000 animals in 2011. Annual growth rate averaged 7.8% regionally but varied at the sub-regional scale and decreased with increasing local otter density. The estimated density at carrying capacity was 4.2 sea otter per square kilometer resulting in an overall carrying capacity of ~75,000 sea otters for all of southeast Alaska.

Online_Linkage: https://doi.org/10.1002/jwmg.21685

Cross_Reference:

Citation_Information:

Originator: G. G. Esslinger
Originator: J. L. Bodkin
Publication_Date: 2009
Title:

Status and trends of sea otter populations in Southeast Alaska,1969–2003

Geospatial_Data_Presentation_Form: Report
Publication_Information:

Publication_Place: On-line
Publisher: U. S. Geological Survey

Other_Citation_Details:

Esslinger, G.G., and Bodkin, J.L., 2009, Status and trends of sea otter populations in Southeast Alaska,1969–2003: U.S. Geological Survey Scientific Investigations Report 2009–5045, 18 p. ABSTRACT Aerial surveys of all known sea otter (Enhydra lutris) habitat in Southeast Alaska (SE AK) in 2002-2003 indicated a population size of 8,949 otters [Standard Error (SE) = 899] at an average density of 0.92 otters per square kilometer. These findings on sea otter distribution and abundance were compared to results from several previous surveys. Sea otters have expanded their range beyond the outer coast of SE AK and currently occupy inside waters such as Glacier Bay and Sumner Strait. This range expansion, along with archeological evidence, supports the hypothesis that sea otters are capable of colonizing inside waters in SE AK. Inside Glacier Bay National Park and Preserve, in northern SE AK, sea otter abundance has increased from 5 in 1995 to 1,266 (SE = 196) in 2002, more than doubling on an average annual basis, indicating immigration and reproduction as factors contributing to population growth. In the remainder of northern SE AK, the estimated abundance has declined from 2,295 in 1987 to 1,838 (SE = 307) in 2002. In southern SE AK, the abundance of sea otters increased from 2,167 in 1988 to 5,845 (SE = 821) in 2003. Overall, population growth rates for sea otters in SE AK between 1987 and 2003 are much lower than rates from previous studies and were unexpected given the amount of unoccupied habitat available in SE AK. Divergent population trajectories were evident between the southern (6.6 percent per year) and northern areas of SE AK (2.0 percent per year). These differences suggest variation in reproductive or survival rates between the areas. Harvest levels between 1989 and 2003 may have had a measurable effect on sea otter populations in SE AK. Available data on age and sex specific fecundity and survival rates could be used to develop age- and sex-structured population matrix models to help guide management and conservation of sea otter populations.

Online_Linkage: https://pubs.usgs.gov/sir/2009/5045/

Cross_Reference:

Citation_Information:

Originator: G. G. Esslinger
Publication_Date: 2019
Title:

Sea Otter Aerial Survey Data from Glacier Bay National Park and Preserve, 1999-2012

Geospatial_Data_Presentation_Form: Data release
Publication_Information:

Publication_Place: On-line
Publisher: U. S. Geological Survey

Other_Citation_Details:

Esslinger, G. G., 2019, Sea Otter aerial survey data from Glacier Bay National Park and Preserve, 1999-2012: U.S. Geological Survey data release.

Online_Linkage: https://doi.org/10.5066/P9SBAFF6

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

At some point prior to conducting an aerial survey, each aerial observer underwent a training program that involved comparing aerial counts with ground-based counts and was able to consistently detect at least 90 percent of the sea otters within ISUs. A group of sea otters was defined as 1 or more sea otters spaced less than 3 otter lengths apart. Adult sea otters were distinguished from pups when possible and are identified as separate fields in the data. However, because the observer was traveling at a speed of 65 miles per hour and an altitude of 91 meters, small pups may not have been detected and large pups were sometimes indistinguishable from adults. Therefore, pup counts should be regarded as minimum counts. Groups greater than 20 sea otters typically contain active individuals which make it more challenging to obtain accurate counts so photographs are occasionally taken and used to check these counts. Sea otters hauled out on land are typically more difficult to sight, but were counted when observed. During the aerial survey, sea otter locations were mapped on paper maps and later digitized into ArcMap (ESRI). Mapped otter locations are approximate and, especially where sea otters were observed in offshore waters devoid of landmarks, may be off by several hundreds of meters.

Logical_Consistency_Report:

We carry out a standard quality assurance quality control (QAQC) procedure for this data. Entries are checked against field data sheets and data standards for accuracy, missing values, outliers, and inconsistencies. When applicable, data are checked against validated ranges. For several attributes, "." is used as the null value.

Completeness_Report:

During the time of this survey (2002-2003), sea otters were expanding their range into nearshore habitats where they had been extirpated during the maritime fur trade. This survey was designed to cover all habitat in Southeast Alaska where sea otters were known or reported to occur in 2002 with the exception of Glacier Bay. Glacier Bay was surveyed as part of a separate effort (https://doi.org/10.5066/P9SBAFF6) and the Glacier Bay survey area boundary partially overlaps the Southeast Alaska survey boundary in Icy Strait. Due to uncertainty surrounding the limits of sea otter distribution, we surveyed beyond where sea otters were known to occur to minimize the probability of missing sea otters. As a result of this survey design, not all of the surveyed habitat was occupied by sea otters. All of the planned survey transects are included in the file named SEAK 2002-2003 sea otter survey transect coordinates in WGS84.csv. However, transects or portions of transects may not have been surveyed if the survey crew encountered: (1) hazardous conditions such as downdrafts, (2) land due to low tide, or (3) sensitive areas such as sea lion rookeries. Transects that were not surveyed are not included in the file named SEAK 2002-2003 sea otter strip transect counts in WGS84.csv. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Transect coordinate accuracy was not tested quantitatively. Many high density transects intersect with the shoreline on at least one end and the vast majority of these planned intersection points seemed to align well with reality during the surveys. However, planned shoreline intersection points may not match reality due to factors such as tidal state (especially on gradually sloping beaches), navigation error, and inaccuracies in the shoreline maps used to design the surveys, mostly resulting from changes in the shoreline from ongoing natural processes such as erosion, sedimentation, or isostatic rebound. Mapped otter locations are approximate and, especially where sea otters were observed in offshore waters devoid of landmarks, may be off by several hundreds of meters.

Lineage:

Methodology:

Methodology_Type: Field
Methodology_Identifier:

Methodology_Keyword_Thesaurus: None
Methodology_Keyword: aerial survey

Methodology_Description:

The methods for designing, and performing aerial surveys are complicated. See Bodkin and Udevitz (1999) for details.

Methodology_Citation:

Citation_Information:

Originator: Bodkin, J.L., and M.S. Udevitz.
Publication_Date: 1999
Title: An aerial survey method to estimate sea otter abundance
Geospatial_Data_Presentation_Form: document
Other_Citation_Details:

Bodkin, J.L., and M.S. Udevitz. 1999. An aerial survey method to estimate sea otter abundance, in Garner, G.W., and others, eds., Marine Mammal Survey and Assessment Methods: Rotterdam, Netherlands, Balkema Press, p. 13-26.https://pubs.er.usgs.gov/publication/87239

Online_Linkage: https://pubs.er.usgs.gov/publication/87239

Process_Step:

Process_Description:

Aerial survey observational data are collected by experienced field observers. Field data were recorded on paper field data sheets for electronic entry at a later time or entered directly into a tablet computer into Microsoft excel spreadsheets.

Process_Date: Unknown

Process_Step:

Process_Description:

Field data sheet QAQC: the aerial observer and then a data manager review the data sheets for missing, illegible, or confusing entries and correct any issues. Spreadsheet QAQC: tabular sea otter counts are checked against maps showing sea otter group counts and locations, and also checked row by row/cell by cell for accuracy and completeness. Basic descriptive statistics were run on the count data to look for outliers or values inconsistent with the protocol. If outliers or inconsistent values were found, corrections were applied to the data. The descriptive statistics are not part of the dataset, but are used for QAQC. Additional details are provided in the entity/attribute section.

Process_Date: Unknown

Spatial_Data_Organization_Information:

Indirect_Spatial_Reference:

Transect start and end coordinates are unique for each Survey_Unit, Year, and Replicate combination in the strip transect count data. Sea otter group coordinates are included for each group in the strip transect count data.

Direct_Spatial_Reference_Method: Point

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.001
Longitude_Resolution: 0.00001
Geographic_Coordinate_Units: Decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: World Geodetic System of 1984
Ellipsoid_Name: World Geodetic System of 1984
Semi-major_Axis: 6378137
Denominator_of_Flattening_Ratio: 298.257223563

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: SEAK 2002-2003 sea otter strip transect counts in WGS84
Entity_Type_Definition:

This is spreadsheet data saved as a comma delimited file. Each record (row) represents one group of observed sea otters along a transect. In the case of no otters observed, each row represents one transect.

Entity_Type_Definition_Source: producer defined

Attribute:

Attribute_Label: SURVEY_UNIT
Attribute_Definition: Up to four character code for the area covered by the survey.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: NSE
Enumerated_Domain_Value_Definition: The NSE unit comprises northern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: SSE
Enumerated_Domain_Value_Definition: The SSE unit comprises southern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: YEAR
Attribute_Definition:

Year of survey; this attribute is preferable to the “date” field for sorting transects within a year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2002
Enumerated_Domain_Value_Definition: Survey conducted in 2002.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2003
Enumerated_Domain_Value_Definition: Survey conducted in 2003.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: DATE
Attribute_Definition:

Date sea otter group was observed, year month day (yyyymmdd). A "." indicates the date was not recorded by the observer because the record is from an off transect sighting.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 20020630
Range_Domain_Maximum: 20030812
Attribute_Units_of_Measure: date

Attribute:

Attribute_Label: OBSERVER
Attribute_Definition:

First initial and first seven letters of last name of aerial observer.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: GESSLING
Enumerated_Domain_Value_Definition: George G Esslinger
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: REPLICATE
Attribute_Definition:

Replicate number; used to designate the order surveys were flown when more than one survey was flown in a given year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 1

Attribute:

Attribute_Label: STRATUM
Attribute_Definition:

Designates which stratum each transect falls within, high density (H) or low density (L). Sea otter groups sighted off-transect have a “.” in this column.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: H
Enumerated_Domain_Value_Definition: High density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: L
Enumerated_Domain_Value_Definition: Low density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: .
Enumerated_Domain_Value_Definition:

Sea otter sighting was not on a transect, so no stratum is designated.

Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: TRANSECT
Attribute_Definition:

Sequential integer number assigned to each transect within a survey when survey is designed. Transect number; designates which transect the sea otter group was observed on, if any. Sea otter groups sighted off-transect have a “0” in this column.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 967

Attribute:

Attribute_Label: GROUP
Attribute_Definition:

Sequential integer number assigned to each group of sea otters along a transect. Group number; used to designate the order sea otter groups were sighted on a given transect. "0" is assigned for otters observed off transect or when no otters are observed along a transect.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 11

Attribute:

Attribute_Label: ADULTS
Attribute_Definition: Number of adult sea otters observed in a group.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 60

Attribute:

Attribute_Label: PUPS
Attribute_Definition: Number of sea otter pups observed in a group.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 16

Attribute:

Attribute_Label: ISU
Attribute_Definition:

Intensive Search Unit; indicates an ISU number if a group of sea otters occurred within an ISU. A "0" in this field indicates no ISUs were flown on that transect. An ISU is a 400m diameter circle, located within the transect strip, where the survey plane flew 5 concentric circles to search for sea otters that were not sighted (for example, because they were diving or camouflaged by kelp). These data were later used to estimate the proportion of sea otters not detected on transects and adjust the overall abundance estimate for each survey accordingly. Sea otter groups sighted during the strip count portion of the ISU are indicated with an ISU number in the file GLBA sea otter strip counts in WGS84.csv and also entered into the file GLBA sea otter ISU counts.csv, linked by the Survey Unit, Year, Replicate, and ISU number.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 123

Attribute:

Attribute_Label: CC
Attribute_Definition:

Complete Count; designates whether a group of sea otters was circled until it was completely counted.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 0
Enumerated_Domain_Value_Definition: No
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 1
Enumerated_Domain_Value_Definition: Yes
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: GROUP_X
Attribute_Definition:

Sea otter group longitude in decimal degrees, WGS84. "." has been entered when there were no otters observed.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: -136.7953987
Range_Domain_Maximum: -132.1081018
Attribute_Units_of_Measure: decimal degrees

Attribute:

Attribute_Label: GROUP_Y
Attribute_Definition:

Sea otter group latitude in decimal degrees, WGS84. "." has been entered when there were no otters observed.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 54.68588815
Range_Domain_Maximum: 58.39675628
Attribute_Units_of_Measure: decimal degrees

Detailed_Description:

Entity_Type:

Entity_Type_Label: SEAK 2002-2003 sea otter ISU counts
Entity_Type_Definition:

This is spreadsheet data saved as a comma delimited file. Each record (row) represents one ISU conducted along a transect.

Entity_Type_Definition_Source: producer defined

Attribute:

Attribute_Label: SURVEY_UNIT
Attribute_Definition: Up to four character code for the area covered by the survey.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: NSE
Enumerated_Domain_Value_Definition: The NSE unit comprises northern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: SSE
Enumerated_Domain_Value_Definition: The SSE unit comprises southern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: YEAR
Attribute_Definition:

Year of survey; this attribute is preferable to the “date” field for sorting transects within a year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2002
Enumerated_Domain_Value_Definition: Survey conducted in 2002.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2003
Enumerated_Domain_Value_Definition: Survey conducted in 2003.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: DATE
Attribute_Definition:

Date sea otter group was observed, year month day (yyyymmdd). A "." indicates the date was not recorded by the observer because the record is from an off transect sighting.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 20020630
Range_Domain_Maximum: 20030812
Attribute_Units_of_Measure: date

Attribute:

Attribute_Label: OBSERVER
Attribute_Definition:

First initial and first seven letters of last name of aerial observer.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: GESSLING
Enumerated_Domain_Value_Definition: George G Esslinger
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: REPLICATE
Attribute_Definition:

Replicate number; used to designate the order surveys were flown when more than one survey was flown in a given year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 1

Attribute:

Attribute_Label: STRATUM
Attribute_Definition:

Designates which stratum each transect falls within, high density (H) or low density (L). Sea otter groups sighted off-transect have a “.” in this column.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: H
Enumerated_Domain_Value_Definition: High density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: L
Enumerated_Domain_Value_Definition: Low density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: ISU
Attribute_Definition:

Intensive Search Unit; indicates the number of a particular ISU. Sequential integer number assigned to each ISU within a survey. An ISU is a 400m diameter circle, located within the transect strip, where the survey plane flew 5 concentric circles to search for sea otters that were not sighted (for example, because they were diving or camouflaged by kelp). These data were later used to estimate the proportion of sea otters not detected on transects and adjust the overall abundance estimate for each survey accordingly. Sea otter groups sighted during the strip count portion of the ISU are indicated with an ISU number in the “ISU counts” data and also entered into the “Strip transect counts” data, linked by the Survey Unit, Year, Replicate, and ISU number.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 123

Attribute:

Attribute_Label: TRANSECT
Attribute_Definition:

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 18
Range_Domain_Maximum: 934

Attribute:

Attribute_Label: GROUP
Attribute_Definition:

Group number, sequential integer number used to designate the order sea otter groups were sighted in a given ISU. A group was defined as 1 or more sea otters spaced less than 3 otter lengths apart.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 8

Attribute:

Attribute_Label: STRIP_ADULTS
Attribute_Definition:

Number of adult sea otters observed in a group while flying the strip count portion of an ISU. When the observer asked the pilot to initiate an ISU, the plane temporarily departed the transect flight path to circle the initiating sea otter group 5 times. Any adult sea otters sighted prior to the first quarter turn of the first circle are included in the “Strip_Adults” count.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 15

Attribute:

Attribute_Label: STRIP_PUPS
Attribute_Definition:

Number of sea otter pups observed in a group while flying the strip count portion of an ISU. When the observer asked the pilot to initiate an ISU, the plane temporarily departed the transect flight path to circle the initiating sea otter group 5 times. Any sea otter pups sighted prior to the first quarter turn of the first circle are included in the “Strip_Pups” count.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 2

Attribute:

Attribute_Label: CIRCLE_ADULTS
Attribute_Definition:

Number of adult sea otters observed in a group while flying the circle count portion of an ISU. When the observer asked the pilot to initiate an ISU, the plane temporarily departed the transect flight path to circle the initiating sea otter group 5 times. Any adult sea otters sighted after the first quarter turn of the first circle are included in the “Circle_Adults” count.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 16

Attribute:

Attribute_Label: CIRCLE_PUPS
Attribute_Definition:

Number of sea otter pups observed in a group while flying the circle count portion of an ISU. When the observer asked the pilot to initiate an ISU, the plane temporarily departed the transect flight path to circle the initiating sea otter group 5 times. Any sea otter pups sighted after the first quarter turn of the first circle are included in the “Circle_Pups” count.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0
Range_Domain_Maximum: 2

Attribute:

Attribute_Label: BEHAVIOR
Attribute_Definition:

Behavior is defined as "whatever the otter was doing before the plane arrived" and recorded for each group as either diving (D) or non-diving (N). A "." indicates the behavior was not recorded by the observer. Diving otters include any individuals that swim below the surface and out of view, whether traveling or foraging. If any individual(s) in a group are diving, the whole group is classified as diving. Non-diving otters are animals seen resting, interacting, swimming (but not diving), or hauled-out on land or ice.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: D
Enumerated_Domain_Value_Definition: Diving, out of view.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: N
Enumerated_Domain_Value_Definition: Non-diving, otter(s) that can be seen.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: .
Enumerated_Domain_Value_Definition: Behavior not recorded.
Enumerated_Domain_Value_Definition_Source: producer defined

Detailed_Description:

Entity_Type:

Entity_Type_Label: SEAK 2002-2003 sea otter survey transect coordinates in WGS84
Entity_Type_Definition:

This is spreadsheet data saved as a comma delimited file. Each record (row) represents one transect endpoint, describing a pool of possible survey transects. Not all transects in this transect coordinate file were surveyed. Transects listed in the strip transect counts file were surveyed.

Entity_Type_Definition_Source: producer defined

Attribute:

Attribute_Label: SURVEY_UNIT
Attribute_Definition: Up to four character code for the area covered by the survey.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: NSE
Enumerated_Domain_Value_Definition: The NSE unit comprises northern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: SSE
Enumerated_Domain_Value_Definition: The SSE unit comprises southern Southeast Alaska.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: YEAR
Attribute_Definition:

Year of survey; this attribute is preferable to the “date” field for sorting transects within a year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2002
Enumerated_Domain_Value_Definition: Survey conducted in 2002.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2003
Enumerated_Domain_Value_Definition: Survey conducted in 2003.
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: REPLICATE
Attribute_Definition:

Replicate number; used to designate the order surveys were flown when more than one survey was flown in a given year.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 1

Attribute:

Attribute_Label: STRATUM
Attribute_Definition:

Designates which stratum each transect falls within, high density (H) or low density (L). Sea otter groups sighted off-transect have a “.” in this column.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: H
Enumerated_Domain_Value_Definition: High density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: L
Enumerated_Domain_Value_Definition: Low density
Enumerated_Domain_Value_Definition_Source: producer defined

Attribute:

Attribute_Label: TRANSECT
Attribute_Definition:

Sequential integer number assigned to each transect within a survey when survey is designed along with a letter indicating which end (E = east, W = west). For example, transect 1 in the otter data spreadsheets is designated here by endpoints 001E and 001W. Note that each stratum within each replicate will have their own 001E and 001W.

Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 001
Range_Domain_Maximum: 967

Attribute:

Attribute_Label: X_Coordinate
Attribute_Definition: Sea otter group longitude in decimal degrees, WGS84.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: -137.09050
Range_Domain_Maximum: -132.01356
Attribute_Units_of_Measure: decimal degrees

Attribute:

Attribute_Label: Y_Coordinate
Attribute_Definition: Sea otter group latitude in decimal degrees, WGS84.
Attribute_Definition_Source: producer defined
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 54.64570
Range_Domain_Maximum: 58.49878
Attribute_Units_of_Measure: decimal degrees

Overview_Description:

Entity_and_Attribute_Overview:

The information contained in these datasets includes strip transect counts, ISU counts, and transect coordinates from sea otter aerial surveys conducted in Southeast Alaska.

Entity_and_Attribute_Detail_Citation:

producer defined

Sea Otter Aerial Survey Data from Southeast Alaska, 2002-2003

Metadata: