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Aerial Survey Counts of Harbor Seals in Lake Iliamna, Alaska, 1984-2013 (NCEI Accession 0123188)

Metadata Updated: December 1, 2023

This dataset provides counts of harbor seals from aerial surveys over Lake Iliamna, Alaska, USA. The data have been collated from three previously published sources (Mathisen and Kline 1992; Small 2001; ABR Inc. Environmental Research and Services 2011) and newly available data from the NOAA Alaska Fisheries Science Center and the Newhalen Tribal Council. The survey years range between 1984 and 2013. Counts are reported as summed totals across all identified waypoints in the lake for each survey date.

The NOAA National Marine Mammal Laboratory (NMML) (Alaska Fisheries Science Center, Seattle, Washington, USA) conducted aerial surveys of Iliamna Lake between 2008 and 2013. Surveys were conducted as part of annual harbor seal survey effort and in collaboration with local community participants and researchers at the University of Alaska. Surveys were flown using high wing, twin engine aircraft (Aero Commander 680, 690 or a de Havilland Twin Otter). Survey altitude was generally 330 m and at an aircraft speed of 120 kts. Surveys were performed seasonally for most years between 2008 and 2013. Surveys were timed so that one survey was conducted while the lake was mostly frozen (Late March/early April), one during pupping (mid July), and often several during the August molt, when the greatest number of seals typically haul out on shore. Surveys were flown, weather allowing, in the mid- to late-afternoon, when the number of seals hauled out was expected to be highest. Aircraft flight track was recorded by GPS and all seals sighted were digitally photographed using a high resolution digital SLR camera with a telephoto zoom lens (up to 400mm). Time, date, latitude, longitude, and altitude were automatically saved into the image metadata or georeferenced post survey using the GPS track and software.

The total number of seals hauled out were counted from the digital photographs and recorded for each identified site. Pups were determined by their smaller size, and close proximity (less than 1 body length; either nursing or laying right next) to a larger seal. Pups were no longer recorded beyond about mid-August when many have been weaned and cannot reliably be distinguished from other non-adult seals. In 2009, a collaborative effort between NMML and researchers from the Newhalen Tribal Council (Newhalen Tribal Council 2009) provided 10 additional surveys and similar techniques were used. The raw survey count data from these surveys was provided to NMML. Aerial surveys were authorized under a Marine Mammal Protection Act General Authorization (LOC No. 14590) issued to the NMML.

Between 2005 and 2007, ABR, Inc. Environmental Research and Services conducted a series of aerial surveys for harbor seals in Iliamna Lake (ABR Inc. Environmental Research and Services 2011). In addition, earlier counts from surveys conducted by ADFG (Small 2001) and a 1991 census by Mathisen and Kline (Mathisen and Kline 1992) were incorporated into the dataset to expand the historical reach. Geographic coordinates were provided (or, when not provided, determined based on descriptions or physical maps) for each survey site and these sites were compared and merged with locations identified by NMML. In some cases, sites in very close geographic proximity were combined into a single site.

The iliamna_totalcounts file provides counts (n=96) and observed weather conditions for each survey date. Both total number of adult seals (adulttotal) and total number of identified pups (puptotal) are provided when available. puptotal is recorded as NA when adults and pups were not distinguished. In these cases, the adulttotal value is presumed to include pups. In addition to the seal count information, each record includes observed weather variables (airtemp (in ranges of degrees F), windspeed (in ranges of miles per hour), winddirection (cardinal), and descriptive categories for skycondition and precip). The datetime values correspond to local Alaska time.

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Date 2023-10-17T21:03:08Z
Metadata Created Date December 4, 2020
Metadata Updated Date December 1, 2023
Reference Date(s) January 22, 2015 (publication), June 18, 2015 (revision)
Frequency Of Update asNeeded

Metadata Source

Harvested from NOAA/NESDIS/ncei/accessions

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Additional Metadata

Resource Type Dataset
Metadata Date 2023-10-17T21:03:08Z
Metadata Created Date December 4, 2020
Metadata Updated Date December 1, 2023
Reference Date(s) January 22, 2015 (publication), June 18, 2015 (revision)
Responsible Party (Point of Contact)
Contact Email
Guid gov.noaa.nodc:0123188
Access Constraints Cite as: Withrow, David E.; London, Josh M.; Yano, Kymberly M.; Boveng, Peter L. (2015). Aerial Survey Counts of Harbor Seals in Lake Iliamna, Alaska, 1984-2013 (NCEI Accession 0123188). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. Accessed [date]., Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
Bbox East Long -154.214
Bbox North Lat 59.7512
Bbox South Lat 59.5281
Bbox West Long -154.94
Coupled Resource
Frequency Of Update asNeeded
Graphic Preview Description Preview graphic
Graphic Preview File
Graphic Preview Type PNG
Harvest Object Id 69ee4a33-f5db-47c0-92f9-e1997451c837
Harvest Source Id c084a438-6f6b-470d-93e0-16aeddb9f513
Harvest Source Title NOAA/NESDIS/ncei/accessions
Licence accessLevel: Public
Metadata Language eng
Metadata Type geospatial
Old Spatial {"type": "Polygon", "coordinates": [[[-154.94, 59.5281], [-154.214, 59.5281], [-154.214, 59.7512], [-154.94, 59.7512], [-154.94, 59.5281]]]}
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1984-08-06
Temporal Extent End 2013-08-07

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