Alaska Harbor Seal Glacial Surveys

Floating glacial ice serves as a haul-out substrate for a significant number (10-15%) of Alaskan harbor seals, and thus surveying tidewater glacial fjords is an important component of statewide efforts to estimate seal abundance. Surveys conducted during pupping suggest that glacial haul outs have higher than average productivity and thus may serve as important source populations statewide. The availability of ice for hauling out varies with seasonal glacial dynamics, but over decades of climate change most tidewater glaciers are now retreating toward eventual grounding with many already ceasing to calve ice into the water. Compounding glacial retreat and thinning is the trend at most of these sites toward increasing tourism and a low compliance of tour vessels to seal approach guidelines and regulations. It is thus important to track glacial populations over the long-term especially as various impacts may degrade seal habitat leading to fewer glacial seals and potential impacts to the population state-wide.

There are currently 28 glacial sites that have at least one actively calving tidewater glacier and in turn seals that haul out on the ice during the seals’ molting period, when most surveys have occurred. Due to concerns about vessel disturbance, Disenchantment and Icy Bays have been surveyed during molting almost annually between 2001-2011 (ex 2003); surveys occurred during pupping and molting in 2004 and 2005, and have occurred just during molting apx. every other year since 2011. Johns Hopkins Inlet in Glacier Bay has been surveyed annually using these methods since 2007, with surveys occurring during both pupping and molting. The remaining 25 sites have been surveyed on an opportunistic schedule (based on weather and aircraft availability), which for most sites equates to about every 2-3 years. Some of the smallest sites have been surveyed on a 4-5 year schedule. These schedules will likely continue with more abundant sites in Prince William Sound (e.g., College Fjord and Columbia) and Southeast Alaska (Tracy Arm, Endicott Arm, LeConte Bay, and Glacier Bay) having higher priority and contingent on management concerns.

The purpose of this data set is to provide a single collection of location data of individual harbor seals and aerial coverage from survey flights at tidewater glacial fjords in Alaska, conducted using the LATTE method (haulout area sampled; Jansen et al. 2015). Three data types are provided: 1) coordinates of individual seals identified from imagery and mapped in a GIS (projected in AK Albers equal area at WGS84); 2) coordinates of the spatial coverage (on the ground) of each image collected; and 3) the coordinates that define a polygon outlining the entire survey area at each site. Only seals hauled out on the ice have been mapped. To estimate total abundance it would be necessary to estimate the number of seals not detected because they were in the water, and to estimate seals that occurred in areas not photographed.

J. K. Jansen, G.M. Brady, S.P. Dahle, K.M. Yano, E.L. Richmond, J.M. Womble (2015): Alaska Harbor Seal Glacial Surveys. Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration. --doi:TBD, contact authors for updated citation details--

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

The data set is in the process of being archived with the NOAA National Centers for Environmental Information. Once the archival process is complete and verified, the data set will be publicly available. Acknowledge NOAA/NMFS/AFSC as the source from which these data were obtained in any publications and/or other representations of these data. Communication and collaboration with dataset authors is strongly encouraged prior to use.

The data set is in the process of being archived with the NOAA National Centers for Environmental Information. Once the archival process is complete and verified, the data set will be publicly available.

The data set is in the process of being archived with the NOAA National Centers for Environmental Information. Once the archival process is complete and verified, the data set will be publicly available.

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty. Acknowledge NOAA/NMFS/AFSC or the specified citation as the source from which these data were obtained in any publications and/or other representations of these data. Communication and collaboration with dataset authors is strongly encouraged.

no metadata access constraints

Metadata are subject to revision at any time and information within the metadata record should not be cited without author consent. While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

CSV file

Not applicable.

Data represented in this dataset are the result of a culmination of multiple observations, data collection protocols and spatial analysis. Through the process various checks are performed to insure data are of the highest quality. These include, but are not limited to: collection of geographic coordinates with high resolution GPS units, high resolution navigational systems on board the aircraft, the use of high resolution DSLR cameras and quality lenses, synching camera time with GPS provided time, and counting of photographs on large, high quality screens with modern software. Despite these quality control checks, users of these data must understand the data are often collected under challenging field conditions and additional processing and testing must be done before these data can be used appropriately.

data are not automatically processed

IT Security and Contingency Plan for the system establishes procedures and applies to the functions, operations, and resources necessary to recover and restore data as hosted in the Western Regional Support Center in Seattle, Washington, following a disruption.

AFSC’s current methods for surveying glacial fjords were first used in 2004, employing a cost-effective technique of high-resolution, vertical photography, using over-the-counter digital SLR cameras adapted to shoot vertically from a plane suitable for flying transects at 1000 feet in sometimes narrow glacial fjords. The resulting high-quality photographs (<4cm per pixel), which represent a sample of the ice habitat, produce spatial maps of seals which can then be used via statistical models to estimate density and ultimately abundance (with standard error). This technique, known as the LATTE method (short for Low AlTitude Transect Estimation), has been incrementally improved with higher resolution cameras (from 10 to 25 MP), faster, more accurate GPS’s to aid in transect navigation, and a system that has a 3-camera, forward motion-compensating camera system to increase coverage and reduce flight time.