DOI: 10.5061/dryad.d51c5b0cd
title: Current and future habitat suitability of Northern fur seals and overlap with the commercial walleye pollock fishery in the Eastern Bering Sea

description: Understanding the abiotic and biotic drivers of species distribution is
 critical for climate-informed ecosystem management. We aimed to understand
 habitat selection of Northern fur sealsin the Eastern Bering Sea, a
 declining population that is also a key predator of walleye pollock, the
 target species for the largest U.S. commercial fishery. We developed
 species distribution models using random forest models by combining
 satellite telemetry data from lactating female fur seals tagged at
 different rookery complexes on the Pribilof Islands in the Eastern Bering
 Sea with regional ocean model simulations. We exploredhow data aggregation
 at two spatial scales (Pribilof-wide and complex-specific) impacted
 modelperformance and predicted distributions. Spatial predictions under
 hindcasted (1992 - 2018) and projected (2050 - 2059) physical and
 biological conditions were used to identify areas of core habitat, overlap
 with commercial fishery catches, and potential changes in future habitat
 suitability. The most important environmental predictor variables across
 all models were bathymetry, bottom temperature, and surface temperature.
 The Pribilof-wide model both under- and overrepresented the importance of
 specific areas, while complex-specific models exhibited considerable
 variability in transferability performance. The majority of core habitat
 occurred on the continental shelf in areas that overlapped with commercial
 catches of walleye pollock during the “B” season (June - October), with an
 average of 76% of the total percentage of the catch occurring in core fur
 seal habitat within the foraging range of lactating females. Projections
 revealed that considerable changes in fur seal habitat suitability may
 occur in the coming decades, with complex-specific variation in the
 magnitude and direction of changes. Our results illustrate the need to
 sample multiple sites whenever possible and consider spatial scale when
 extrapolating species distribution model output for central-place
 foragers, even when terrestrial sites are &lt;10 km apart. The high
 overlap between suitable fur seal habitat and commercial fishery catches
 of pollock, coupled with projected changes in habitat
 suitability,underscore the need for targeted studies investigating
 fisheries impacts on this declining population.
description: Lactating adult female Northern fur seals from St. Paul (57.19º
 N, 170.25º W) and St. George Islands (56.60º N, 169.55º W)<strong>
 </strong>Alaska, USA<strong> </strong>were instrumented
 with satellite tags between 1992 and 2018. Tags remained on females for 1
 - 14 foraging trips. Satellite telemetry data were analysed using a
 continuous-time correlated random walk model to generate hourly predicted
 locations for each trip. Pseudo-absences were generated using a
 first-order vector-autoregressive model that resulted in 100 simulated
 trips that mimicked the speed and duration of each original trip.
 Environmental data from a regional ocean simulation model for the Bering
 Sea were extracted at each presence and pseudo-absence, including
 bathymetry and dynamic physical (e.g., bottom temperature) and biological
 (e.g., phytoplankton biomass) variables. Absences and pseudo-absences were
 classified to a habitat type based on bathymetry (continental shelf or
 basin) and datasets were subsequently split by habitat type. Hourly
 locations were randomly downsampled to a single location per day. Daily
 locations from each foraging trip were paired with corresponding locations
 from a simulated trip so that each trip had the same number of presences
 and pseudo-absences. Ten replicate datasets were created for each habitat
 type to assess how different presences (randomly selected daily locations)
 or pseudo-absences (different simulated trips) affected model output.
 Additional details are provided in the manuscript associated with this
 dataset. 
description: # Current and future habitat suitability of Northern fur seals and overlap
 with the commercial walleye pollock fishery in the Eastern Bering Sea
 [https://doi.org/10.5061/dryad.d51c5b0cd](https://doi.org/10.5061/dryad.d51c5b0cd) ## Description of the data and file structure Northern fur seal data were generated from satellite tagging efforts of adult females between 1992 and 2018. Environmental variables were derived from regional ocean model simulations ([https://github.com/beringnpz/roms-bering-sea).](https://urldefense.com/v3/__https:/github.com/beringnpz/roms-bering-sea__;!!K-Hz7m0Vt54!g5NeitFAV_3QDabHdExrYtaYhlevqpopPTOov174OwYIPH-cJpZJ9_HmICr43-YwHDcG6cXcynw8SZbFmUOAtNGF$)Data are provided in a zip file that contains data in both an excel and R data file, where each row corresponds to a single location (either a presence or an absence) with associated values of environmental variables at that location. ### Files and variables #### File: McHuron et al\_Northern\_fur\_seal\_habitat\_suitability\_input\_data.zip \**Description:**Input data for species distribution models generated from satellite telemetry data collected from northern fur seals on the Pribilof Islands and regional ocean model simulations. ROMS source code can be found at[https://github.com/beringnpz/roms-bering-sea.](https://urldefense.com/v3/__https:/github.com/beringnpz/roms-bering-sea__;!!K-Hz7m0Vt54!g5NeitFAV_3QDabHdExrYtaYhlevqpopPTOov174OwYIPH-cJpZJ9_HmICr43-YwHDcG6cXcynw8SZbFmUOAtNGF$)Simulation output is publicly available at [https://data.pmel.noaa.gov/aclim/thredds/catalog/files.html](https://urldefense.com/v3/__https:/data.pmel.noaa.gov/aclim/thredds/catalog/files.html__;!!K-Hz7m0Vt54!g5NeitFAV_3QDabHdExrYtaYhlevqpopPTOov174OwYIPH-cJpZJ9_HmICr43-YwHDcG6cXcynw8SZbFmYRDdIdT$) ##### Variables * ageclass: The age class of the tagged individual * habitat: Whether a location occurred in the "basin" or "shelf" model * Replicate: The population replicate number. Separate models were created for each population replicate to understand how the specific daily locations influenced model output * island: Tagging island, either St. Paul or St. George * Complex: Tagging complex, * Year: Year of tagging * trip: Trip number comprised of an individual id_trip number * occ: Whether the location was a presence (1) or absence (0) * Bathymetry: Bathymetry (in m) derived from regional ocean model simulations * Cop_integrated: Large copepod biomass integrated over depth (mg C m-2) derived from regional ocean model simulations * Eup_integrated:Euphausiid biomass integrated over depth (mg C m-2) derived from regional ocean model simulations * PhL_integrated:Large phytoplankton biomass integrated over depth (mg C m-2) derived from regional ocean model simulations * PhL_integrated1yrAvg:Average integrated large phytoplankton biomass (mg C m-2) of monthly averages between April and July per year * temp_bottom5m:The average temperature in the bottom 5 m of the water column derived from regional ocean model simulations in degrees Celcius. * temp_surface5m:The average temperature in the top 5 m of the water column derived from regional ocean model simulationsin degrees Celcius. ## Code/software Data are provided in an excel/R data file.