Evaluation of Alaska Harbor Seal (Phoca vitulina) population surveys: A simulation study (1995-1996)

We used simulation to investigate robust designs for the Alaska harbor seal population surveys. We employed an operating model approach, creating simulated harbor seal population dynamics and haulout behavior that incorporated all factors thought to potentially affect the performance of aerial surveys. We found that adjusting counts for the effects of covariates such as survey date or stage of tide was both possible and essential. Annual estimates of the average fraction of the population hauled out are also advised.

This project is primarily a re-analysis of existing empirical data collected by the ADF&G and NMFS during studies to assess the population trend and abundance of harbor seals in the Gulf of Alaska, including Prince William Sound. These data are primarily counts of harbor seals obtained from both aerial surveys and land-based
monitoring studies. Additional data include the geographic location of the seal haulout where the counts were obtained, and records of environmental variables associated with the count data: e.g., date, time, tidal stage.

The data here include NMFS survey and tag-and-recapture data, ADF&G data collected by Kathryn Frost, et al. has been archived in package df35b.71.9 and can be found at http://evos.nceas.ucsb.edu/evos/metacat/df35b.71.9/default

Adkison, M. D., T. J. Quinn 11, and R. J. Small. 2001. Evaluation of Alaska Harbor Seal (Phoca vitulina) population surveys: A simulation study, Exxon Valdez Oil Spill Restoration Project Final Report (Restoration Project 00509), Alaska Department of Fish & Game, Division of Wildlife Conservation, Juneau, Alaska.