T-301A-13
When Is It Better to Use Sex-Specific Assessment Models?

Tuesday, August 19, 2014: 2:30 PM
301A (Centre des congrès de Québec // Québec City Convention Centre)
Michael J. Wilberg , Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD
Andrea L. Sylvia , Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD
David C. Kazyak , Wildlife Ecology, University of Maine, Orono, ME
Sarah Rains , ACCSP
Cara Simpson , Chesapeake Biological Laboratory, University of Maryland Center for Environmental Sciences, Solomons, MD
Many fish and shellfish species have traits or management that cause fishing mortality to differ between sexes.  In contrast, most stock assessments use sex-aggregated data and models to determine stock status and to provide fishing level recommendations.  The disconnect may cause poor performance of common assessment techniques when sex-specific differences in fishing mortality occur.  We conducted a simulation study of the accuracy of sex-specific and sex-aggregated stock assessment models under three scenarios of sex-specific fishing mortality: 1) no differences between the sexes, 2) differences between the sexes based on size-specific selectivity and sexually dimorphic growth, and 3) differences in fishing mortality and selectivity between the sexes. In addition to the sex-aggregated assessment model, two sex-specific assessment models were fitted to data sets: one with sex-specific data only available for a survey, and one with sex-specific data available for all data sources.  The data generating model was based on the life history and fisheries for Summer Flounder in the Mid-Atlantic US.  Preliminary results indicate all three assessment models perform reasonably well when sex-specific differences are absent, but model accuracy diverges when sex-specific differences increase.