Abstract

The Steinhatchee Fisheries Management Area (SFMA) is a federally permitted, large-area artificial reef system in the northeastern Gulf of Mexico, designed and constructed to test a bottleneck hypothesis for juvenile gag. Gag have a spatially stage-structured life history, with juveniles (ages 1 - 4) occupying patch reefs on the shallow continental shelf. Prior experiments demonstrated density-dependent habitat selection and growth, with the tension between mortality risk and growth potential favoring available shelter as a primary element of habitat quality. The SFMA is 259 km2 on the shallow shelf, enhanced with 500 “conservation reefs” designed and randomly distributed to improve growth rates and survivorship of juvenile gag. The SFMA is not a “no-take marine protected area”. Instead, locations of small conservation reefs are not publicly known, which in combination with small reef size and wide dispersion is a passive constraint on directed fishing. The evaluation plan involves monitoring reefs offshore that bracket the region, a tagging study and comparisons of gag growth and mortality rates between the SFMA and adjacent, unenhanced shelf areas. Those parameter estimates will be inputs for spatial modeling of habitat effects on gag population dynamics.

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