Utility of Fishery-Independent Life History Data in Recent SE US Atlantic Stock Assessments

Fishery-dependent (FD) data are often not representative of populations due to regulations such as size limits and closures.  In many cases, fishery-independent (FI) data is the only data available to adequately characterize populations for stock assessments.  In the US South Atlantic, two FI survey partners (MARMAP / SEAMAP-SA and SEFIS) collect abundance and life history data on managed reef fish species.  These data include length and age compositions, sex ratios, and reproductive state.  In several recent stock assessments both FI and FD data were examined for their utility in characterizing several stocks, including vermilion snapper (Rhomboplites aurorubens) and gray triggerfish (Balistes capriscus).  Of the two, vermilion snapper are more regulated and likely more dependent on FI data in assessments compared to gray triggerfish.  In both cases, FI and FD data produced very different growth parameters and only FI data could be used to assess the need for stratified assessment models, such as regional or sex-based.  The inclusion of FI age data for gray triggerfish allowed for realistic von Bertalanffy parameter estimation.  In turn, an age-based estimate of natural mortality was developed from parameters.  FI data alone were used to estimate sex ratios, maturity schedules, and spawning frequency in both species.