Abstract Objective Spot Leiostomus xanthurus is a forage fish that supports important commercial and recreational fisheries along the U.S. Atlantic coast. Our objectives were to (1) develop standardized indices of biomass using commercial fisheries data, (2) determine whether trends in biomass indices varied spatially over time, and (3) estimate effects of potential environmental drivers on biomass index trends. Methods We calculated indices of biomass using catch per unit effort from commercial gill-net fisheries from New Jersey to Florida. Dynamic factor analysis (DFA) was used to test for spatial differences in biomass trends. Results Indices of biomass varied over space and time. Indices of biomass may have increased over time in the northern states, whereas indices in Maryland showed a declining trend over time. Indices in the southern states varied over time without showing substantial trends. The results of the DFA indicated that trends in relative biomass were similar among regions, with deviations from the common trend strongest for Maryland. Environmental covariates do not appear to improve the DFA model fit. Conclusions The relative biomass of Spot was high in the early 2000s before declining through the mid-2000s. The relative biomass began to increase again in recent years after a low in 2016. The use of fishery-dependent indices may help to improve data-limited approaches for Spot management.
Drzewicki et al. (Mon,) studied this question.