A tale of two fishes: using recreational angler records to examine the link between fish catches and freshwater inflows in a subtropical mangrove estuary

Maintaining natural freshwater inflows is critical to conserving and managing estuarine fisheries. Natural flow regimes are particularly important in tropical and subtropical regions, where seasonal high flow events hydrologically connect permanent water bodies with adjacent flood plains. In mangrove-dominated Everglades estuaries, seasonal inundation of upstream marshes may play an important role in provisioning its world-renowned recreational fishery. Yet, little is known about how the dynamics of freshwater inflows and extent of marsh inundation interacts with estuarine fisheries production. Thus, we examined the importance of both wet season amplitude (annual peak marsh water height) and duration of drydown (days marshes dried per year) of upstream marshes in driving catch rates of largemouth bass and snook in the estuary. These are two economically-important recreational species that due to their freshwater and estuarine nature are expected to differ in responses to hydrological conditions. We used angler records from 1992 to 2012, and validated these data by comparing angler catches to fisheries independent data taken in the same region from 2004 to 2012. Our results suggest previous year’s marsh dynamics, particularly the duration of marsh drydown, significantly influenced bass and snook catches, but in different ways and with time lags. Bass angler catches were negatively correlated to the severity of marsh drying in the previous year, while snook catches were positively linked to days marshes were dry two years prior. Findings argue for the greater use of recreational records in examining links between important fisheries and key drivers such as freshwater inflows.