A coastal lagoon-spawning Winter Flounder subpopulation during ecosystem and fisheries shifts

Abstract Objective This research collates numerous data sets, including long-term fisheries monitoring surveys, predators, water quality, and fishing pressure, to explore possible biotic and abiotic correlates that may be hindering the recovery of a Winter Flounder Pseudopleuronectes americanus subpopulation. Methods Age-0 (i.e., young-of-year) Winter Flounder and spawning contingents within a single coastal lagoon, Point Judith Pond (Rhode Island), were evaluated across two decades (1999–2020) to determine how potential ecological drivers and harvest have contributed to the subpopulation's state. Available data sets describing predators of both age-0 and adult Winter Flounder, fecal coliform measurements, water temperature, and commercial and recreational harvest were run in a correlative analysis with age-0 and adult Winter Flounder. Result Despite decreases in fishing mortality within the pond, there has been no recovery within the Point Judith Pond subpopulation—a shared response across the stock unit. Although it is possible that an increase in predators of eggs, age-0 Winter Flounder, and spawning adults may be hindering the recovery of this subpopulation, other characteristics, such as water quality, habitat degradation, and prey availability, may also be important contributing factors. The survival rates of age-0 Winter Flounder through their first summer appear to have been relatively unchanged over the course of the research, but there has been a contraction in both the spawning period and the maximum size of adult female Winter Flounder in the study area. Conclusion By the time a fishing moratorium was implemented in Point Judith Pond, Winter Flounder abundance was already below time series historic minimums. With fishing pressure seemingly no longer regulating population size, other management strategies must be developed to address natural mortality and habitat degradation.