Winter Flounder Navigate the Postsettlement Gauntlet with a Bet-Hedging Strategy

Winter Flounder Pseudopleuronectes americanus, a coastal flatfish species of historically economic and cultural importance, have declined throughout the past few decades within the southern New England and mid-Atlantic region of the United States, reaching a low point of less than 9% of their historic biomass in 2009. Unusually high postsettlement mortality is thought to impose a critical recruitment bottleneck on the population, potentially stalling recovery of Winter Flounder populations despite management measures. Survival and growth during early life history play a key role in the recruitment dynamics of marine fishes. Spatiotemporal differences in these vital rates from young-of-the-year (i.e., age-0) Winter Flounder have been variously linked to environmental gradients, anthropogenic stressors, differences in the timing of settlement, and location. To better understand local declines in recruitment productivity, we assessed vital rates of age-0 Winter Flounder in five different bays in Long Island, New York. A weekly or biweekly beam-trawl survey targeting age-0 Winter Flounder was implemented over five summers. We compared survey-based estimates of age-0 mortality and growth, finding significant differences between locations in growth but not mortality. A consistently high abundance of age-0 Winter Flounder in Shinnecock Bay and Mattituck Creek was prolonged by a secondary settlement pulse later in the season. Hypothesizing that multiple settlement pulses are a bet-hedging strategy against temporally varying environmental conditions, we compared mortality, growth, and occupied habitat conditions between settlement pulses (cohorts), finding differences in growth and habitat occupancy that varied across years.