Characterizing Winter Flounder Populations in Massachusetts Waters.

Zarrella Smith, Katrina A.*¹, William S. Hoffman², Bradley P. Schondelmeier², Micah J. Dean², Adrian Jordaan¹, Michael P. Armstrong², ¹University of Massachusetts, Amherst, MA, ²Massachusetts Division of Marine Fisheries, Gloucester, MA

Diminished winter flounder (Pseudopleuronectes americanus) populations within the Gulf of Maine are expected to inhabit Massachusetts Bay (USA) in their highest abundance, but overall population status and current behavior remains poorly understood. Management decisions are consequently impacted, especially in urban estuaries where multiple ecosystem service needs require consideration. We therefore are using a multi-pronged approach to characterize winter flounder populations, particularly in Boston Harbor, with implications for the Gulf of Maine stock. We tagged 150 adults to acoustically track movements over three years and in combination with sampling reproductive status of Massachusetts landings, we will determine where tagged fish are located along the coast during spawning season. We are also assessing young-of-year (YOY) populations using a weekly beam trawl survey (in Boston Harbor, July–October 2021–2022) to back-track YOY ages to spawning windows and determine what habitat promotes survival. Preliminary analyses suggest that adults do return to Boston Harbor year over year, but spawning locations remain elusive. We hypothesize that YOY are advected into the estuary in a single recruitment window and undertake fine-scale movements between habitats in this system as they grow. We will also be conducting genetic kinship analyses to assess relatedness in sampled populations, potentially linking spawning adults with YOY. With data from multiple approaches, we anticipate characterizing recruitment processes, including YOY mortality rates, in an estuary deemed critical to winter flounder survival.