Search

Winter flounder, Pseudopleuronectes americanus, from southern New England and the Gulf of Maine were historically considered to be obligate estuarine spawners. However, recent experiments and observations document that winter flounder in the Gulf of Maine also utilize coastal waters for spawning. An individual-based modeling approach was used to investigate the transport of winter flounder larvae from three hypothesized coastal spawning grounds in the Gulf of Maine. Transport success rates were greatest for larvae released from Ipswich Bay, intermediate for Stellwagen Bank and least successful for those released from Jeffreys Ledge. There was substantial interannual variability in larval transport and geographic patterns of potential connectivity. Furthermore, the date of spawning had an important influence on transport success. Model results suggest that certain coastal spawning grounds used by winter flounder may serve as an important source of larvae to estuaries and nearshore nursery areas. The potential influx of coastal spawned larvae could have implications for the resilience, productivity and gene flow in local populations. Model results provide further support for the conclusion that winter flounder in the Gulf of Maine may not be solely dependent upon estuaries for spawning. Results also suggest that coastal spawning groups should be considered explicitly in the management of winter flounder, and protected under Essential Fish Habitat regulations. [ABSTRACT FROM AUTHOR]

Abstract: With the exception of fish in the Georges Bank stock, it is widely believed that adult winter flounder (Pseudopleuronectes americanus) in US waters move inshore into estuaries and coastal embayments to spawn. However, there have been many indications that this paradigm may not apply to populations in the Gulf of Maine. To understand winter flounder spawning movements and habitat use more clearly, 40 ripe, pre-spawning adult fish were tagged with acoustic transmitters offshore and tracked in 2009 in the western Gulf of Maine. In addition, winter flounder collected by bottom trawl in the offshore study area were tagged with conventional tags, examined to quantify how the reproductive status of the general population changed over time, and released. Peak spawning of winter flounder in Ipswich Bay occurred in late April to early May. Only six fish (16%) were detected entering estuaries between the end of April and August, indicating that the majority of the tagged fish did not spawn in estuaries but remained in deeper, coastal waters. Surveys made within a New Hampshire estuary when one tagged female was present (May–June) revealed that all captured adults had already spawned and were actively feeding. As of May 2012, conventional tagging returns (395 fish tagged, 5% return rate) show both long and short movements. Fish have been recaptured approximately 0.6–57.2km from their tagging sites in depths of 2–75m. Days at liberty range from 33 to 453 days, with an average of 171 days. Recaptured fish in the study area in the subsequent year adds to the evidence that winter flounder may display spawning site fidelity. However, relocations of fish well outside of Ipswich Bay suggest mixing of populations of winter flounder is likely. Based on the results of this study, consideration should be given to extending the Essential Fish Habitat for Gulf of Maine winter flounder to include near-shore coastal waters during the spawning season. [Copyright &y& Elsevier]

This study explored whether winter flounder, a benthic species, are potentially exposed to contaminants such as heavy metals released from the sediment of the Bay of Fundy/Gulf of Maine, both critical habitats identified to have increases in heavy metal levels. Experimentally in fish, exposure to certain heavy metals resulted in reduced weight for length and structural abnormalities, but it is unknown if this occurs in wild fish. Winter flounder (n = 72), harvested between 2015 and 2018 from the aforementioned western Atlantic region of Canada/USA, had detectable levels of most heavy metals, with some exhibiting levels of concern (arsenic, cadmium, lead, selenium, zinc) in muscle, liver, and kidney. A 1.4% incidence of structural abnormalities was noted. When compared to 1980 regionally matched flounder data, the 2018 flounder had significantly reduced weight for length, exacerbated with age. Clearly winter flounder are affected by worsening heavy metal contaminant levels in this geographic area. • Winter flounder had detectable levels of most heavy metals, some at levels of concern. • Significant reductions in weight-for-length, exacerbated with age compared to 1980 • 1.4 incidence of structural abnormalities [ABSTRACT FROM AUTHOR]