Winter flounder is an estuarine flatfish found in almost all shoal water habitats along the northwest Atlantic coast. The geographic distribution ranges from nearshore habitats to offshore fishing banks along the Atlantic coast of North America.
The name 'winter' flounder refers to their annual spawning migrations into nearshore waters in winter. Adults migrate in two phases; an autumn estuarine immigration prior to spawning, and a late spring/summer movement to either deeper, cooler portions of estuaries or to offshore areas after spawning. This pattern of seasonal distribution may change in the colder waters of the northern extent of the range where they migrate to shallow water in the summer and deeper waters in the winter. The annual spawning period varies geographically and although spawning periods overlap considerably, peak spawning times are earlier in southern locations.
During spawning, females release demersal (negatively or neutrally buoyant) adhesive eggs whose properties facilitate retention within spawning grounds. Many factors influence larval and juvenile growth and survival, including temperature, salinity, dissolved oxygen, and food availability. Nursery habitat for winter flounder larvae and juveniles is typically saltwater coves, coastal salt ponds, estuaries, and protected embayments; although larvae and juveniles have also been found in open ocean areas such as Georges Bank and Nantucket shoals. Larvae are predominantly found in the upper reaches of estuaries in early spring, moving into the lower estuary later in the season.
The winter flounder commercial fishery was once a highly productive industry with annual harvests up to 40.3 million pounds. Since the early 1980s, landings have steadily declined. Total commercial landings for all stocks (Georges Bank, Gulf of Maine, and Southern New England/Mid-Atlantic combined) dipped to 3.5 million pounds in 2010.. Landings have risen since 2010 due to doubling of quotas in 2011 and again in 2012 for the Gulf of Maine stock, and the lifting of the Southern New England/Mid-Atlantic moratorium in 2013 by NOAA Fisheries. However landings have only increased slightly, the total commercial landings for all stocks combined reached 4.4 million pounds in 2014. Recreational landings peaked in 1982 at 16.4 million pounds and have since maintained a declining trend. In 2013, only 77,000 pounds of winter flounder were harvested – the lowest amount ever recorded for the recreational fishery.
The 2015 Gulf of Maine stock assessment update indicates overfishing is not occurring and the stock biomass is unknown. Based on the Southern New England/Mid-Atlantic (SNE/MA) 2015 stock assessment update the stock is overfished, but overfishing is not occurring. Spawning stock biomass (SSB) in 2014 was estimated to be 13.6 million pounds which is 23% of the biomass target (59.4 million pounds). Fishing mortality was estimated to be 0.16 which is 49% of the overfishing threshold. Since 1981 SNE/MA recruitment has been declining, 2013 is the lowest in the time series which is approximately 4% of the estimated recruitment in 1981 (the highest in the time series). While the 2014 SNE/MA recruitment estimate increased slightly, the overall stock productivity continues to decline. The stock did not meet its rebuilding target in 2014, in part due to low recruitment. In 2014, NOAA Fisheries partially implemented Framework Adjustment 50 to revise the rebuilding end date to 2023. Heavy fishing pressure, habitat degradation, and low genetic variability hinder winter flounder recovery.
Winter flounder in eel grass. Photo credit: Carl Lobue, The Nature Conservancy
The Commission and the New England Fishery Management Council jointly manage winter flounder with complementary management plans that regulate state and federal waters based on fisheries and the biology of winter flounder. The Council includes winter flounder as part of the Northeast Multispecies Fishery Management Plan (Groundfish FMP). Federal management focuses on the commercial fishery because the bulk of harvest in federal waters is from that sector.
The Commission’s Amendment 1 (November 2005) and Addendum I (May 2009) are designed to protect spawning females when they have migrated to inshore state waters spawning grounds because they are easily located and caught when congregated for spawning. The Commission and Council use stock area-specific management measures for both the recreational and commercial sectors of the fishery.
The Commission significantly reduced fishing on state waters spawning grounds in 2005 when Amendment 1 to the Interstate FMP for Inshore Stocks of Winter Flounder (Amendment 1) replaced all previous winter flounder management documents. Amendment 1 established a minimum size limit, shortened seasons, and lowered trip/bag limits to reduce fishing pressure on spawning fish and rebuild the spawning stock biomass to target levels. Amendment 1 complemented Amendment 13 and Framework 42 to the Groundfish FMP, which focused on offshore commercial fisheries (3 - 200 miles). Its goal is to rebuild overfished stocks by reducing fishing mortality and minimizing adverse effects on all essential fish habitat with seasonal closures, gear restrictions, minimum size limits, trip limits, limited access, and days at-sea restrictions.
Considerable management changes occurred in 2009 following the 2008 peer-reviewed benchmark assessment, which estimated the Southern New England/Mid-Atlantic stock at 9% of the target biomass. To rebuild the depleted stock, the Commission initiated Addendum I, the Secretary of Commerce prohibited retention of Southern New England/Mid-Atlantic winter flounder through interim action, and the Council included measures to incorporate the assessment results into Amendment 16 to the Groundfish FMP (Amendment 16). Rather than prohibit possession of winter flounder, resulting in increased discard mortality and loss of fishery-dependent data, the Commission opted to establish bycatch-only possession limits for the Southern New England/Mid-Atlantic stock. Addendum I limits recreational fishermen to 2 fish and commercial fishermen can land a maximum of 50 pounds (or 38 fish) in the Southern New England/Mid-Atlantic. For the Gulf of Maine, Addendum I required states to reduce recreational fishing mortality by 11% and established a 250 pound commercial trip limit.
In October 2012, in response to updated stock status information and recent federal action to increase the Gulf of Maine winter flounder state waters' estimated harvest level, the Commission's Winter Flounder Management Board approved Addendum II. The Addendum modified the commercial and recreational management requirements for the Gulf of Maine stock. Specifically, the commercial trip limit was increased to 500 pounds per trip and the recreational season was expanded to become year round. These measures applied only to Gulf of Maine state waters' fisheries until June 1, 2013. In May 2013, the Board passed Addendum III for the Gulf of Maine and Southern New England/Mid-Atlantic fisheries in order to annually set commercial and recreational specifications. These specifications may be set for up to 3 years, and may be revised if new information is released within the 3 year period. For the 2014 fishing year, the Winter Flounder Management Board maintained commercial and recreational regulations for state waters, with the exception of extending the Southern New England/Mid-Atlantic recreational season from March 1-December 31.