Winter Flounder

Life History

Winter Flounder

Winter flounder in eel grass. Photo credit: Carl Lobue, The Nature Conservancy

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.

Commercial & Recreational Fisheries

Winter Flounder

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. Winter flounder is managed as three stocks; Georges Bank (GBK), Gulf of Maine (GOM), and Southern New England/Mid-Atlantic (SNE/MA). Total commercial landings for all three stocks 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 GOM stock, and the lifting of the SNE/MA moratorium in 2013 by NOAA Fisheries. The states, however, have maintained a very restrictive commercial bycatch limit of 50 pounds or 38 fish per trip and a recreational bag limit of two fish in state waters of SNE/MA. Landings have only increased slightly; the total commercial landings for all three stocks reached 3.7 million pounds in 2015. Recreational landings peaked in 1982 at 16.4 million pounds and have since maintained a declining trend. In 2015, 88,223 pounds of winter flounder were harvested recreationally.

Stock Status

Winter Flounder

The 2015 GOM stock assessment update indicates overfishing is not occurring and the stock biomass is unknown. The 2015 SNE/MA stock assessment update indicates 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, and 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, 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.

Atlantic Coastal Management

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 (2005) and Addendum I (2009) are designed to protect spawning females migrating to inshore spawning grounds because they are easily located and caught when congregated for spawning. 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.

Based on the results of the 2008 benchmark stock assessment, which estimated the SNE/MA stock at 9% of the target biomass, the Winter Flounder Management Board (Board) initiated Addendum I, the Secretary of Commerce prohibited retention of SNE/MA 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, which would result in increased discard mortality and loss of fishery-dependent data, the Commission opted to establish bycatch-only possession limits for the SNE/MA stock. Addendum I limits recreational fishermen to 2 fish and commercial fishermen can land a maximum of 50 pounds (or 38 fish) in the SNE/MA; these regulations remain in place today. Addendum I also required states to reduce GOM recreational fishing mortality by 11% and established a 250 pound commercial trip limit.

Board approved Addendum II (2012) to modify the commercial and recreational management requirements for the GOM 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 GOM state waters’ fisheries until June 1, 2013. In May 2013, the Board passed Addendum III for the GOM and SNE/MA 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.

The Board maintained existing management measures for the inshore waters of GOM and SNE/MA for the 2017 fishing season (May 1, 2017 – April 30, 2018). Given management measures have been consistent in recent years, the Board intends to approve a three-year specifications package for winter flounder when the 2019-2021 specifications package becomes available.

Meeting Summaries & Reports