Just like people, fish require suitable shelter and adequate food to survive. Winter flounder spend several important parts of their lives in estuaries – estuaries provide spawning areas for adults, nursery habitat for juveniles, and feeding grounds for both juveniles and adults. These nearshore environments are especially vulnerable to impacts from human activities on land. Because winter flounder are so dependent on healthy nearshore habitat, declines in water quality and habitat loss have taken a toll on their populations. In turn, this habitat degradation has impacted the commercial and recreational fisheries that depend on this resource. NOAA Fisheries’ Office of Habitat Conservation works to restore and protect healthy coastal habitat to support the resources and fisheries that depend on it.
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LAUNCH THE MAPWinter Flounder
Pseudopleuronectes americanus
ALSO KNOWN AS:
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Flounder, Sole, Lemon Sole, Georges Bank Flounder, Blackback Flounder
SOURCE:
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U.S. wild-caught from Maine to Virginia
STATUS
- POPULATION
- FISHING RATE
- HABITAT IMPACTS
- BYCATCH
Click the icons to learn more about each criteria
OVERVIEW
Winter flounder are an important commercial and recreational fish throughout New England and the Mid-Atlantic, although current harvests are a fraction of their historic levels. Heavy fishing pressure and habitat destruction caused winter flounder stocks to drastically decline. Strict fishing regulations are now in place, but it's estimated that it could take more than a decade for winter flounder to regain its earlier abundance off of the East Coast.
The Southern New England/Mid-Atlantic winter flounder stock is at an all-time low. Recent scientific data indicate that previous assessments significantly overestimated the abundance of this stock, leading managers to believe that it was healthier than it actually was. Managers immediately responded to this new information, prohibiting harvest of Southern New England winter flounder in all fisheries. The latest science indicates that this stock’s abundance has increased slightly in the past couple years and is now at 16 percent of target population levels (up from 9 percent in 2008). This is a perfect example of the importance of continued monitoring and active management of our fish stocks and fisheries. Scientists are always learning new things about fish populations, and managers must constantly and routinely adapt to new scientific information.
The Georges Bank winter flounder stock is no longer considered overfished and, under strict management measures, is rebuilding to sustainable levels (currently at 82 percent of the target population level). The results of latest assessment for Gulf of Maine winter flounder were highly uncertain, so scientists weren’t able to determine the population status for this stock. However, they did determine that fishing rates in recent years have been well within the sustainable level. As a result, managers were able to double the amount of Gulf of Maine winter flounder commercial fishermen can catch for the 2011/2012 fishing season, which is good news for fishermen.
LOCATION & HABITAT
Winter flounder are found in estuaries and on the continental shelf of the Northwest Atlantic, from the Gulf of St. Lawrence, Canada to North Carolina. They’re most common north of Delaware Bay.
They’re named winter flounder because of their migrations – in the winter, adults migrate from offshore areas where they feed to inshore bays and estuaries where they spawn. While inshore, they live on muddy sand, clean sand, clay, and pebbly or gravelly bottom habitats. They often bury their whole body, except for their eyes, in bottom sediments. Winter flounder larvae and some 1-year-olds live in the estuaries where they were born. Juveniles prefer sand or sand-silt bottoms in a wide range of salinity and temperature.
BIOLOGY
Winter flounder live 15 to 18 years and grow up to over 2 feet in length. They spawn during the winter and spring in shallow inshore waters, often returning to the same areas where they were born to spawn. Females usually produce between 500,000 and 1.5 million eggs. They deposit their eggs on sandy bottoms and algal mats at night, usually about 40 times every spawning season. Newly hatched larvae have one eye on each side of the head. Five to six weeks after they hatch, larvae settle to the bottom to begin their transformation into juveniles. After weeks of adapting to living on the bottom, their left eye migrates to the right side of their body and their metamorphosis is complete. The growth and survival rates of larvae and juveniles depend on several factors, including temperature, salinity, water quality, and the availability of food.
Winter flounder feed during the day because they depend on sight to locate prey. Their small mouths limit what they can eat. They feed on small invertebrates, shrimp, clams, and worms. Fish (mainly striped bass, bluefish, toadfish, and summer flounder), birds, invertebrates, winter skate, and marine mammals prey on larval and juvenile winter flounder. Atlantic cod, spiny dogfish, and monkfish prey on adults.
PHYSICAL DESCRIPTION
Winter flounder have an oval shape and a thick body. Their eyes are on the right side of their body. They have a straight lateral line and dark coloring. Their coloring often varies with their habitat, ranging from muddy to slightly reddish brown, olive green, or dark slate, to an almost black upper. Their underside is white, and their dorsal and anal fins are often tinged with pink, red, or yellow.
OVERVIEW
Scientists at NOAA’s Northeast Fisheries Science Center conduct bottom trawl surveys every year during the fall and spring in inshore and offshore areas off the northeast coast to assess and monitor the abundance of winter flounder and other species. Managers use this data, along with information from state agency and university-run surveys, to determine the status of the winter flounder population.
In U.S. waters, winter flounder is assessed and managed as three stocks: Georges Bank, Gulf of Maine, and Southern New England/Mid-Atlantic Bight.
POPULATION STATUS
Scientists assessed the winter flounder stocks in 2011. In Georges Bank, spawning stock biomass (a measure of the amount of winter flounder in the population that can reproduce) has been increasing since 2005 and is now at around 82 percent of the target level. This stock continues to rebuild – it is no longer overfished and fishing rates are sustainable.
The Gulf of Maine stock is the smallest of the three winter flounder stocks. The results of the latest assessment were highly uncertain, and scientists were unable to determine an abundance estimate for this stock. However, they were able to determine that fishing rates were sustainable (no overfishing).
The Southern New England/Mid-Atlantic stock has increased since the last assessment, up to 16 percent of the target population level (from 9 percent in 2008). The stock remains overfished, but harvest of fish from this stock is prohibited.
ADDITIONAL RESEARCH
Research 
has indicated that winter flounder is an excellent candidate for stock enhancement, in which juvenile fish hatched from wild brood stock are raised in captivity and released into the wild. Scientists now know how to raise winter flounder and have learned how to release them in a way that maximizes their survival in the wild. Current research is focusing on understanding their impact on the wild population. Fishermen, scientists, members of the aquaculture industry, and fisheries managers are all collaborating in this research to find ways to protect and enhance winter flounder and its fishery.
Harvesting Winter Flounder
U.S. fishermen harvest winter flounder with otter trawls and sink gillnets as part of the large mesh groundfish fishery along the northeast coast. Winter flounder are usually found on soft bottoms, which are more resilient to trawling than other, more sensitive habitats such as corals. Certain areas are also closed to fishing to protect sensitive habitats and species. Gillnets have minimal impact on habitat.
Fishermen are required to use nets with mesh large enough to allow undersized winter flounder and other groundfish to escape. Gillnets and trawls can incidentally catch marine mammals, but fishermen follow a number of mandatory and voluntary measures under the Harbor Porpoise and Large Whale Take Reduction Plans to reduce bycatch of these species. Mandatory measures include gear modifications, seasonal closures, and a requirement to have acoustic alarms on nets to deter harbor porpoises from getting entangled in gillnets. Voluntary measures include reducing the amount of turns made by the fishing vessel and tow times while fishing at night, and increasing communication between vessels about the presence of marine mammals in an area. At-sea fishery observers monitor bycatch in the groundfish fishery.
Management
Who’s in charge? State and federal authorities cooperate in the management of this resource because winter flounder migrate from offshore habitats in federal waters to inshore habitats in state waters to reproduce, and they are harvested in both areas. The Atlantic States Marine Fisheries Commission coordinates management in state waters and the New England Fishery Management Council is responsible for federal waters. NOAA Fisheries is responsible for monitoring winter flounder stocks and implementing and enforcing the management measures developed by the Commission and Council.
Current management:
Offshore: Northeast Multispecies Fishery Management Plan as part of the large-mesh multispecies group
- A limit on the amount of all groundfish that can be caught as well as measures to respond if the catch limit is exceeded.
- No commercial fishing vessel is permitted to land Southern New England winter flounder.
- Optional catch share program – fishing vessels may fish together in groups (sectors), which are established annually and are allotted a portion of the total available groundfish catch, based on the combined fishing history of sector member vessels. Sectors are exempt from many gear and area restrictions but must stop fishing for groundfish once the sector catches their allotment of fish. This allows fishermen more control over where and how they fish and the ability to target healthier stocks rather than overfished stocks. Fishermen who choose not to join a sector must fish under the existing system of regulations, with limits on the number of days they can fish, amount they can catch, and when and where they can fish.
Inshore: Fishery Management Plan for Inshore Stocks of Winter Flounder
State agencies have set minimum size limits and seasonal, area, or state-wide commercial harvest and fishing gear restrictions.
Annual Harvest
In the Gulf of Maine, commercial landings averaged 300 metric tons in the past few years but recently declined to 193.5 metric tons in 2010.
In Georges Bank, commercial harvests mainly come from the U.S. bottom trawl fleet, but Canadian groundfish trawl fisheries have also reported some landings from this area. In the past two decades, landings have averaged 1,950 metric tons. In 2010, they were slightly below this average at about 1,530 metric tons.
In the Southern New England/Mid-Atlantic area, fishermen are prohibited from landing winter flounder. However, some is still caught as bycatch and is discarded at sea. These discards are counted toward the annual catch.
Economy
The 2010 harvest of winter flounder was valued at nearly $7 million.
Recreational
Recreational fishermen also fish for winter flounder, mainly in state waters (out to 3 miles offshore). The recreational fishery accounts for about 10 percent of the annual harvest. There is a 60-day recreational fishing season, and fishermen may only harvest winter flounder with certain gear. They may only keep winter flounder that are the established minimum size or larger.
OVERVIEW
There are hundreds of flatfish species found around the world. The most the most commercially important family of flatfish is Plueronectidae, which is concentrated in northern waters. Winter flounder is member of this family.
Raw flounder ranges in color from tan to pinkish to snow white; cooked flounder is pure white. The meat is lean, boneless, and flaky with a mild flavor. Winter flounder’s sweet taste and firm texture is often the standard to which other flounders are compared. (From Seafood Business, 2011 )
SEASONAL AVAILABILITY
Year-round
NUTRITION
Flounder is a good, low-fat source of B vitamins and an excellent source of niacin.
| Servings | 1 |
| Serving Weight | 100 g (raw) |
| Calories | 91 |
| Protein | 18.84 g |
| Fat, total | 1.19 g |
| Saturated fatty acids, total | 0.283 g |
| Carbohydrate | 0 g |
| Sugars, total | 0 g |
| Fiber, total dietary | 0 g |
| Cholesterol | 48 mg |
| Selenium | 32.7 mcg |
| Sodium | 81 mg |
Winter Flounder Table of Nutrition
