Summer Flounder

Life History

Summer flounder (Paralichthys dentatus) are found in inshore and offshore waters from Nova Scotia, Canada to the east coast of Florida. In the U.S., they are most abundant in the Mid-Atlantic region from Cape Cod, Massachusetts to Cape Fear, North Carolina.

Summer flounder usually begin to spawn at age two or three, at lengths of about 10 inches. Spawning occurs in the fall while the fish are moving offshore. Spawning migration is linked to sexual maturity, with the oldest and largest fish migrating first. As in their seasonal migrations, spawning summer flounder in the northern portion of the geographic range spawn and move offshore (depths of 120 to 600 feet) earlier than those in the southern part of the range. Larvae migrate to inshore coastal and estuarine areas from October to May. The larvae, or fry, move to bottom waters upon reaching the coast and spend their first year in bays and other inshore areas. At the end of their first year, some juveniles join the adult offshore migration.

Adults spend most of their life on or near the sea bottom burrowing in the sandy substrate. Flounder lie in ambush and wait for their prey. They are quick and efficient predators with well-developed teeth allowing them to capture small fish, squid, sea worms, shrimp, and other crustaceans.

Commercial & Recreational Fisheries

Summer flounder are one of the most sought after commercial and recreational fish along the Atlantic coast, with total landings at approximately 17.4 million pounds in 2014. Using baseline data from 1980 to 1989, the current plan allocates the summer flounder quota on a 60/40 percent basis to commercial and recreational fisheries, respectively.

Two major commercial trawl fisheries exist — a winter offshore and a summer inshore. Summer flounder are also taken by pound nets and gillnets in estuarine waters. Throughout the 1980s, commercial landings ranged from 21 to 38 million pounds. By 1990, landings reached a low of nine million pounds and have since fluctuated between nine and 17 million pounds. In 1993, the coastwide quota was implemented for the first time, setting a commercial landings limit of 12.35 million pounds. Commercial quotas have since ranged from 9.46 to 18.18 million pounds. Commercial landings (which are limited by the quota) have ranged from 8.81 million pounds to 18.17 million pounds since 1993. 2014 commercial landings were estimated at 10.9 million pounds.

Summer flounder are also highly prized in the recreational fishery. Anglers catch summer flounder from the shore, piers, and boats with hook and line. From 1980 through 2004, recreational landings varied widely from a high of 38 million pounds in 1980 to a low of three million pounds in 1989. Starting in 1993, harvest limits were implemented for the recreational fishery. From 1993 to 2011, landings ranged from 5.1 to 16.5 million pounds. 2014 recreational harvest was estimated at 7.4 million pounds.

Although reported landings have equaled or only slightly exceeded commercial quotas and recreational harvest limits in recent years, there is evidence of substantial illegal harvest in the form of unreported, underreported, or misreported landings. In 2013 and 2014, two separate investigations revealed that large quantities of summer flounder were being taken illegally under the guise of quota acquired through the Council’s Research Set-Aside (RSA) program (the Council subsequently suspended the program in order to consider alternative cooperative research options). There may also be substantial non-RSA related illegal/unreported landings, although fewer details are available on the extent of unreported landings outside of the RSA program. While the exact amount of illegally harvested summer flounder is not known, the effect may have resulted in substantial overages of the fishery’s annual catch limits (ACLs).

Stock Status

The 2016 stock assessment update indicates the summer flounder stock is not overfished but is experiencing overfishing. Fishing mortality exceeded its threshold by 26% (i.e., the level beyond which overfishing is occurring). The 2015 estimate of spawning stock biomass (SSB) is at 58% of the biomass target, and only 16% above the threshold. These results appear to be driven largely by below-average recruitment, as the assessment update indicates that the stock experienced six years of below average year classes from 2010 to 2015. Additionally, indices of abundance from state and federal surveys have indicated declines in abundance ranging from 9 to 97% from their most recent peaks (generally 2009 to 2012). The 2016 assessment update estimated biomass has been trending down since 2010.

The Commisison and the Mid-Atlantic Fishery Management Council approved an acceptable biological catch (ABC) limit of 16.26 million pounds for the 2016 fishing season, an approximate 29% decrease from 2015. After accounting for projected discards in the commercial and recreational fisheries, this ABC is divided into a commercial quota of 8.12 million pounds and a recreational harvest limit of 5.42 million pounds for the 2016 fishing year.

Atlantic Coastal Management

Recreational angler with summer flounder. Photo credit: Mark Terceiro, NMFS NEFSC.

The Commission approved the first Fishery Management Plan (FMP) for Summer Flounder in 1982, followed by a similar FMP approved by the MAFMC in 1988. Since then, both agencies have made significant revisions to the plan, increasing the protection of juvenile fish and ensuring the maintenance of an adequate spawning population. This increased protection was achieved through the implementation of larger minimum size limits across all sectors, increased mesh sizes, and decreased recreational possession limits. Cumulatively, these changes have contributed to rebuilding the resource. This is not to say that challenges in managing this species do not still exist. Issues related to sector allocation and annual harvest levels persist.