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Flathead Sole

Hippoglossoides elassodon

Flathead sole

Also Known As

  • Sole
  • Flounder
  • Flathead flounder
  • Halibut-like flounder

U.S. wild-caught flathead sole is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.

Population

Above target population levels in Alaska. The population status is unknown off the West Coast.

Fishing Rate

At recommended levels.

Habitat Impacts

Area closures and gear restrictions protect habitats affected by bottom trawls used to harvest flathead sole.

Bycatch

Regulations are in place to minimize bycatch.

  • Availability

    Year-round. 

  • Source

    U.S. wild-caught from Alaska, and sometimes Oregon. 

  • Taste

    Mild and delicate flavor.

  • Texture

    Firm and thick fillets. 

  • Color

    White.  

  • Health Benefits

    Flathead sole is an excellent source of low-fat protein as well as calcium and vitamins. 

The U.S. Fishery

Fishery Management

  • NOAA Fisheries and the North Pacific Fishery Management Council manage this fishery in Alaska.
  • Managed under the Fishery Management Plans for Groundfish of the Bering Sea and Aleutian Islands and Gulf of Alaska:
    • Fishermen must have a permit to participate in the fishery, and the number of available permits is limited to control the amount of fishing.
    • Managers determine how much flathead sole can be caught each year based on assessments conducted in the Bering Sea/Aleutian Islands and Gulf of Alaska.
    • In the Bering Sea/Aleutian Islands a percentage of the allowable catch is allocated to the community development quota program, which benefits fishery-dependent communities in Western Alaska. The rest is allocated under a catch share program to the trawl catcher/processor sector based on historic harvest and future harvest needs to improve retention and utilization of fishery resources by the trawl fleet.
    • In the Gulf of Alaska, total allowable catch is allocated by regulatory area (western, central, and 2 sub-areas of the eastern Gulf of Alaska).
    • Catch is monitored through record keeping, reporting requirements, and observer monitoring.
  • NOAA Fisheries and the Pacific Fishery Management Council manage this fishery on the West Coast.
  • Managed under the Pacific Coast Groundfish Fishery Management Plan:
    • Only a small amount of flathead sole is harvested incidentally in fisheries off the West Coast.
    • Flathead sole is included in the groundfish fishery management plan, but it is not assessed or directly managed. 

Harvest

  • In 2016, landings of flathead sole totaled more than 25 million pounds and were valued at more than $3.6 million dollars.
    • Almost all commercial harvest of flathead sole comes from Alaska, mainly the Bering Sea and Aleutian Islands.
  • Gear types, habitat impacts, and bycatch:
    • Flathead sole are primarily caught with bottom trawls, and some are caught with pelagic trawls.
    • Gulf of Alaska and Bering Sea/Aleutian Islands fishermen use modified trawl gear that reduces the impact of trawling on animals living on the sea floor, including crabs.
    • Halibut, salmon, and crab are incidentally caught in the groundfish fishery in Alaska.
    • There are limits on how much halibut, herring, and crab can be caught incidentally. If this limit is reached, an area or the entire fishery is closed for the remainder of the season.
    • In Alaska and on the West Coast, NOAA Fisheries and the regional fishery management councils have implemented large closed areas to protect sensitive rocky, cold-water coral and sponge habitats from bottom trawls.
  • Recreational fishermen may fish for flathead sole:             
    • Only hook-and-line and spear gear is allowed.
    • Bag limits on the number of fish that can be caught vary by state.

The Science

Population Status

  • According to the 2017 stock assessment, flathead sole in the Bering Sea/Aleutian Islands are not overfished and are not subject to overfishing.
  • According to the 2017 stock assessment, flathead sole in the Gulf of Alaska are not overfished and are not subject to overfishing.
  • Flathead sole are quite abundant in Alaska, and populations are well above target levels.
  • On the West Coast, flathead sole make up only a small percentage of groundfish harvests. Scientists do not formally assess this species so the population status is unknown.
  • Flathead sole are part of the “other flatfish” complex on the West Coast, and are not subject to overfishing based on 2016 catch data.

Location

  • Flathead sole are found from Alaska south along the west coast of North America to northern California.

Habitat

  • Young flathead sole live in shallow estuaries, bays, and nearshore coastal areas along the Pacific coast. 
  • Adults live on mixed muddy and sandy ocean habitats in depths less than 1,000 feet.
  • They migrate from winter spawning grounds along the outer continental shelf to feeding grounds in shallower water in the spring. 

Physical Description

  • Flathead sole have an oval-shaped, compressed body.
  • They are flatfish, with both of their eyes located on the right side of their head.
  • Their upper side is dark olive brown to reddish gray-brown, sometimes with dusky blotches, and their underside is white. 
  • Their dorsal and anal fins have dusky blotches. 

Biology

  • Flathead sole grow up to 1.8 feet and can live at least 34 years.
  • They are able to reproduce at 2 to 3 years old in the southern part of their range, but not until 6 years old in the northern part.
  • Flathead sole spawn from February through April in deeper waters on the continental shelf.
  • Depending on their size, females release 72,000 to 600,000 eggs. Eggs are large and are fertilized externally.
  • Eggs hatch in 9 to 20 days, depending on water temperature.
  • Flathead sole generally feed on bottom-dwelling invertebrates such as crustaceans, mollusks, and brittle stars, as well as fish and squid.
  • Pacific cod, halibut, Alaska pollock, and arrowtooth flounder prey on flathead sole. 

Research

  • Studying bottom-dwelling fishes and crabs of the Eastern Bering Sea Shelf
  • Scientists continue to research the principal drivers of recruitment for flathead sole in the Bering Sea. Recruitment refers to young fish surviving, growing, and “recruiting” to the adult population. Although recruitment has important implications for management of the stock, current evidence for the relative importance of population density and environmental effects on recruitment remain unclear.

Last updated: 09/19/2018