Scientists are concerned about the impact of climate change on flathead sole stocks, particularly in the Bering Sea. In this area, flathead sole at the northern edge of its range overlaps and competes with its smaller cousin Bering flounder (H. robustus) at the southern edge of its range. Warming temperatures in the eastern Bering Sea could allow flathead sole to extend its range further north, potentially increasing competition with Bering flounder (unless that species also is forced further north by warming temperatures).
- Ocean perch
- Sea Bass
- Turbot (Greenland)
ALSO KNOWN AS:
Sole, Flounder, Flathead Flounder, Halibut-like Flounder
U.S. wild-caught mainly from Alaska, but sometimes off Oregon
- FISHING RATE
- HABITAT IMPACTS
Click the icons to learn more about each criteria
Flathead soleLAUNCH GALLERY
Flathead sole is not true sole (which is found only in the Atlantic), but is related more closely to flounder. Foreign fleets historically harvested flathead sole from the 1960s through the 1980s. Today, Alaska fishermen catch almost all of the commercial harvest of this delicate, mild-tasting fish. A very small amount is also harvested off the West Coast (mainly Oregon. Markets for flathead sole were limited in the past but are growing. The primary products are headed and gutted fish with roe-in, as well as kirimi (fish slices).
Scientists actively monitor the abundance of flathead sole in both the Bering Sea and Aleutian Islands region and the Gulf of Alaska. Managers use the latest estimates of abundance to set sustainable harvest limits for the next fishing season. Catch is monitored throughout the season to ensure it doesn’t exceed harvest limits or limits on bycatch of prohibited species (halibut, salmon, and crab).
LOCATION & HABITAT
Flathead sole are found from Alaska south along the west coast of North America to northern California. Flathead sole eggs and larvae float near the surface, until they change form and settle to the bottom. Young flathead sole grow and develop in shallow estuaries, bays, and nearshore coastal areas along the northern Pacific coast. Flathead sole live on mixed mud and sand bottoms 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.
Flathead sole grow up to 1.8 feet and can live up to at least 34 years. They’re 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 in February through April in deeper waters on the edge of the continental shelf. Depending on their size, females release 72,000 to 600,000 eggs. The eggs are large and are fertilized externally. They 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, pollock, and arrowtooth flounder prey on flathead sole.
Flathead sole has an oval-shaped, compressed body. It is a right-eyed flatfish – its left eye migrates over to the right side during development. Their eyed side is dark olive brown to reddish gray-brown, sometimes with dusky blotches. Their blind side (the underside) is white. Their dorsal and anal fins have dusky blotches.
NOAA’s Alaska Fisheries Science Center conducts bottom trawl surveys every year on the continental shelf in the Eastern Bering Sea and every 2 years in the Gulf of Alaska to monitor the abundance of flathead sole and other groundfish. They conduct full stock assessments every year for the Bering Sea/Aleutian Islands stock and every 2 years for the Gulf of Alaska stock to help managers set harvest limits and make other management decisions.
Flathead sole is quite abundant in both the Gulf of Alaska (146 percent above target population levels) and Bering Sea and Aleutian Islands areas (85 percent above target).
Scientists continue to research the principal drivers of recruitment for flathead sole in the eastern 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 remains unclear.
Harvesting Flathead Sole
Almost all of the U.S. commercial harvest of flathead sole comes from Alaska, mainly the Bering Sea and Aleutian Islands area. Here, fishermen primarily use bottom trawls to harvest flathead sole. About 30 percent of the harvest is caught with pelagic trawls. Bottom trawlers tow a cone-shaped net along the bottom; pelagic trawls tow the net through the water column. Fisheries mainly operate from January through June.
In the Gulf of Alaska, fishermen use bottom trawls to harvest flathead sole and mainly fish from January through November. Flathead sole are also harvested incidentally in fisheries for Pacific cod, pollock, and other flatfish in both areas.
Who’s in charge? NOAA Fisheries and the North Pacific Fishery Management Councils
Current management: Bering Sea and Aelutian Islands and Gulf of Alaska Groundfish Fishery Management Plans
In Alaska, flathead sole fisheries are managed separately, but similarly, in the Bering Sea and Aleutian Islands and in the Gulf of Alaska. Fishermen must have a permit to participate in these fisheries, and the number of available permits is limited to control the amount of fishing. Every year, managers determine how much flathead sole can be caught. In the Bering Sea and Aleutian Islands, this catch quota is allocated among fishermen active in the directed flathead sole fishery. Catch is monitored through recordkeeping, reporting requirements, and observer monitoring.
Only a small amount of flathead sole is harvested incidentally in groundfish fisheries operating off the West Coast. The Pacific Fishery Management Council has included the species in the Pacific Coast Groundfish Fishery Management Plan, but it is not assessed or directly managed.
In the Bering Sea and Aleutian Islands area, annual catches have increased since the 1990s, averaging nearly 18,000 tons. Higher catches can be attributed to higher incidental catch in other fisheries as well as emerging markets for flathead sole. In the past, fishermen threw back about a third of the flathead sole they caught both incidentally in other fisheries and in the directed flathead sole fishery. Since 2008, only 10 percent has been discarded due to new regulations that require lower discard rates among participating fishing vessels.
In the Gulf of Alaska, annual catches have increased steadily, from lows in the mid-1980s to over 3,800 metric tons in 2010. Fishermen retain over 90 percent of their flathead sole catch in this area.
In 2010, flathead sole products from the Bering Sea were valued at almost $14 million, while products from the Gulf of Alaska were valued at $3 million. In the Bering Sea, headed and gutted products accounted for over 93 percent of the total value. In the Gulf of Alaska, headed and gutted products accounted for 79 percent of the total value; whole fish products accounted for 18 percent.
The only gears authorized for recreational fishing are hook-and-line and spear. Bag limits on the number of fish that can be caught vary by state.
Larger than many of the other Pacific soles, flathead soles have firm white meat and thicker fillets, and they most closely resemble the true European sole. Sole have a delicate, mild flavor. Flathead sole are mainly sold headed and gutted and as kirimi (fish slices).
Flathead sole is an excellent source of low-fat protein, calcium, and other important nutrients.
|Serving Weight||100 g (raw)|
|Fat, total||1.19 g|
|Saturated fatty acids, total||0.283 g|
|Sugars, total||0 g|
|Fiber, total dietary||0 g|
Flathead sole table of nutrition
- Coming Soon...