Arrowtooth Flounder (Atheresthes stomias)

• Arrowtooth flounder populations are very healthy, and no overfishing is occurring.
• The arrowtooth fishery off the West Coast is limited by market demand and bycatch limits for rockfish. In Alaska, arrowtooth are typically only caught incidentally in fisheries targeting other species; catch is also limited by market demand and halibut bycatch caps.
• Flounder is a good, low-fat source of B vitamins and an excellent source of niacin. For more on nutrition, see Nutrition Facts. (USDA)
• If not properly handled, the flesh of arrowtooth flounder can soften, lowering its value and marketability. As a result, fishermen often try to avoid this species, especially in Alaska. To make it more marketable, arrowtooth is usually sold on the West Coast as turbot, although it is not related to the true turbot (Psetta maxima), which is a very highly valued commercial species.

Sustainability Status

Biomass: West Coast biomass is well above the biomass needed to support maximum sustainable yield (B_MSY), at 97 percent above B_MSY. In the Gulf of Alaska, biomass is 198% above B_MSY. In the BSAI, biomass is three times the B_MSY value.
Overfishing: No
Overfished: No
Fishing and habitat: Off the West Coast, arrowtooth flounder is caught by bottom trawl gear, including a specialized bottom trawl gear called selective flatfish trawl gear. Trawling involves the towing of a funnel shaped net or nets behind a fishing vessel. Trawl gear may be fished on or near the bottom. A bottom trawl is a trawl in which the doors, the footrope of the net, or both are in contact with the seabed. There is no directed fishery in Alaska so there is no impact on habitat.
Bycatch: Off the West Coast, arrowtooth is caught with a selective flatfish trawl net which is configured with a cut back headrope, low rise, and a small footrope, a design shown to substantially reduce catches of some rockfish species while more efficiently catching target flatfish species. However, some rockfish, including canary rockfish (an overfished groundfish species), and halibut are caught as bycatch in the arrowtooth flounder fishery. In Alaska, arrowtooth are not a targeted fishery so there is no bycatch.
Aquaculture: There is currently no commercial aquaculture of arrowtooth flounder in the U.S.

Science and Management

Off the West Coast, arrowtooth flounder are managed by the Pacific Fishery Management Council through the Pacific Coast Groundfish Fishery Management Plan. In general, groundfish are managed through a number of measures including harvest guidelines, quotas, trip and landing limits, area restrictions, seasonal closures, and gear restrictions. All sectors of the groundfish fishery are currently limited by the need to rebuild groundfish species that have been declared overfished.

NMFS implemented the Groundfish Vessel Buyback Program in 2003 to reduce the number of vessels and permits fishing for groundfish off the West Coast. This program aims to increase productivity of the fishery, help financially stabilize the fishery, and conserve and manage fish.

In 2003, the Pacific Fishery Management Council also began using depth-based management for commercial and recreational groundfish fishing in order to avoid overharvest. Depth-based management means that some depth zones are closed to fishing. Because this can be difficult to enforce, managers are implementing vessel monitoring systems (VMS) to determine if a vessel is fishing in a closed area. Read more about VMS here, too.

Fishermen try to avoid arrowtooth in Alaska because of its low commercial value. However, it is still managed under the Gulf of Alaska (GOA) Groundfish FMP because of its importance to the GOA ecosystem and potentially growing commercial interest. Arrowtooth is also included in the Bering Sea and Aleutian Islands Groundfish FMP although there is currently not a directed fishery for the species.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed.

• Geographic range: Arrowtooth flounder are found from Northern California through the Bering Sea. It is the dominant flounder species on the outer continental shelf from the western Gulf of Alaska to Oregon.
• Habitat: Eggs and larvae are pelagic; juveniles and adults are found on the ocean bottom. Juveniles and adults are most commonly found on sand or sandy gravel substrates and occasionally over low-relief rock-sponge bottoms. Arrowtooth flounder can be found in depths of 160 feet in the summer to more than 1,640 feet in the winter.
• Life span: Arrowtooth flounder can live up to 27 years.
• Food: Larvae eat copepods (a type of small crustacean) and their eggs and larvae. Juveniles and adults feed on crustaceans (mainly ocean pink shrimp and krill) and fish (mainly cod, herring, and pollock).
• Growth rate: Slow. Females grow slightly faster than males.
• Maximum size: Females can grow up to 2.8 feet in length; males can grow up to 2 feet in length.
• Reaches reproductive maturity: Males mature at 3 to 7 years and between 12 and 16.5 inches. Females mature at 4 to 8 years and between 14.5 and 16.5 inches.
• Reproduction: Arrowtooth flounder spawn multiple times during a spawning season. They lay eggs which are fertilized externally. The larvae spend approximately 4 weeks in the upper 330 feet of the water column then settle to the bottom in the late winter and early spring.
• Spawning season: Spawning season various by location. Off the West Coast, arrowtooth spawn in the late fall through early spring. In the Gulf of Alaska, spawning occurs during spring and summer. Off the coast of Alaska, arrowtooth flounder spawn between fall and winter.
• Spawning grounds: Off the coast of Washington, arrowtooth flounder spawn in waters deeper than 1,640 feet. In the Bering Sea and Gulf of Alaska, spawning occurs over depths of 360 to 1,180 feet.
• Migrations: Arrowtooth flounder migrate from shallow water on the continental shelf where they feed in the summer to deep water over the continental slope where they spawn.
• Predators: Predators of juvenile arrowtooth include skates, dogfish, shortspine thornyhead, halibut, coastal sharks, orcas, toothed whales, and harbor seals. Adult arrowtooth are likely to be vulnerable only to the largest of these predators.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: Arrowtooth flounder are a relatively large, brownish colored flatfish with a large mouth.

Role in the Ecosystem

Arrowtooth flounder are currently the most abundant fish in the Gulf of Alaska. Because of their abundance, arrowtooth flounder are ecologically important at higher trophic levels in the Gulf of Alaska food web and have been identified as a significant food source for Steller sea lions. Arrowtooth flounder are also known to be voracious predators of juvenile walleye pollock.

Additional Information

Market name: Flounder, Arrowtooth
Vernacular name: Arrowtooth Halibut, Turbot, Paltus

Biomass

Biomass refers to the amount of arrowtooth flounder in the ocean. Scientists cannot collect and weigh every single fish to determine biomass, so they use models to estimate it instead. These biomass estimates can help determine if a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes in the regulations of the fishery.

The West Coast arrowtooth stock was moderately depleted through the 1950s and 1960s but was rebuilt in the late 1970s. Recent strong year classes have led to an increase in the stock since the late 1990s. The stock was last assessed in 2007, and biomass was estimated to be 85,175 metric tons.

Arrowtooth flounder are currently the most abundant fish in the Gulf of Alaska. Biomass (age 3+) increased from 362,688 tons in 1961 to a high of over 2.25 million tons in 2007. In the BSAI, arrowtooth flounder biomass has been increasing since 1975 and currently remains at high levels.

Note: In the graph, BSAI biomass only includes arrowtooth age 1 and older; GOA biomass includes arrowtooth age 3 and older. Total West Coast biomass is shown.

Landings

Landings refer to the amount of catch that is brought to land. Off the West Coast, arrowtooth have likely been unintentionally caught by flatfish trawlers since the inception of the trawl fisheries. They were also caught in large, unselective flatfish fisheries for mink food that operated in Oregon and Washington in the 1950s through 1970s. A targeted fishery for arrowtooth flounder developed in the late 1970s. The fishery has been limited due to market demand, regulations, and bycatch of rockfish. Landings from 1998 to 2006 have varied from a high of 5,285 metric tons in 1999 to a low of 1,918 metric tons in 2006.

Arrowtooth flounder are currently of low value in the GOA, and while some directed fishing for arrowtooth occurs in the GOA, most are discarded. The percent retained has increased from below 10% in the early 1990s to about 57% in 2004. Higher catches in recent years are a result of higher biomass levels and subsequently higher incidental catch in other target fisheries and increased marketing efforts for arrowtooth fish meal and surimi.

In the BSAI, little effort has been directed to catching arrowtooth flounder, and they are taken as bycatch by trawl and longline gear in pursuit of higher valued species and often discarded. However, markets have been developed and fishermen are expected to retain more of this species in coming years. From 1974 to 1976, total catches (including discards) of arrowtooth flounder reached peak levels ranging from 19,000 to 25,000 tons. Arrowtooth flounder has since remained lightly exploited, with catches averaging 12,789 tons from 1977 to 2008. Catch declined due to catch restrictions placed on Greenland turbot and phasing out of the foreign fishery in the U.S. EEZ. Total catch for 2008 was only 21,856 tons, well below the allowable biological catch of 243,900 tons.

Biomass and Landings

Are landings and biomass related? Landings are dependent on biomass, management measures in the fishery, and fishing effort.

Data sources:
Biomass and landings from 2008 BSAI Arrowtooth Flounder Stock Assessment, 2008 GOA Arrowtooth Flounder Stock Assessment, Stock Assessment of the Arrowtooth Flounder Population off the West Coast of the United States in 2007

Important Dates

1950s-1970s – Arrowtooth flounder is caught in large, unselective flatfish fisheries for mink food in Oregon and Washington; stock is moderately depleted
1970s – A targeted fishery for arrowtooth flounder develops off West Coast; stock rebuilds
1978 – GOA Groundfish FMP is implemented
1982 – Pacific Coast Groundfish FMP is approved and implemented
1982 – BSAI Groundfish FMP is implemented
Prior to 1986 – In BSAI, arrowtooth flounder is managed with Greenland turbot
1986 to present – BSAI arrowtooth flounder separated into single species management
Prior to 1990 – GOA arrowtooth flounder managed within flatfish complex
1990 to present – GOA arrowtooth flounder separated into single species management
1990s – Strong year classes off West Coast; arrowtooth flounder stock increases
2003 – Groundfish Vessel Buyback Program is implemented for West Coast
2003 – Pacific Fishery Management Council begins using depth-based management for commercial and recreational groundfish fisheries

Notes and Links

General Information:
Pacific Fishery Management Council's Backgrounder on Groundfish

Northwest Regional Office Groundfish Fishery Management

Groundfish of the Bering Sea and Aleutian Islands Area: Species Profiles

Groundfish of the Gulf of Alaska: A Species Profile

Alaska Fisheries Science Center - Arrowtooth Flounder Research

Fishery Management:
Pacific Coast Groundfish Fishery Management Plan

Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands and Appendix

Fishery Management Plan for Groundfish of the Gulf of Alaska and Appendices

Stock Assessments:
2008 BSAI Arrowtooth Flounder Stock Assessment

2008 GOA Arrowtooth Flounder Stock Assessment

Stock Assessment of the Arrowtooth Flounder Population off the West Coast of the United States in 2007