Greenland Turbot (Reinhardtius hippoglossoides)

• Greenland turbot populations are healthy; no overfishing is occurring.
• This fishery is being carefully monitored due to recent declines in the numbers of juvenile fish.
• Greenland turbot is a healthy, low-fat source of protein and is high in omega-3 fatty acids. For more information, see Nutrition Facts. (USDA)
• The dominant gear used to catch Greenland turbot is longline, and most Greenland turbot sold in the U.S. comes from U.S. waters.

Sustainability Status

Biomass: Bering Sea/Aleutian Islands (BSAI) biomass is 74% above the biomass needed to support maximum sustainable yield (B_MSY); Gulf of Alaska (GOA) biomass (Dover sole) is 124% above B_MSY.*
Overfishing: No
Overfished: No
Fishing and habitat: Greenland turbot are primarily harvested with bottom trawl gear fishing on sand and mud habitats. Greenland turbot are also harvested with long line gear, which has little impact on fish habitat.
Bycatch: Possible halibut and seabird bycatch is closely monitored by NOAA's extensive at-sea observer program. For more information, see longlines in the Fisheries Gear section.
Aquaculture: There is currently no aquaculture of Greenland turbot in the U.S.

*GOA biomass is based on status of Dover sole as it is the indicator species for the Deepwater Flatfish Complex in the Gulf of Alaska. No specific biomass estimates are available for GOA Greenland turbot.

Science and Management

In Alaska, Greenland turbot are managed through the North Pacific Fishery Management Council's Fishery Management Plans (FMP) for Groundfish of the Bering Sea/Aleutian Islands (BSAI) and Gulf of Alaska (GOA). The BSAI FMP was first implemented in 1982 and has been amended over 70 times. The original GOA FMP was implemented in 1978 and has been amended over 60 times. The focus of both FMPs has changed from management of foreign fisheries to domestic fisheries, as the groundfish resources off Alaska have been harvested and processed entirely by U.S.-flagged vessels since 1991.

In the BSAI management area, Greenland turbot and arrowtooth flounder were managed together until 1985 when the Council recognized the need for separate management quotas due to differences in the market value and abundance trends between these two species. The fishery is controlled through permits and limited entry, catch quotas (TACs), seasons, in-season adjustments, gear restrictions, closed waters, bycatch limits and rates, allocations, regulatory areas, record keeping and reporting requirements, and observer monitoring. Flatfish as a whole are lightly harvested, primarily due to halibut and crab bycatch limits which frequently close down the fisheries prior to the achievement of TAC. Also, the Council frequently sets conservative quotas for these fisheries because they are unlikely to achieve their TACs and OY can instead be set for more highly valued species. Beginning in 1998, no halibut bycatch was apportioned to the trawl fishery for Greenland turbot, and consequently, no directed turbot fishing has been allowed with trawl gear.

In the GOA Groundfish FMP, Greenland turbot are managed as part of the Deepwater Flatfish complex, along with Dover sole and deep-sea sole. Prior to 1990, the "flatfish" complex managed as a unit, but the NPMFC later divided the unit into 4 separate categories based on halibut bycatch rates in directed fisheries, market value, abundance, and distribution. The fishery is currently managed with permits and limited entry, catch quotas (TACs), seasons, in-season adjustments, gear restrictions, bycatch limits and rates, allocations, regulatory areas, record keeping and reporting requirements, and observer monitoring. In 1998, trawling was prohibited in part of the Eastern area. Harvests have also been constrained by halibut bycatch limits.

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. Knowing that current biomass is at low levels due to poor recruitment in the BSAI management area, managers have set low total allowable catch (TAC) levels for Greenland turbot as a conservation measure. Research is also being conducted to further determine reasons for the smaller stock size.

• Geographic range: Throughout the eastern Bering Sea and Aleutian Islands region; also widely distributed in the Northwest Atlantic
• Habitat: Greenland turbot live near the ocean floor. Juveniles spend the first 3 or 4 years of life on the continental shelf then move to the continental slope and are absent in the Aleutian Islands regions. Adults are located in the lower and middle portion of the water column (328 to 3,280 feet) along the outer shelf, upper slope, and lower slope. Turbot prefer cold temperatures and softer substrates consisting of mud and sandy mud.
• Life span: 21 years
• Food: Crustaceans, squid, and a variety of fish species
• Growth rate: Relatively fast growing
• Maximum size: About 25 pounds
• Reaches reproductive maturity: Females mature at about 2 feet long and 9 years old.
• Reproduction: Females produce about 60,000 to 80,000 eggs. They release the eggs, and males swim by and fertilize them. But then, unlike most fish, the Greenland halibut larvae begin to drift out of the deep ocean into shallower waters hundreds of miles away.
• Spawning season: Winter
• Spawning grounds: Near the bottom in deep waters, more than 1000 feet. The absence of juveniles in the Aleutian Islands suggests that the population originates from the eastern Bering Sea or elsewhere.
• Migrations: Unknown
• Predators: Greenland turbot are the primary winter prey of narwhals. Other predators include Pacific cod and halibut.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: Flatfish; one eye migrates across the top of its skull toward the other eye during one of its larval stages

Role in the Ecosystem

In the BSAI management area, juvenile Greenland turbot abundance has declined on the eastern Bering Sea (EBS) shelf region, compared to observations during the late 1970s. The high level of abundance during the late 1970s may have been unusual, and the current level may be typical for Greenland turbot life history pattern. Several major predators on the shelf were at relatively low stock sizes during the late 1970s (Pacific cod, Pacific halibut) but increased to peak levels during the mid 1980s. Perhaps this shift in abundance reduced the survival of juvenile Greenland turbot in the EBS shelf. On the other hand, changes in abundance may be due to shifting oceanographic conditions over the years. Without further information on where different life stages are currently residing, researchers and managers can only speculate on the likelihood of this scenario. Currently, the ecosystem group within the Resource Ecology and Fisheries Management Division of the Alaska Fisheries Science Center is evaluating the pattern of mortality among different species in the EBS. One aspect of this work involves developing a multi-species model. Results from this work indicate that Greenland turbot has been an important predator.

Additional Information

Market name: Turbot
Vernacular name: Newfoundland turbot, Turbot, Blue halibut
Several other species are marketed with the name Turbot.

Biomass

Biomass refers to the amount of Greenland turbot 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. Scientists and managers can then make appropriate changes in the regulations of the fishery.

Unlike biomass of other BSAI flatfish, biomass of Greenland turbot is at low levels and declining, due to poor year classes from 1981 to 1997. Since the 1990s, NPFMC has set low total allowable catch (TAC) levels (7,000 metric tons/15.4 million pounds or lower) for Greenland turbot as an added conservation measure due to concerns about low recruitment. Despite this control, biomass is projected to continue declining.

Note: BSAI biomass only includes turbot age 1 year and older. Biomass estimates are not presented for the Gulf of Alaska because Greenland turbot are not as abundant there and estimates are unreliable.

Landings

Landings refer to the amount of catch that is brought to land. Catches of Greenland turbot and arrowtooth flounder were not reported separately during the 1960s. The Greenland turbot fishery intensified in the 1970s, reaching peak landings from 1972 to 1976 between 63,000 and 78,000 tons (138.9 million and 172 million pounds) annually. Since 1983, harvests have declined steadily mainly due to catch restrictions placed on the fishery because of declining recruitment.

Note: The landings presented are domestic commercial landings.

Biomass and Landings

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

Data sources:
Biomass from 2007 Assessment of Greenland Turbot in the Eastern Bering Sea and Aleutian Islands

Landings from NOAA's National Marine Fisheries Service (NMFS) Annual Commercial Landings using "HALIBUT, GREENLAND" as Species and "ALASKA" as State

Important Dates

1960s – Annual catches of Greenland turbot average about 30,000 metric tons (66 million pounds) in the Bering Sea/Aleutian Islands (BSAI) area
1970s – Greenland turbot fishery intensifies
1972-1976 – Turbot fishery peaks between 63,000 and 78,000 tons (138.9 million and 172 million pounds) annually
1978 – Gulf of Alaska (GOA) Groundfish FMP implemented
1982 – BSAI Groundfish FMP implemented
1983 – Harvests declined steadily, mainly due to catch restrictions placed on the fishery because of declining recruitment
1986 to present – BSAI landings remain at or below 10,000 metric tons (22 million pounds)
1992-1997 – North Pacific Fishery Management Council (NPFMC) sets BSAI total allowable catch (TAC) levels to 7,000 tons (15.4 million pounds) as an added conservation measure due to concerns about apparent low levels of recruitment in the past several years; results in primarily bycatch-only fisheries
1996 – Trawl gear effectively prohibited from targeting turbot in the BSAI, as no halibut bycatch has been apportioned for a directed trawl fishery
1998 – Trawl gear prohibited in the eastern GOA

Notes and Links

General Information:
Groundfish of the Bering Sea and Aleutian Islands Area: Species Profiles 2001

Groundfish of the Gulf of Alaska: A Species Profile 1998 (Deep Water Flatfish)

Fishery Management:
Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (2006)

Fishery Management Plan for Groundfish of the Gulf of Alaska (2006)

Stock Assessments:
2007 Assessment of Greenland Turbot in the Eastern Bering Sea and Aleutian Islands

2007 Gulf of Alaska Deepwater Flatfish Assessment