Document
First Results of the Tagging of Shortspine Thornyhead in Alaska
Shortspine thornyhead (Sebastolobus alascanus) is a commercially valuable deep dwelling rockfish…
Shortspine Thornyhead
Shortspine Thornyhead
Sebastolobus alascanus
Also Known As
Thornyhead, Idiot fish, Idiot cod, Rockfish
Quick Facts
Region
Alaska,
West Coast
About the Species
Shortspine thornyhead are found from the Bering Sea to Baja California, Mexico. They are distinguished from other rockfishes by the spiny ridge across their cheek. Shortspine thornyhead can live in depths up to 1,500 meters, though they are more commonly found between 55 and 465 meters.
U.S. wild-caught shortspine thornyhead is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.
Population
Above target population level on the Pacific Coast.
Fishing Rate
At recommended levels.
Habitat Impacts
The trawl, longline, and pot gear used to harvest shortspine thornyhead have minimal or temporary effects on habitat. Area closures and gear restrictions protect sensitive rocky, cold-water coral, and sponge habitats from bottom trawl gear.
Bycatch
Regulations are in place to minimize bycatch of overfished and protected species.
Population Status
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There are three stocks of shortspine thornyhead: Pacific coast, one stock contained in a stock complex in the Gulf of Alaska, and one stock contained in a stock complex in the Bering Sea/Aleutian Islands. According to the most recent stock assessments:
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The Pacific Coast stock is not overfished (2013 stock assessment) and not subject to overfishing based on the 2018 catch data. Summary stock assessment information can be found on Stock SMART.
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The population status of the Gulf of Alaska Thornyhead Rockfish Complex, which includes shortspine thornyhead, is unknown. The complex has not been assessed, but according to 2020 catch data, the complex is not subject to overfishing.
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The population status of Bering Sea/Aleutian Islands Other Rockfish Complex, which includes shortspine thornyhead, has been assessed (2020 stock assessment), but there is not enough information to determine the population size so the population status is unknown. This complex is not subject to overfishing based on 2020 catch data. Summary stock assessment information can be found on Stock SMART.
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Appearance
- Shortspine thornyhead have elongated bodies and large heads.
- They have a strong spiny ridge and 16 dorsal spines.
- They are bright red or orange red in color, and often have white patches on their sides, backs, cheeks and spiny dorsal fin tips when seen underwater.
- Their fins can have black patches and there may be dark spots or speckles on their sides.
Biology
- Shortspine thornyheads grow slowly and may reach lengths up to 80 centimeters.
- They may live 80 to 100 years.
- Females grow larger than males, and reach maturity around 18 centimeters, or 8 to 10 years of age.
- Shortspine thornyhead spawn pelagic, gelatinous masses.
- They spawn between December and May along the West Coast and between April and May in the Gulf of Alaska.
- Shortspine feed on shrimp, crabs, zooplankton, amphipods, and other benthic invertebrates.
Where They Live
- Shortspine thornyhead are found from the Bering Sea to Baja California, Mexico.
Fishery Management
- NOAA Fisheries and the Pacific Fishery Management Council manage the shortspine thornyhead fishery on the West Coast.
- Managed under the Pacific Coast Groundfish Fishery Management Plan:
- Permits and limited entry to the fishery.
- Limit on how much may be harvested in one fishing trip.
- Certain seasons and areas are closed to fishing.
- Gear restrictions help reduce bycatch and impacts on habitat.
- A trawl rationalization catch share program that includes:
- Catch limits based on the population status of each fish stock and divided into shares that are allocated to individual fishermen or groups.
- Provisions that allow fishermen to decide how and when to catch their share.
- NOAA Fisheries and the North Pacific Fishery Management Council manage shortspine thornyhead as part of the thornyhead complex in the Gulf of Alaska (GOA) and the other rockfish complex in the Bering Sea and Aleutian Islands (BSAI).
- Managed under the Fishery Management Plans for Groundfish of the Gulf of Alaska and Bering Sea/Aleutian Islands:
- Thornyheads are managed as a “bycatch only” fishery in the GOA because they are nearly always taken in fisheries directed at sablefish and other rockfish.
- Directed fishing on thornyhead exclusively is not permitted.//
Harvest
- Commercial fishery:
- In 2020, commercial landings of shortspine thornyhead totaled 930,000 pounds and were valued at more than $1.5 million, according to the NOAA Fisheries commercial fishing landings database.
- Gear types, habitat impacts, and bycatch:
- The trawl, longline, and pot gear used to harvest shortspine thornyhead have minimal or temporary effects on habitat. Area closures and gear restrictions protect sensitive rocky, cold-water coral and sponge habitats from bottom trawl gear.
- In the Gulf of Alaska, they are mainly caught with trawl and longline gear as bycatch in the rockfish and sablefish fisheries. On the Pacific Coast, they are targeted in the rockfish fishery with bottom trawl, longline, and pot gear.
- Recreational fishery:
- Thornyheads are occasionally caught in recreational fisheries but are not often targeted, due to the complications of deep-sea fishing.
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