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Longspine thornyhead are considered an affordable seafood option and are available year-round. They do not have swim bladders, and thus unlike most other rockfish species and other deep-sea fishes, do not suffer barotrauma when fished from the depths. They can be sold alive or released after capture with a much higher survival rate. They are also sold whole, headed and gutted, in fillets, and in value-added form. Fillets hold together better with the skin-on, but in general longspine thornyhead hold well in many preparations, including dressed whole on a barbecue. Their texture falls between delicate flounder and firm swordfish and has a delicate, nutty flavor. Rockfish are generally either red-fleshed and brown-fleshed, of which longspine thornyhead falls into the red-fleshed category. Red-fleshed fillets are more desirable because they are leaner, less oily, and have a longer shelf life. Brown-fleshed rockfish have a stronger flavor.
- Frozen Block
Health & Nutrition
- Total Fat1.60g
Longspine thornyhead are also known as “idiot fish” because of their oversized heads and eyes. They get their name “thornyhead” from their characteristic thorny spine across their cheek. They have 15 dorsal spines, with the third one especially elongated. They appear similar to shortspine thornyhead underwater, but their gill chamber is black rather than light like the shortspine thornyhead. When viewed underwater, adults have orange or orange-red bodies with large white patches and some dark stippling. Once caught, they look red with black on their fins. Longspine thornyhead grow up to 15 inches (39 centimeters) in length and can live up to 45 years. Females typically mature by 23 years.
Longspine thornyhead are oviparous and lay gelatinous masses of eggs that float to the surface during spawning season, which lasts from January to May. These floating egg masses can be seen at the surface from March through May. Females spawn 2-4 times per year and release between 20,000 and 450,000 eggs during the spawning months. The hatched larvae stay within 656 feet (200 meters) of the surface for up to six months, and juveniles settle into deeper habitats within a year after. Mixing of larger populations, namely the shortspine thornyhead, and smaller populations is known to lead to cannibalism within the community. Deep-water thornyhead have adapted to deeper, food-deprived environments by adopting a sedentary adult phase. Their bodies do not contain a swim bladder, allowing them to better withstand the high pressure near the ocean floor, as well as make it easier to move within the water column; however, their exact survival rate on temporary exposure to low pressure upon catch and release is unknown.
These fish are ambush predators, consuming fish fragments, crustaceans, bivalves, and polychaetes. Juveniles eat a variety of small crustaceans and herbivorous euphausiids, and adults feed mostly on brittle stars, grooved tanner crabs, myctophids, and smaller thornyhead. Both juveniles and adults are prey to shortspine thornyhead and other piscivorous fish like sablefish.
Longspine thornyhead are found along the Pacific coast of North America ranging from Cabo San Lucas in southern Baja California, Mexico to the western Gulf of Alaska and Aleutian Islands. In the western Pacific, longspine thornyhead range from Russia to as far south as northern Japan. They can inhabit relatively deep water, in depths from 663 to 5,795 feet (201 to 1,756 meters) but are most common between 1,815 to 4,290 feet (500 to 1,300 meters). Eggs are pelagic and juveniles occur in midwater – eventually settling on the seafloor as adults.
Longspine thornyhead prefer soft sand and mud bottoms in deep water environments synonymous with low productivity, high pressure, and reduced oxygen concentrations. To cope with living in such environments, adults are generally found resting on the seafloor in small depressions or near small rocks and sponges, remaining motionless for long periods of time. Due to their slow metabolisms and sedentary nature, they can wait an average of 130 to 180 days between feedings. Longspine thornyhead are better adapted to deep water than shortspine thornyhead, likely due to a more adapted enzymatic system. They are thought to play a significant ecological role in benthic environments, especially in Canadian waters along the continental slope where they are the dominant fish species. Adults do not school or aggregate.
Longspine thornyhead population is assessed using data from the fishery and from scientific trawl surveys. More effort is needed to reconstruct historical catches for better accuracy in stock assessments and analysis. Aging method validation is needed, as well as age and growth information for future stock assessments. Research on the stock and its range in deeper waters is necessary and can be done by conducting a survey using towed cameras. An investigation of the possible discontinuity in the reconstructed thornyhead historical catches would also be useful for future assessments.
A DNA study in 2000 suggests genetic mixing of longspine thornyhead along the United States Pacific coast. It is unknown if separate stocks exist along their range. There is no genetic information about the longspine thornyhead population in Canada’s Pacific.Management:
The commercial fishery for longspine thornyhead along the US Pacific coast has grown over the last several decades due to the development of Northern American export to Japan where they are considered a delicacy (19% of US exports go to Japan). Recreational fisheries rarely catch longspine thornyhead, and recreational harvest within Puget Sound is closed.
NOAA Fisheries and the Pacific Fishery Management Council (PFMC) manage the longspine thornyhead fishery in California, Oregon, and Washington under the Pacific Coast Groundfish Fishery Management Plan (FMP). Implemented in 1982, the Pacific Coast Groundfish FMP covers over 90 species including rockfish, skates, and other flatfish caught off the US West Coast. Longspine thornyhead were first regulated in 1990. The US commercial groundfish fishery is comprised of three components: Limited Entry (LE), Open Access (OA), and Nearshore (NS). The LE and OA sectors are managed by the PFMC while the NS sector is jointly managed by the PFMC and the states of Oregon and California.
In the Gulf of Alaska and Bering Sea/Aleutian Islands, longspine thornyhead are managed under the FMP for groundfish, where they are managed as a bycatch-only fishery as they are nearly always taken in fisheries directed at sablefish and other rockfish species. Exclusive targeted fishing on longspine thornyhead is prohibited.
Catch history of longspine thornyhead was previously difficult to resolve due to possible confusion of landed catch with shortspine thornyhead. However, populations along the US West Coast are considered healthy and landings have been below the established catch limits since 1999. The fishery is considered well-managed due to measures such as:
- A limited entry program – limiting the number of commercial fishing permits available
- Minimum size and total catch limits
- Seasonal and closed areas to protect sensitive habitats
- A vessel monitoring system to ensure vessels are complying with closed areas
- Gear restrictions
Beginning in 2011, LE trawl permit holders were allowed to participate in a catch share program. Participants in the program received an Individual Fishing Quota (IFQ) of the total catch of the 29 commercial species/species complexes along the US West Coast. Fishers participating in the program can fish their quota anytime during the season and can use non-trawl gear to catch their quota shares. Whereas non-IFQ fisheries have varying levels of at-sea observer coverage, the catch share program requires 100 percent at-sea and dockside monitoring. A subset of the IFQ, the California Groundfish Collective, comprises 11 fishing operations that have entered into an agreement to pool members’ IFQs. The US West Coast limited entry groundfish trawl fishery was MSC-certified in June 2014.
Longspine thornyhead are managed by the Department of Fisheries and Oceans Canada (DFO) under the Integrated Fishery Management Plan (IFMP) for Groundfish in Canada. In 1996 a directed fishery for longspine thornyhead was developed in Canadian waters prior to which the species was not targeted commercially. Under the 2016 IFMP, the trawl fishery is allocated 95.35% of the total allowable catch (TAC) with the hook and line rockfish and halibut and trawl sectors being allocated 2.29% and 2.36% of the TAC, respectively. Recent management changes to the trawl fishery reduced its access to deep-water habitats, which contain longspine thornyhead. Among management measures the DFO establishes under the IFMP for Groundfish include:
- An Individual Vessel Quota (IVQ) system in which IVQs can be reallocated between vessels and fisheries as necessary
- 100 percent at-sea and dockside monitoring
- Gear restrictions
- Habitat conservation measures such as spatial closures to avoid bycatch of sensitive corals and sponges
Impact on Stock
Although longspine thornyhead are inherently vulnerable to fishing pressure due to their slow growth, their abundance and fishing mortality are rated as very low concern. US West Coast populations of longspine thornyhead declined somewhat from the 1970s through the end of the 1990s, but spawning biomass has steadily increased since then. Abundance in sablefish, its main predator, reduced in the late 1970s, which also allowed its biomass to remain relatively constant even with increasing fishing mortality. Fishing mortality has consistently been below the 50% target since 1997 and stocks are currently considered healthy. The most recent stock assessment was completed in 2013.
In Canada, historically since the beginning of the targeted commercial fishery in 1996, there was a substantial decline in the commercial catch per unit effort of over 50% for at least 8 years. Currently, there is no stock assessment for longspine thornyhead and thus the stock status is unknown. Combined with their inherent vulnerability, this is of high concern. However, overfishing is of low concern as recent catches have been low relative to prior years.
There are no serious concerns about seafloor impacts in both US and Canadian groundfish fisheries. Longspine thornyhead fisheries include both longline and trawl gears, which have minimal or temporary habitat effects in these fisheries. The combination of spatial restrictions and gear modifications help reduce habitat impacts.
Bycatch along the US West Coast is closely managed, and mandatory use of selective flatfish trawl nets helps reduce bycatch. Groundfish fisheries can catch other species that are depleted, vulnerable to overfishing or both, but are not being overfished. However, bycatch for US longspine thornyhead using bottom trawl on soft substrates includes sablefish, longnose skate, dover sole, shortspine thornyhead, and splitnose rockfish.
There are serious bycatch concerns in the Canadian groundfish fishery as other species that are depleted, vulnerable to overfishing or both, are caught. Some of these higher risk bycatch species include longnose skate, Pacific grenadier, school shark, giant rattail, green sturgeon, and shortspine thornyhead.
Longspine thornyhead management on the US West Coast is considered strong and management measures include: 100% observer coverage on trawlers, gear restrictions and a catch share program.
In Canada, there is a moderately effective management framework in place, but implementation is inconsistent and many species in the fishery, including longspine thornyhead, have not been assessed. Further policies are being developed to protect the ecosystem.
|Central California Seafood Marketing Association||United States||California|
|Fort Bragg Groundfish Association||United States||California|
|Pacific Seafood Group, Inc.||United States||Oregon|
|Real Good Fish||United States||California|
|Royal Hawaiian Seafood||United States||California|
|Sea to Table, USA||United States||New York|
|South Bay Wild, Inc.||United States||California|
|Tradex Foods Inc.||Canada||British Columbia|
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