Rock Sole
Rock Sole
Lepidopsetta billineta (southern rock sole) and Lepidopsetta polyxystra (northern rock sole)
Also Known As
Sole, Flounder, Rock flounder, Two-lined flounder, White-bellied flounder
Quick Facts
Region
Alaska,
West Coast
Rock sole. Credit: NOAA Fisheries
Rock sole. Credit: NOAA Fisheries
About the Species
U.S. wild-caught rock sole is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.
Population
The stocks in Alaska are not overfished.
Fishing Rate
Not subject to overfishing.
Habitat Impact
Area closures and gear restrictions protect habitat affected by bottom trawls used to harvest rock sole.
Bycatch
Regulations are in place to minimize bycatch.
Population Status
- There are two species of rock sole: Northern rock sole and rock sole. Both Northern rock sole and rock sole are contained in the Bering Sea/Aleutian Islands Rock Sole Complex and the Gulf of Alaska Shallow Water Flatfish Complex. Rock sole is contained in the Other Flatfish Complex along the Pacific coast. According to the most recent stock assessments:
- Northern rock sole and rock sole are managed as part of the Bering Sea/Aleutian Islands Rock Sole Complex, where Northern rock sole is the primary species in the complex and has been assessed. The complex is not overfished based on the assessment of Northern rock sole (2022 stock assessment) and not subject to overfishing based on 2022 catch data. Summary stock assessment information can be found on Stock SMART.
- Northern rock sole and rock sole are managed as part of the Gulf of Alaska Shallow Water Flatfish Complex, and both stocks are primary species in the complex and have been assessed. The complex is not overfished based on the assessments of Northern rock sole (2017 stock assessment) and rock sole (2017 stock assessment), and not subject to overfishing based on 2022 catch data. Summary stock assessment information for Northern rock sole can be found on Stock SMART and for rock sole on Stock SMART.
- Rock sole is managed as part of the Other Flatfish Complex and has not been assessed so the population status is unknown. This complex is not subject to overfishing based on 2021 catch data.
Appearance
- Rock sole are a flatfish with both eyes located on the right side of their head.
- Northern rock sole’s underside is creamy white, whereas southern rock sole’s underside is white with glossy highlights.
- Rock sole are sometimes called roughback because of the rough scales on their backs.
Biology
- Rock sole grow up to 2 feet long and can live for more than 20 years.
- They are able to reproduce when they reach 4 to 7 years old.
- Northern rock sole spawn in midwinter and spring, and southern rock sole spawn in the summer.
- Females lay eggs near the ocean bottom, and the eggs stick wherever they land. Eggs hatch between 6 and 25 days later, depending on water temperature.
- Larval rock sole eat plankton and algae.
- Early juveniles eat zooplankton, and late juvenile and adults prey on bivalves, worms, amphipods, mollusks, and crustaceans.
- Larger fishes, including rock sole, feed on larval and juvenile rock sole.
- Sharks, marine mammals, and larger fishes prey on adults.
- Rock sole’s coloring and movements on the sea floor often confuse predators.
Where They Live
Range
- Northern rock sole are found from Puget Sound through the Bering Sea and Aleutian Islands to the Kuril Islands (north of Japan).
- Southern rock sole are found from the southeast Bering Sea to Baja California.
Habitat
- Larvae are found in the upper 100 feet of the water column. Juveniles move to deeper water as they grow larger.
- Juveniles and adults live on the ocean bottom and are found in shallow-water bays over the continental shelf.
- They can be found as deep as 2,400 feet but are uncommon below 985 feet.
- Rock sole prefer sandy or gravel ocean bottoms.
Fishery Management
- NOAA Fisheries and the North Pacific Fishery Management Council manage this fishery in Alaska.
- Managed under the Fishery Management Plans for Groundfish of the Bering Sea and Aleutian Islands and Gulf of Alaska:
- Fishermen must have a permit to participate in the fishery, and the number of available permits is limited to control the amount of fishing.
- Managers set an annual catch limit for rock sole.
- In the Bering Sea/Aleutian Islands a percentage of the annual catch limit is allocated to the community development quota program, which benefits fishery-dependent communities in Western Alaska. The rest is allocated under a catch share program to a trawl catcher/processor sector based on historic harvest and future harvest needs to improve retention and utilization of fishery resources by the trawl fleet.
- In the Gulf of Alaska, total allowable catch is allocated by regulatory area (western, central, and two sub-areas of the eastern Gulf of Alaska).
- Catch is monitored through record keeping, reporting requirements, and observer monitoring.
- NOAA Fisheries and the Pacific Fishery Management Council manage this fishery on the West Coast.
- Managed under the Pacific Coast Groundfish Fishery Management Plan:
- Only a small amount of rock sole is harvested incidentally in fisheries off the West Coast.
- Rock sole is included in the groundfish fishery management plan, but it is not assessed or directly managed.
Harvest
- In 2022, commercial landings of rock sole totaled $40.3 million pounds and were valued at $7.7 million, according to the NOAA Fisheries commercial fishing landings database.
- Almost all commercial harvest of rock sole comes from Alaska, mainly the Bering Sea.
- Gear types, habitat impacts, and bycatch:
- Bottom trawls are primarily used to harvest rock sole.
- Trawls can contact the ocean floor and impact habitats, depending on the characteristics of the ocean bottom and the size of the gear.
- Bering Sea/Aleutian Islands and Gulf of Alaska fishermen use a modified trawl gear which reduces the impact of trawling on animals living on the sea floor, including crabs.
- Halibut, salmon, and crab are sometimes incidentally caught in the groundfish fishery in Alaska.
- There is a limit on how much halibut, herring, and crab can be incidentally caught. If this limit is reached, an area or the entire fishery is closed for the remainder of the season.
- NOAA Fisheries and the regional fishery management council have implemented large closed areas to protect sensitive rocky, cold-water coral and sponge habitats from bottom trawls.
Scientific Classification
- Northern rock sole are found from Puget Sound through the Bering Sea and Aleutian Islands to the Kuril Islands (north of Japan).
- Southern rock sole are found from the southeast Bering Sea to Baja California.
- Larvae are found in the upper 100 feet of the water column. Juveniles move to deeper water as they grow larger.
- Juveniles and adults live on the ocean bottom and are found in shallow-water bays over the continental shelf.
- They can be found as deep as 2,400 feet but are uncommon below 985 feet.
- Rock sole prefer sandy or gravel ocean bottoms.
Fishery Management
- NOAA Fisheries and the North Pacific Fishery Management Council manage this fishery in Alaska.
- Managed under the Fishery Management Plans for Groundfish of the Bering Sea and Aleutian Islands and Gulf of Alaska:
- Fishermen must have a permit to participate in the fishery, and the number of available permits is limited to control the amount of fishing.
- Managers set an annual catch limit for rock sole.
- In the Bering Sea/Aleutian Islands a percentage of the annual catch limit is allocated to the community development quota program, which benefits fishery-dependent communities in Western Alaska. The rest is allocated under a catch share program to a trawl catcher/processor sector based on historic harvest and future harvest needs to improve retention and utilization of fishery resources by the trawl fleet.
- In the Gulf of Alaska, total allowable catch is allocated by regulatory area (western, central, and two sub-areas of the eastern Gulf of Alaska).
- Catch is monitored through record keeping, reporting requirements, and observer monitoring.
- NOAA Fisheries and the Pacific Fishery Management Council manage this fishery on the West Coast.
- Managed under the Pacific Coast Groundfish Fishery Management Plan:
- Only a small amount of rock sole is harvested incidentally in fisheries off the West Coast.
- Rock sole is included in the groundfish fishery management plan, but it is not assessed or directly managed.
Harvest
- In 2022, commercial landings of rock sole totaled $40.3 million pounds and were valued at $7.7 million, according to the NOAA Fisheries commercial fishing landings database.
- Almost all commercial harvest of rock sole comes from Alaska, mainly the Bering Sea.
- Gear types, habitat impacts, and bycatch:
- Bottom trawls are primarily used to harvest rock sole.
- Trawls can contact the ocean floor and impact habitats, depending on the characteristics of the ocean bottom and the size of the gear.
- Bering Sea/Aleutian Islands and Gulf of Alaska fishermen use a modified trawl gear which reduces the impact of trawling on animals living on the sea floor, including crabs.
- Halibut, salmon, and crab are sometimes incidentally caught in the groundfish fishery in Alaska.
- There is a limit on how much halibut, herring, and crab can be incidentally caught. If this limit is reached, an area or the entire fishery is closed for the remainder of the season.
- NOAA Fisheries and the regional fishery management council have implemented large closed areas to protect sensitive rocky, cold-water coral and sponge habitats from bottom trawls.
Scientific Classification
| Kingdom | Animalia | Phylum | Chordata | Class | Actinopterygii | Order | Pleuronectiformes | Family | Pleuronectidae | Genus | Lepidopsetta | Species | bilineata |
|---|
Featured News
Alaska pollock. Credit: NOAA Fisheries.
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Seafood Facts
Is Rock Sole Sustainable?
U.S. wild-caught rock sole is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.
Availability
Year-round.
Source
U.S. wild-caught from Alaska to California (but mainly Alaska).
Taste
Mild, sweet flavor.
Texture
Small, tender flakes.
Color
Creamy white flesh.
Health Benefits
Rock sole is an excellent source of low-fat protein, calcium, and other nutrients.
Nutrition Facts
Servings: 1; Serving Weight: 100 g; Calories: 91; Protein: 18.84 g; Total Fat: 1.19 g; Total Saturated Fatty Acids: 0.283 g; Carbohydrate: 0 g; Total Sugars: 0 g; Total Dietary Fiber: 0 g; Cholesterol: 48 mg; Selenium: 32.7 mcg; Sodium: 81 mgSeafood News
A chef prepares various finger foods made from squid fins in the Dr. Matthew Highlands Food Pilot Plant in Hitchner Hall at the University of Maine. Several chefs were invited to create dishes as part of a research project to develop new frozen foods made from squid fins. Photo courtesy of the University of Maine.
Seafood on ice for display. Credit: Shutterstock
Mussel longline aquaculture. Credit: Darryl Torckler
Science Overview
Image
NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of rock sole. The results of this research are used to inform management decisions for this species.
For detailed information about stock status, management, assessments, and resource trends, you can search for rock sole, and any other species of interest, using NOAA’s StockSMART web tool.
Rock Sole Research in Alaska
Rock sole, along with other flatfishes, are an important trawl fishery resource in the Bering Sea and Gulf of Alaska. Scientists at NOAA’s Alaska Fisheries Science Center research the distribution and abundance, growth and maturity, habitat preference, migration behavior, and food relationships of rock sole. Their work provides crucial information for understanding and managing this species.
