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Rock Sole

Lepidopsetta billineta (southern rock sole) and Lepidopsetta polyxystra (northern rock sole)

Rock sole

Also Known As

  • Sole
  • Flounder
  • Rock flounder
  • Two-lined flounder
  • White-bellied flounder

U.S. wild-caught rock sole is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.

Population

Above target population levels.

Fishing Rate

At recommended levels.

Habitat Impacts

Area closures and gear restrictions protect habitat affected by bottom trawls used to harvest rock sole.

Bycatch

Regulations are in place to minimize bycatch.

  • 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.

The U.S. Fishery

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 2016, commercial landings of rock sole totaled approximately 102 million pounds and were valued at more than $14.8 million.
    • 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.

The Science

Population Status

  • There are two species of rock sole, northern rock sole and southern rock sole.
  • Northern rock sole are found in the Bering Sea/Aleutian Islands, and according to a 2017 assessment are not overfished and are not subject to overfishing.
  • Both the northern and southern species of rock sole are found in the Gulf of Alaska, and according to a 2017 assessment are not overfished and are not subject to overfishing.
  • On the West Coast, rock sole make up only a small percentage of groundfish harvests. Scientists do not formally assess this species so the population status is unknown.
  • Rock sole are part of the “other flatfish” complex on the West Coast, and are not subject to overfishing based on 2016 catch data.

Location

  • 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. 

Physical Description

  • 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. 

Last updated: 09/20/2018