Dover Sole

About The Species

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

Status

• On the West Coast, Dover sole were last assessed in 2011.
  • According to the 2011 stock assessment, Dover sole are not overfished on the West Coast, and are not subject to overfishing based on 2016 catch data.
• In the Gulf of Alaska, Dover sole are assessed as part of a complex with other flatfish, called the “deepwater flatfish complex”:
  • According to the 2018 stock assessment, this complex is not overfished and not subject to overfishing.
• In the Bering Sea/Aleutian Islands, Dover sole are assessed as part of a complex with other flatfish, called the “other flatfish complex”:
  • This complex was last assessed in 2018, but data were insufficient to determine whether the complex is overfished.
  • An overfishing level is set for the complex, and as long as this level is not exceeded the complex is not subject to overfishing. The complex is not subject to overfishing.

Appearance

• Dover sole are flatfish, with both of their eyes located on the right side of their head.

• Their mouths are small relative to their size.

• Their drab coloring helps them camouflage themselves on the ocean floor.

• In some areas, Dover sole are referred to as “slippery sole” because they excrete mucous onto their skin/scales, making them incredibly slippery and hard to pick up.  

Biology

• Females grow faster and larger than males, up to 30 inches long, about 2 to 4 inches longer than males.
• Males can live up to 58 years, about 5 years longer than females.
• Dover sole spawn near the ocean floor in waters deeper than 1,440 feet. Spawning seasons vary by location:
  • In the Gulf of Alaska from January to August.
  • Off Oregon from November to April.
  • In Puget Sound from January to March.
• Females produce between 52,000 to 266,000 eggs, which can be as large as 0.1 inches.
• Dover sole eggs are fertilized externally and are found in the upper part of the water column.
• Once hatched, larvae settle into deeper water, then travel inshore to find suitable nursery areas.
• Dover sole larvae usually settle to the bottom after a year of living in the upper water column, but some remain larvae for as long as 2 years.
  • Scientists believe these “holdover” larvae delay settling to the bottom due to unfavorable environmental conditions.

• Dover sole feed during the daytime by sight and smell.
• Their mouths are well adapted for feeding on small invertebrates that live within ocean floor sediments.
• Larval Dover sole feed on small crustaceans, eggs, and larval crustaceans as well as plankton.
• Juveniles and adults feed on worms, bivalves, brittle stars, and small bottom-dwelling crustaceans.
• Seabirds and fish that live near the surface prey on larval Dover sole.
• Sharks, bottom-feeding marine mammals, Pacific cod, arrowtooth flounder, and sometimes sablefish feed on juveniles and adults.

Where They Live

• Dover sole is found in the Pacific Ocean from the Bering Sea and western Aleutian Islands to southern Baja California.

Management

• NOAA Fisheries and the Pacific Fishery Management Council manage the Dover sole fishery on the West Coast.
• Managed under the Pacific Coast Groundfish Fishery Management Plan:
  • Limits on the number of permits and fishermen allowed.
  • Limits on the minimum size of fish that may be harvested.
  • 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 includes:
    • Catch limits based on the health of each fish stock and divided into shares that are allocated to individual fishermen or groups.
    • These fishermen can decide how and when to catch their share – preferably when weather, markets, and business conditions are most favorable, allowing the fishery the flexibility to be more environmentally responsible, safer, more efficient, and more valuable.
• NOAA Fisheries and the North Pacific Fishery Management Council manage the Dover sole fishery in Alaska.
• Managed under the Gulf of Alaska Groundfish Fishery Management Plan:
  • Total allowable catch is allocated by regulatory area (western, central, and 2 sub-areas of the eastern Gulf of Alaska).
• Managed under the Bering Sea/Aleutian Islands Groundfish Fishery Management Plan:
  • Dover sole is managed as part of the other flatfish complex.
• In the Gulf of Alaska and Bering Sea:
  • Fishermen must have a permit to participate in these fisheries, and the number of available permits is limited to control the amount of fishing.
  • Managers set limits on how much Dover sole can be caught. Catch is monitored through record keeping, reporting requirements, and observer monitoring.