English Sole (Parophrys vetulus)

• English sole population levels are high and no overfishing is occurring.
• Federal management measures to limit the number of vessels in the Pacific fishery for English sole have been successful in keeping the stock healthy.
• English sole are an excellent source of low-fat protein, selenium, and vitamins. For more on nutrition, see Nutrition Facts. (USDA)
• Most English sole sold in U.S. markets comes from the domestic fishery with a small amount imported from Canada.

Sustainability Status

Biomass: Pacific coast English sole spawning biomass was estimated to be 41,907 metric tons in 2007, 2.9 times the target biomass.
Overfishing: No
Overfished: No
Fishing and habitat: Bottom trawls are used to catch English sole on soft bottoms off the Pacific coast. Because the species inhabiting soft bottom communities are frequently fast growing and short-lived, these communities may be more resilient to trawling impacts than other habitats. The Alaska Fisheries Science Center's Auke Bay Laboratory and Resource Assessment and Conservation Engineering Division are currently conducting studies on the effects of bottom trawling on habitat.
Bycatch: Modified flatfish-targeting trawl gear has been designed to reduce the incidental catch of rockfish and other species.
Aquaculture: There is currently no aquaculture production of English sole, although flatfish in general are being researched for their aquaculture potential.

Science and Management

English sole has been an important commercial fish, primarily harvested off the coasts of Washington, Oregon, and northern and central California. The fishery is managed by the Pacific Fishery Management Council through the Pacific Coast Groundfish Fishery Management Plan. All sectors of the groundfish fishery are currently constrained by the need to rebuild the groundfish species that have been declared overfished. Groundfish are managed through a number of measures, including harvest guidelines, quotas, trip and landing limits, area restrictions, seasonal closures, and gear restrictions (such as minimum mesh size for nets). Amendment 6 set up a limited entry program for the groundfish fishery in 1994. English sole, specifically, are managed under coast-wide Acceptable Biological Catches (ABCs); however, landing restrictions (on size and amount) imposed by processors have also affected retention/discarding patterns in recent decades. In 2003, NOAA's National Marine Fisheries Service (NMFS) implemented a vessel buyback program to reduce the number of vessels and permits in the Pacific coast groundfish trawl fishery in order to increase productivity, financially stabilize the fishery, and conserve and manage fish. Off the Pacific coast, the Northwest Fisheries Science Center - Fishery Resource Analysis and Monitoring Division (FRAM) conducts annual bottom trawl surveys that collect data on English sole biomass and size composition.

There is a small U.S. fishery for English sole in the Gulf of Alaska that is managed under the Gulf of Alaska Groundfish Fishery Management Plan; however, the majority of domestic landings are from the West Coast fishery.

An intern at NOAA's Alaska Fisheries Science Center (AFSC) recently conducted a study on the preferred habitat of English sole. Juvenile English sole consistently demonstrated a preference for structured habitat rather than bare sand. These findings provide evidence for the importance of emergent structure as a part of essential fish habitat for juvenile English sole and are being followed with field investigations. Another AFSC intern recently researched how English sole responded to fishing gear under various conditions. This type of study will aid in the design of fishing strategies and gears that reduce bycatch.

Scientists from NOAA's Northwest Fisheries Science Center sought to understand which nearshore areas in Puget Sound contribute juveniles to adult populations. Using environmental markers found in the ear bones (otoliths) of adult English sole, they identified several regions (e.g., non-developed and developed nearshore areas in northern and southern Puget Sound) which the majority of these fish occupied when they were juveniles. Knowledge of the whereabouts of these juvenile habitats represents a critical first step in helping to ensure the maintenance and sustainability of their population, especially with growing human encroachment.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed.

• Geographic range: Off the Pacific coast of the United States, Mexico, and Canada from Nunivak Island, Bering Sea and Agattu Island, Aleutian Islands to Bahia San Cristobal, central Baja California.
• Habitat: Juvenile English sole inhabit estuaries and nearshore areas, including the Puget Sound and Strait of Georgia, and adults range to depths of over 1,800 feet. Adults and juveniles prefer soft bottoms composed of fine sands and mud but have also been found in eelgrass habitats. English sole use nearshore and estuarine waters as nursery areas.
• Life span: Males can live to at least 16 years, and females can live to at least 20 years.
• Food: Larvae are planktivorous, eating tiny drifting plants and animals. Juveniles and adults are carnivorous, eating copepods (small crustaceans), amphipods (shrimp-like crustaceans), cumaceans (also known as lollipop shrimp), mysids (shrimp-like crustaceans), polychaete worms, small bivalves, clam siphons, and other bottom-dwelling invertebrates. English sole feed by day using sight and smell and sometimes dig for prey.
• Growth rate: Females grow to twice as long as males.
• Maximum size: English sole are relatively small-bodied for a commercial species; maximum sizes are less than 2 feet.
• Reaches reproductive maturity: Some females mature as 3-year-olds; all females over 1.15 feet long are mature. Males mature at 2 years (8 inches).
• Reproduction: A foot-long female can produce 150,000 eggs, and a 1.4-foot female can produce 2 million eggs. Eggs are slightly buoyant but sink before hatching a few days after spawning. Larvae remain in the surface waters for about 2 to 3 months. Juveniles spend 1-2 years rearing in coastal estuaries or the nearshore zone of the open coast before moving to deeper waters.
• Spawning season: From winter to early spring, depending on geographic area.
• Spawning grounds: Over soft-bottom mud substrate at depths of 164 to 230 feet.
• Migrations: Most adults make limited migrations, but a few individuals move much longer distances. English sole may migrate north after spawning in the spring on their way to summer feeding grounds and return south in the fall.
• Predators: Predators of juveniles include fish-eating birds (such as great blue heron), larger fishes, and marine mammals. Adults may be eaten by marine mammals, sharks, and other large fishes.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: English sole are a common right-eyed flatfish species. They have a pointed-snout and their upper eye is visible from their non-eyed side.

Role in the Ecosystem

The English sole is very susceptible to changes in its environment. Because the English sole relies on estuaries for nursery habitat, the species is impacted by pollution and habitat alteration. Bay waters and sediments collect runoff and are often the dumping grounds for industrial and municipal wastes. In Puget Sound, for example, the many toxins English sole is exposed to accumulate in its tissue, resulting in high levels of contaminants which can cause disease, tumors, and reduced reproductive success.

Additional Information

Market name: Sole
Vernacular name: Lemon sole
Several other species are marketed as Sole.

Biomass

Biomass refers to the amount of English sole in the ocean. Scientists cannot collect and weigh every single fish to determine biomass, so they use models to estimate it instead. These biomass estimates can help determine if a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes in the regulations of the fishery.

Off the West Coast, English sole biomass has been increasing rapidly over the past decade after large recruitment events from 1998-2002. This follows a period of poor recruitments from the mid-1970s to the mid-1990s, which left the stock at nearly historically low levels.

Landings

Landings refer to the amount of catch that is brought to land. Overall landings off the West Coast have declined since the mid-1960s and are at nearly historical lows in recent years. This is mainly due to market factors and management restrictions for other groundfish species.

Note: Only domestic commercial landings are presented in the graph.

Biomass and Landings

Are landings and biomass related? Landings are dependent on biomass, management measures in the fishery, and fishing effort.

Data sources:
Biomass and landings from the Updated U.S. English sole stock assessment: Status of the resource in 2007

Important Dates

1876 – Earliest record of trawl fishing off California
1982 – Pacific Fishery Management Council's Pacific Coast Groundfish Fishery Management Plan implemented
1993 – Pacific coast English sole spawning biomass found to be increasing, and the fishery is sustainable
1994 – Amendment 6 to the Pacific Coast Groundfish FMP sets up a limited entry program for the groundfish fishery
1999 – Strong year class for many groundfish off west coast, possibly the largest in the English sole time-series.
2002 – Rockfish conservation area (RCA) closed to protect overfished species
2003 – NOAA's National Marine Fisheries Service (NMFS) implements a vessel buyback program.
2005 – Selective flatfish trawl gear required in shallow waters. English sole assessment finds stock to be at high biomass levels.

Notes and Links

General Information:
Pacific Fishery Management Council Primer on Groundfish

NMFS Northwest Regional Office Groundfish Fishery Management page

Fishery Management:
Pacific Coast Groundfish Fishery Management Plan

Stock Assessments:
Updated U.S. English sole stock assessment: Status of the resource in 2007

Status of the U.S. English sole resource in 2005