Rex Sole
Glyptocephalus zachirus
Also known as Witch sole, Threadfin sole
Culinary Profile
Mild and sweet.
Tender with fine, firm flakes.
Rex sole is an excellent source of low-fat protein.
Gastronomic Specifications
Biology & Habitat
Appearance
Rex sole is a flatfish with both eyes located on the right side of its head. They have small mouths with a blunt, rounded snout. Their body is oval, but elongated, and very slender. The upper side of their body is light brown to gray in color and their underside is white.
Biology
Rex sole are moderately long-lived (they can live for nearly 30 years), and can grow up to 23 inches. Female rex sole grow faster and live longer than males. Depending on location, rex sole may reach maturity between 3.5 and 13 years. Rex sole spawn from October through May. They are serial spawners, and will deposit eggs on more than one occasion throughout the spawning season.
Where They Live
Range Rex sole are found from central Baja California to the Bering Sea. Habitat Rex sole live on sandy or muddy ocean bottoms. They are found at depths between 100 and 200 meters and are found throughout the Gulf of Alaska. Along the coast of the Pacific Northwest they are found at depths of about 500 meters.
How to Buy & Source
Availability
Year-round, but highest catch is from February through May.
Source
U.S. wild-caught from Alaska to California (but mainly from Alaska).
Commercial Fishery & Harvest
In 2023, landings of rex sole totaled 4.7 million pounds and were valued at $1.3 million, according to the NOAA Fisheries commercial fishing landings database . Gear types, habitat impacts, and bycatch: Bottom trawls are used to catch rex sole. Trawls that are used to harvest rex sole can contact the ocean floor and impact habitats, depending on the characteristics of the ocean bottom and the size of the gear. Bottom trawls cause minimal damage to habitat when targeting rex sole over soft, sandy, or muddy ocean bottoms on the West Coast and in Alaska. In Alaska and on the West Coast, NOAA Fisheries and the regional fishery management councils have implemented large closed areas to protect sensitive rocky, cold-water coral and sponge habitats from bottom trawls.
Nutritional Benchmarking Across 65 Species
Where Rex Sole ranks against the rest of the catalogue on each of USDA FoodData Central's per-100 g nutrient measures.
| Nutrient | Value | Rank | Percentile |
|---|---|---|---|
| Choline | 65 mg | 12 / 65 | 82% |
| Phosphorus | 252 mg | 16 / 111 | 86% |
| Vitamin D | 2.8 IU | 25 / 54 | 54% |
| Omega-3 EPA | 137 mg | 47 / 104 | 55% |
| Omega-3 DHA | 108 mg | 76 / 104 | 27% |
| Vitamin B12 | 1.13 µg | 80 / 106 | 25% |
| Selenium | 26.6 µg | 95 / 106 | 10% |
| Iron | 0.18 mg | 98 / 111 | 12% |
| Protein | 12.41 g | 100 / 111 | 10% |
| Zinc | 0.32 mg | 102 / 111 | 8% |
Other Alaska Fisheries
Sustainable species managed out of the same regional fishery council as Rex Sole.
Arrowtooth Flounder
Atheresthes stomias
Mild, sweet flavor.
Bocaccio
Sebastes paucispinis
Delicate, nutty, sweet flavor.
Canary Rockfish
Sebastes pinniger
Delicate, nutty, sweet flavor.
Chinook Salmon
Oncorhynchus tshawytscha
Chinook salmon has a pronounced buttery, rich taste. They are the most highly prized salmon in the culinary world.
Chum Salmon
Oncorhynchus keta
Chum salmon has a lower oil content than other wild salmon, so it has a relatively mild flavor.
Coho Salmon
Oncorhynchus kisutch
Smaller coho have a delicate flavor. Fillets from larger fish have a mild taste.
Dover Sole
Microstomus pacificus
Mild and sweet.
English Sole
Parophrys vetulus
Mild taste with a slight shellfish flavor.
Flathead Sole
Hippoglossoides elassodon
Mild and delicate flavor.
Geoduck
Panopea generosa
The neck is tough and crunchy, while the belly meat is tender and sweet.
Similar by Flavour: Other Mild-Tasting Species
If you enjoy the mild flavour profile of Rex Sole, these other species in the catalogue will feel familiar on the palate.
Acadian Redfish
Sebastes fasciatus
Mild and slightly sweet. Redfish can be used as a substitute for haddock and similar fish.
Alaska Pollock
Gadus chalcogrammus
Pollock has mild-tasting flesh and is similar to other white fish like cod or haddock.
American Lobster
Homarus americanus
Mild and sweet.
Arrowtooth Flounder
Atheresthes stomias
Mild, sweet flavor.
Atlantic Bigeye Tuna
Thunnus obesus
Bigeye tuna has a mild, meaty flavor, with a higher fat content than yellowfintuna. Sashimi lovers prefer it.
Atlantic Cod
Gadus morhua
Atlantic cod has a mild clean flavor. It is sweeter than Pacific cod.
Frequently Asked Questions
How much protein is in 100 g of Rex Sole?
A 100 g raw serving of Rex Sole provides 12.41 g of protein — roughly 25% of the FDA 50 g daily value.
Is Rex Sole a lean fish or a rich one?
At 70 kcal per 100 g raw, Rex Sole counts as lean on the fattiness spectrum — useful context when deciding cooking method (lean species suit poaching; rich species hold up to high-heat sear).
How should Rex Sole be cooked?
Rex Sole has Tender with fine, firm flakes. — suited to gentle methods that preserve moisture (poaching, sous-vide, low-heat roasting) as much as high-heat techniques (grilling, searing), depending on thickness of the cut.
Sustainability Story
U.S. wild-caught rex sole is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.
Stock Structure
There are three stocks of rex sole: Gulf of Alaska, Pacific coast, and one stock contained in the Bering Sea/Aleutian Islands Other Flatfish Complex. According to the most recent stock assessments: The Gulf of Alaska stock is not overfished based on the assessment of rex sole - Eastern Gulf of Alaska (2022 stock assessment) and rex sole - Western Gulf of Alaska (2022 stock ases…
Population
The Gulf of Alaska and Pacific Coast stocks are not overfished.
Fishing Rate
Not subject to overfishing.
Habitat Impacts
Area closures and gear restrictions protect habitats that are affected by bottom trawls used to harvest rex sole.
Bycatch
Regulations are in place to minimize bycatch.
Management
NOAA Fisheries and the Pacific Fishery Management Council manage the rex 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.
Data Source: NOAA Fisheries
Nutritional Profile
per 100 g raw edible portion · 22 values
Energy
Macronutrients
Omega-3 Fatty Acids
Vitamins
Minerals
Source: USDA FoodData Central (SR Legacy). %DV is percent of 2,000-kcal daily value for adults.
calendar_month Harvest Season
Frozen available year-round.