Arrowtooth Flounder

Arrowtooth Flounder, Atheresthes stomias

The Arrowtooth Flounder, Atheresthes stomias, whose common Spanish name is platija diente fleche and/or halibut del Pacifico, is a member of the Righteye Flounder or Pleuronectidae Family, known collectively as platijas in Mexico. Globally, there are only two species in the genus Atheresthes, one of which is found in Mexican waters, this species from the Pacific.

The Arrowtooth Flounders have elongated fusiform compressed bodies with a depth that is 33 to 37% of standard length. They are gray-brown to olive-brown on their eyed-side and off-white on their blind side. They have a very large oblique mouth that ends beyond their large eyes. Their lower and upper jaws each have two series of large sharp and arrow-shaped teeth. Their anal fin has 72 to 90 rays; their caudal fin is crescent-shaped or slightly lunate; their dorsal fin originates at the middle of the top eye and has 92 to 109 rays; and their pectoral fins are very small. They have 11 or 12 gill rakers on the lower part of their anterior arch. Their lateral line is straight but curves slightly over the pectoral fin.

The Arrowtooth Flounders are found demersal over and within sandy and muddy bottoms at depths between 60 and 2,200 feet. They reach a maximum length of 86 cm (2 feet 10 inches) and a maximum weight of 8.6 kg (19 pounds), with females being significantly larger than males. They are a migratory species found in shallow waters during the summer and in deeper waters during the winter when spawning occurs. They are opportunistic well-camouflaged ambush predators that lie in wait half-submerged on the ocean floor consuming crustaceans (clams, crabs, polychaetes, and shrimp) and fish (cod, herring, and pollock). In turn they are preyed upon by halibut, orcas, sea lions, seals, sharks, skates, and toothed whales. They have a lifespan of up to twenty seven years.

The known range for the Arrowtooth Flounder is from the Bering Sea to Northern California; they are common from Alaska to British Columbia. The fish photographed below is an extraordinarily rare catch of great scientific interest found some 1,000 miles out of its known range and well into the tropical Eastern Pacific.

The Arrowtooth Flounder is most likely confused with the Greenland Halibut, Reinhardtius hippoglossoides (short fat gill rakers).

The Arrowtooth Flounders are very abundant and caught year-round by commercial fishermen utilizing bottom trawls in the Pacific Northwest off the coasts of Oregon, Washington, British Columbia, and Alaska including from within the Bering Sea and around the Aleutian Islands. Currently they are caught an estimated 50,000 tos annually. They are heavily regulated in the Pacific Northwest, but annual catches do not exceed the established limits at present. Management of their populations is deemed to be essential for the ecosystem as they are very abundant and an important part of the food chain both as predator and prey. Their meat can quickly deteriorate if not handled properly giving them a marginal image as a food fish. To increase their marketability, they are sold as “Turbot”, which is a highly esteemed European fish. They are valued commercially for their frills and fleshy fins, which are sold as fake engawa (premium sushi). Whole fish are also exported to China where they are processed into fillets and then reimported into the United States as inexpensive flounder. If prepared properly their meat is delicate and white with a mild sweet flavor. They are also sold as fishmeal, surimi (imitation crab), and animal feed.

Arrowtooth Flounder (1)

Arrowtooth Flounder (2)

Arrowtooth Flounder, Atheresthes stomias. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, April 2013. Length: 54 cm (21 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, CA and reconfirmed by Dr. Robert N. Lea, Monterey, CA.

Arrowtooth Flounder, Atheresthes stomias, gill rakers. A key to the correct identification of this fish.