|
|
Dover sole fish identification, Habitats, Fishing methods, fish characteristics
Dover sole is a Pacific thick-bodied flatfish of the flounder family which never gets much longer than 20 inches. Landed by trawlers, the species can be found between 400 and 1000 meters deep in cold ocean waters from the North Sea to Africa, it ranges from Baja California to the Bering Sea. Dover sole takes its name from a resemblance to the common sole of Europe, which is often called a 'Dover sole'. It is not a true sole, but a Flounder. Pacific Dover Sole should not be confused with TRUE European Dover Sole which is found in the North Sea to the Mediterranean. They spawn annually in the winter season in deepwater between 800 and 1,000 m. Males begin to spawn at age 4 and females begin to spawn at age 5. Dover sole can live for 45 years and are first available to commercial fisheries at about 6 to 7 years of age. Dover Sole, the premier white, mild-tasting fish with a unique and delicate flavor, is an excellent source of low-fat protein, calcium, and other important nutrients.
|
Dover Sole, Microstomus pacificus, is a fairly large right-eyed flatfish belonging to the family Pleuronectidae, also known as slime sole, Short-finned sole, slippery sole, Smear Dab, , rubber sole, tongue sole, Малорот Тихоокеанский in Russian, is found on the west coast from California to Alaska, Bering Sea and eastern Aleutian Islands to San Cristobal Bay, Baja California. In the eastern Pacific they distributed from Navarin Canyon in the Bering Sea to Stalemate Bank in the Aleutian Islands and San Cristobal Bay, Baja California, Mexico.
|
Description:
The Dover sole is always dextral. It is a slim flounder with elongate, elliptical body; the depth of body is 2.83.2 in standard length. Head is 4.14.7 in standard length. Teeth developed on blind side only, flat and incisor-like, long and broad close set forming a continuous cutting edge, about 10 teeth on lower jaw. This character is differentiate the Dover sole from Deep-sea sole, Embassicthys bathybius, its closest California relative, which differs in having teeth equally developed on both sides.
|
Mouth slightly asymmetrical and small; maxillary reaching just past anterior part of lower eye. Eyes are very large, nearly twice as long as snout, diameter of eye is 3.04.0 in head; lower eye somewhat in advance of upper one, the upper even with profile above. Space between eyes is a narrow, convex, scaly ridge. Gill opening is barely extending above base of pectoral fin to shoulder girdle. Gill rakers short, 8 below angle, 5 or 6 very small scarcely developed ones above. Origin of dorsal fin is slightly behind middle of upper eye; greatest height of dorsal and anal is 2 1/3rd, caudal truncate or slightly rounded; its length is 0.60.7 length of head. Pectoral is shorter than head.
|
|
The scales of the Dover sole are cycloid, very thin, not closely imbricated, somewhat deciduous, and embedded deep in the dermis of the skin; only a small portion of the posterior part is exposed. Scales from the pectoral axilla differ from those found on the more posterior exposed surfaces of the body; they are circular or triangular in shape instead of in the form of an elongated oval. Lateral line is nearly straight except anterior part where it is slightly curved over pectoral fin; a short supratemporal branch, not connected with main lateral line. Mucous secretion is excessive, the fish very slimy.
Key characters
Body elongate with very small scales. Dorsal fin is origin above middle of upper eye. Caudal fin imperfectly rounded. Mouth is very small. Maxillary extends to below anterior of lower eye. Flat and incisor-like teeth developed on blind side only. Eyes large and bulging, with upper eye posterior to lower eye. Anal spine and accessory dorsal branch are absent. Eyed side brown or grayish brown; may be mottled with darker spots. Fins are blackish toward edges. Blind side is smudgy off-white to dark brownish gray. Soft, flabby body is slippery, because of large amounts of slime.
90116 dorsal soft rays
8096 anal soft rays
5054 (usually 12+40) Vertebrae
6 Pelvic fin rays
137146 scales along lateral line
Max length: 30 in (76 cm); common: 40 cm
Max. Weight: 10 lbs (3.5 kg)
Max. Age: 45 years
|
|
On the eyed side, the color varying from a light olive or a dark brown while others indistinctly mottled. A pattern of two yellowish-brown spots along the lateral line, the first just posterior to the pectoral fin, the second half way between the first spot and the posterior edge of the caudal fin. This pattern, most pronounced in small immature specimens, becoming obscure with advancing age, but discernible in some individuals of large size. Some immature fish with five to six small spots equally spaced along the dorsal and anal fin margins. All fins blackish toward the ends of the rays. Blotches of a dull blood-red color common and usually found on the larger fish. Color on the blind side is ranging from a light smoky gray to dark gray. Blotches of the dull red color sometimes found.
There is a tendency for sexual dimorphism in the coloration of the fins in the adults; the males usually have black fin rays while the females show a dark brownish coloration. Also, the general coloration of the males tends to be darker.
Habitats:
Dover Sole are normally found in shallow waters that have a mud or sandy bottom from 30 to 4500 ft (9-1350 m). These fish will often bury themselves in the sand and wait ready for prey. During the summer months of June, July, and August they mainly moved to the moderately shallow depths of 600 ft (180 m) or less, area which is richer in prey on a feeding ground. During the late summer and early fall months they drift toward a bit deeper water. However, in November the outward and downward migration, probably under the stimulus of a spawning urge, becomes a rush, and by December most of the fish moved into depths not usually fished. Here they remain during the peak of the spawning season. By April most of the fish have returned to feeding grounds at about 840 ft (250 m) and continue to move toward to shallow waters for the next three months. This spring inshore migration is not as sharply defined as is the spawning migration; the schools appear to be smaller and less dense and their movements are more sporadic and unpredictable than in the fall.
Dover Soles often feed mostly at night on crustaceans, shrimps, worms and mollusks, small clams, brittle stars (ophiuroids) and snails, small bivalves and scaphopods. Sipunculids, polychaetes, nematodes, echinoids (sea urchins), and gastropods (Thais sp.) and demersel eggs also part of the young fishs diet. Do not eat vertebrate animals. Like the Halibut, these fish are long and flat, almost like someone just ran them over with a steam roller.
Spawning:
Dover Soles became mature at age 7. Males mature earlier than females. Male length at first maturity is 30 cm, at 33 cm 50% of males are mature, and at 40 cm are all mature. Female length at first maturity is 33 cm, at 36-38 cm 50% of females are mature, and at 45 cm are all mature. Females grow faster and get larger than males after age 5.
The spawning season occurs from November to May with heavy spawning pick over December, January, and February. A few spawn in November and March. By February, about 30 percent of the mature females had shed their eggs, and by April practically all of the mature females were spent. Fecundity is about 52,000256,000 depend on fish size, 37,000 to 50,000 (when 36 to 38 cm length and age from approximately 6 to 7 years), 230,000 eggs (when fish about 50 cm. long and from 12 to 15 years old), 265,000 (when large females 57.5 cm total length), 83,000 for 1 kg female. It could be up to 9 spawns per season.
Eggs are buoyant and pelagic, free-flowing, and generally spherical with a small percentage slightly elongated, or "egg-shaped", diameters ranged 2 - 2.57 mm. and average 2.33 mm. They have an undivided yolk without an oil-globule. It takes about 1038 days to hatch. Up to 1 year them staid in larval stage. The young become demersal between 50 mm. and 55 mm. in standard length when juvenile settles out and are found inshore along the bottom. The larvae have a prolonged pelagic life for several months, and metamorphosis is delayed. The distribution is offshore as far as 280 miles. The eggs and young are drift to the south and shoreward due to the existing ocean currents during the spawning season. The Dover sole postlarvae (stage from yolk sac absorption to metamorphosis) can readily be identified and separated from other flatfishes by counts of vertebrae, and the rays of the dorsal, anal, and caudal fins. It is fortunate that these counts are not overlapped by the other species in the same family therefore permitting positive identification.
Fishing:
Dover Sole is a classic wild fish most often caught by fisheries using the trawling method by bottom trawls. Dover Sole, the premier white, mild-tasting fish with a unique and delicate flavor, is an excellent source of low-fat protein, calcium, and other important nutrients is a choice pick for elegant dining during the holiday season. Dover Sole, which yields thin yet firm fillets that hold together well in many preparations. The raw meat is glistening white and dense and stays white during cooking. The flavor of the Dover sole is mild and sweet, elusive and enticingly different from more mundane white fish species.
Dover Sole catch is very low during the winter months, because it moves out into depths at this time of year. Also the winter storms produce poor fishing conditions on the Dover sole grounds, which are far from shore and exposed to the rough conditions of the open sea. At the same time, during the winter and spring, two other more highly priced flatfishes, the Petrale sole, Eopsetta jordani, and the English sole, Parophrys vetulus, move into shallow fishing areas close to shore.
Dover sole escapement is the greatest of any flatfish. First, the Dover sole is very slippery because of the excessive amounts of mucus produced; second, the body is very flexible and can be bent to conform to the openings in the mesh of the nets; and third, there is no interhaemal spine.
|
|
|
