2.1 Classification and Distribution The gums are of the order Acridoides, Sphenomorpha, Acrididae, Gingoideae, Gingivalis. The genus of genus is more common in the east and west coasts of South and North America. Nearly 20 species are known, but there is only one type of gingiva on the Asian coast. It is an endemic species on the northeast Asian coast and is mainly distributed in the Bohai Sea, Yellow Sea, and East China Sea. South China Sea and North Korea, Japan, and Russia Far East coast. 2.2 Morphology and characteristics The gingivae are elongated, oval and flat. The eyes are located on the left side of the head. There are small scales on the side of the eye, with dark or black spots, brown, and no white circles on the side of the eyes. The lateral scales 123 to 128 are equally developed on the right and left sides. Tail shank is long and tall. Body length is 2.3 to 2.6 times body height, which is 3.4 to 3.9 times the head length. The ocular side is located in front of the middle of the septum and there is a narrowed flap at the posterior edge of the anterior nasal orifice; the nostrils have two nostrils near the dorsal edge of the head, and the anterior nares have similar flaps. Big mouth, front position. Mouth oblique, symmetrical. The teeth are sharp, tapered, up and down, all equally well developed. The front teeth are large and doglike. The dorsal fin begins approximately near the anterior edge of the upper eye, and the left and right pelvic fins are slightly symmetric, and the caudal fin is double truncated at the posterior edge. Odd fins have dark stripes and pectoral fins have dark spots or horizontal stripes. 2.3 Ecological habits (1) Habitat The gingiva is a cold-water benthic fish with a diverting sand nature. It mostly inhabits waters near the coast with a depth of 20m to 50m, and is mostly sandy, gravel or rocky. zone. Juveniles live in estuarine areas where water depth is more than 10 meters, organic matter is small, and they are easy to form vortex, and they are fattened in summer. When the water temperature drops in the fall, it gradually moves to deeper seas. Generally, in September and October, it moves to the outer sea below 50m. In November to December, it moves south to the depth of 90m or deeper over the sea floor; In the spring, the water depth near the shore is about 30m. The shallow seawater of ~70m breeds eggs. Ginseng can still survive in winter when the water temperature is 2°C, and the lethal water temperature is below 2°C. When the water temperature drops below 1.6°C, juveniles will all die. At water temperatures as high as 33°C, some adult fish can only survive for a short time. The optimum water temperature for the development of gingivae and juveniles is 17°C-20°C. The optimum temperature for adult growth is 8°C-24°C, the optimum water temperature is 16°C-21°C, and the cultured gingiva is below the water temperature 5°C. No feeding, less than 13 °C, 23 °C above the food intake, below 10 °C, 25 °C less feeding and stop growing; water temperature in the range of 13 °C -23 °C with increasing water temperature food intake gradually increased. The gums are widely salty fish and can live in estuaries where salinity is less than 8 。. The tolerance of gingiva to low dissolved oxygen is stronger than that of swim fish such as true bream and fish. The lethal concentration is 0.6mg/L~0.8mg/L, which is lower than the concentration. With the decrease, the incidence will also increase. (2) Ingestion Habits Gingo is a carnivorous fish. Natural larval larvae feed on eggs of invertebrates, rotifers, copepods, and other nauplii, and post-larvae feed on isopods and amphipoda. The larvae of the cleftfooted genus, the larvae of the clefted quagmire, ingested a large amount of copepods at the start of the metamorphosis. The juveniles of the benthic community lived mainly in clams, but also predated sword leeches and other juveniles. After a total length of 3 cm, they gradually turned to predatory sardines. Young fish such as tigerfish. Later began to gradually grow body length 11cm ~ 14cm when the food began to transform, 15 cm of natural food eaten by the gums, nearly 90% of the fish. Juvenile fish and adult fish The types of fish eaten include: juveniles such as squid, scorpion, small goby, bonito, sardine, and squid, and squid. (3) Living habits The spawning period of the gums in various parts of Japan is earlier in the south, and the southern part of the central part is from February to May, and the coast of the Japan Sea is from May to June. The northeastern coast, the land of the Aogu Bay, and Ishikari Bay are from June to July. month. The spawning period of the gums of the Yellow Sea and Bohai Sea coast is from April to June, and the peak period is May. It is a spawning type of fish. The suitable temperature range for spawning is 10°C~21°C, and the optimum water temperature is 15 °C. The wild females of 45 cm to 70 cm in length each have a fecundity of 360,000 to 400,000 eggs. The cultured fish vary in age, and is generally between 900,000 and 1 million grains. Fertilized eggs hatch after 2 days to 3 days. Plankton larvae live in tables and mid-level waters above 20m, at which time the larvae are symmetrical. When the full length is 11mm~12.5mm, the right eye starts to move from the back of the head to the left side of the body, and the right eye moves up to about 16mm to complete the metamorphosis on the left side. (4) The enemy's gums are fierce carnivorous fish, and their adult form has almost no predators. The death caused by predation mainly occurs in the young and juvenile period. At this time, the larger individual's gums, six-line fish and dugong are the main predators, and the death caused by residual food is particularly high. Juveniles more than 30mm in length often use precocious 10mm to 15mm juveniles as prey. Juveniles above 50 mm in natural conditions are rarely fed, but juveniles above 100 mm in size are still preyed.
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