鸭绿江上游花羔红点鲑的年龄_生长_食性和繁殖的研究

花羔红点鲑的鳞片年累特征为疏密一切割混合型。体长和体重关系密切，属均匀性生长类型。主要以水生昆虫为食，对食物有明显的选择性；主要摄食季节为夏秋两季，但可终年摄食。雌雄鱼几乎２＋龄达到性成熟，产卵期为１０￣１１月，绝对繁殖力为２８０￣５００粒，每年产一次卵，属秋季产卵类型。产卵场底质为石砾，水深５０￣７０ｃｍ，水流速度１．５￣２．０ｍ／ｓ，水温一般为５￣８℃。

STUDIES ON AGE, GROWTH, FEEDING HABITS AND REPRODUCTION OF THE SAL VELINUS MALMA IN THE UPPER REACHES OF THE YALU RIVER

Sca les w ere used fo r the age determination. The annua-l r ing f eature belongs to the lo oseclo se and cut pa tter n. The a nnua-l ring is f ormed chiefly fr om Oct ober to December . The Do lly va rden charr , Salvelinus mal ma fe eds ma inly on aquatic insects, a nd on small ter re str ial a nimals and o thers. Feeding takes pla ce mainly in summer and aut umn, but it ma y be obser ved a ll the year r o und. Mo st of the fem ale s and ma les r each the f ir st m atur ity in the a utumn o f their thir d y ear o f lif e, although some may r each the first maturity in sec ond y ear . The spawning too k place fr om Octo be r to No vem ber and the individual absolute fecundity r anges fr om 280 to 500 eg gs. Fish spawns o nce in a ye ar in aut umn. The enviro nmental conditio ns of the spaw ning g ro unds need gr av el in the bo ttom, 50~ 70 cm in w ater depth, 1. 5~ 2. 0m/ s in wate r f low ing speed and 5~ 8 e in w ater temper tur e.