Abstract:

Characteristics of reproductive biology of 〖WTBX〗Tridentiger trigonocephalus〖WTBZ〗 at the Yangtze estuary were studied. The results show as follows:(1)Morphological traits between male and female 〖WTBX〗T.trigonocephalus〖WTBZ〗 are different.Relative fatnesses of male and female 〖WTBX〗T.trigonocephalus〖WTBZ〗 are 347±036 and 217±052,respectively.The ratio value of body length and body height,body length and head length,head length and eye diameter,head length and eye distance have significantly different between male and female.(2)〖WTBX〗T.trigonocephalus〖WTBZ〗 spawns in the summer from March to July,and main from April to June.The individual absolute fecundity is 12 6892 eggs and body length relative fecundity is 2069 eggs/mm.(3)The egg is circular and its diameter ranges from 0482 to 0606 mm.The sperm consists of round head with 098±012 μm of the long diameter and 728±106 μm flagellum.(4)〖WTBX〗T.trigonocephalus〖WTBZ〗 spawns in burrows and the nest will be protected by male fish.(5)The shape of fertilized eggs looks like a pear or a shuttle and there is an adhesive filament disc on the external eggmembrane of the animal pole. Fertilization rate under artificial and natural condition are 7858% and 8384%,respectively.Normally,embryo can develop under the temperature condition from 17 to 25℃ and hatch time depending on water temperature.In theory the sum of effective temperature of embryonic development is 3 1283 h·℃.Reproductive biology and abundance of 〖WTBX〗T.trigonocephalus〖WTBZ〗 may be affected by environment change of the Yangtze River estuary.

Key words: Tridentiger trigonocephalus/ morphological traits/reproductive biology/spawn/oosperm/embryonic development