Fecundity characteristics of cuttlefish Sepiella maindroni along the coastal waters in Zhoushan
LIU Lianwei,SUI Youzhen,XU Kaida,XU Xiaoxuan,LIU Shuhan, XIE Muyuan,XU Hanxiang,ZHOU Yongdong
1.Scientific Observing and Experimental Station of Fishery Resources for Key Fishing Grounds,Ministry of Agriculture and Rural Affairs,Key Laboratory of Sustainable Utilization of Technology Research for Fisheries Resources of Zhejiang Province,Zhejiang Province Key Laboratory of Mariculture and Enhancement,Zhejiang Marine Fisheries Research Institute,Zhoushan 316021,China;2.Marine and Fisheries Institute,Zhejiang Ocean University,Zhoushan 316022,China
Abstract: Individual fecundity including potential fecundity and relative fecundity was investigated in the cuttlefish Sepiellamaindroni collected from traps in Mopanyang Sea,Southeast of Liuheng Island,Zhoushan,Zhejiang,April 2021 (spawning season) via measurement of mantle length,body weight,gender,gonadal development and weight,gonadosomatic index (GSI),nidamental gland index (NGI),and spermatophoric complex index (SCI).Also,the relationships between potential fecundity (Fp) and the biological indices were analyzed by using mathematic regression equations in order to indicate the reproductive strategy of the cuttlefish.The results showed that the cuttlefish had dominant mantle length of 91-130 mm and dominant body weight of 120.1-240.0 g in female and dominant mantle length of 81-120 mm and dominant body weight of 80.1-180.0 g in male along the coast waters of Zhoushan,with very significant differences in mantle length and body weight between females and males (P<0.01).The female and male individuals were all primarily at maturity stage of Ⅴ phase,accounting for 68.63% and 65.35%,respectively,with significant correspondence between GSI and NGI or SCI (P<0.05).Average Fp and average relative fecundity by mantle length and body weight of mature female individuals were estimated to be (1 121.01±329.55) cells,(9.76±2.43) cells/mm and (5.77±1.28) cells/g,respectively.Fp showed a power regression on mantle length,body weight and the nidamental gland weight,and a logarithmic regression on the nidamental gland length as well as a linear regression on GSI of ovary.Average Fp and average relative fecundity by mantle length and body weight of male mature individuals were estimated to be (2 769.48±1 195.90) spermatophores,(26.38±11.02) spermatophores per millimeter,(19.82±8.66) spermatophores per gram.Fp showed a exponential regression on body weight,and a power regression on the length and weight of spermatophoric complex,without significant regression of Fp on mantle length and GSI in testis (P>0.05).The results indicated that there was decrease in Fp and the ratio of sperm to egg ten years before stock enhancement of S.maindroni and reasonable parental sex ratio should be put in large-scale of the cuttlefish to make sure reasonable potential ratio of sperm to egg.
2022, Vol. 37 
