Reproductive Biology and Exploited Status of Spawners for Painted Lizard Fish, Trachinocephalus Myops in the Southern Taiwan Strait.

• Main Authors: Yang, Jen-Lee, 楊仁理
• Other Authors: Lee, Yin-Chou
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/50617015803421394592

碩士 === 國立臺灣大學 === 漁業科學研究所 === 86 === The reproductive biology of painted lizard fish, Trachinocephalus myops, in the southern Taiwan Strait was studied from histology. Furthermore, the study evaluated exploiting status of spawners for this species from decrease rate of spawning adults combined with yield isopleth diagram. The results were as follows: (1) Four sexual maturity stages of ovaries were evaluated by naked eyes, i.e., immature, developing, mature and spent stage. Each month had these four stages except February and March. (2) Oocytes development was divided into four stages by histological observation, i.e., immature, developing, mature and spent. (3) A logistic curve was used to fit the relationship between the fraction of maturity and fork length. The minimal mature fork length(ML50) was estimated as 18.0cm for female as well as 18.8cm for male, that is the age of 0.98 and 1.03. (4) The sexual differentiation is apparent for this species. The monthly changes of Gonadosomatic index (GSI) were between 0.17 and 0.64 for female as well as between 0.06 and 0.23 for male. (5) The reproductive activity occurred almost in the whole year. The main spawning seasons appeared in February-April and July-October. The GSI were between 0.52 and 0.64 for female as well as between 0.11 and 0.23 for male in these periods. (6) The monthly variation of condition factor (CF) was same with GSI. The phenomenon implied that the species stocked many nutritions at the reproductive activity, and released them at the end of reproductive seasons. (7) Almost each month can be observed every stages of oocytes development except February and June. That is almost each month has reproductive activity. The phenomenon is also observed from GSI. (8) The fecundity were from 11,075 to 426,240 oocytes for this species. The relationship between fecundity(F) and fork length( FL) as F=6.0000×10-4FL5.8514, r2=0.6932. (9) Sex ratio was 0.5137, which was no significant difference with 0.5 by χ2 test. (10) The age compositions were all 7 age groups, i.e., 0,1,...,6 from 1996 to 1998. The major catch groups were all at age 0. (11) The exploited status of spawners for this species from decrease rate of spawning adults combined with yield isopleth diagram. Showed that all the fishing mortality rates from 1994 to 1998 located above 1/2 curve. In other word, the rate of spawning adults were still under favorable phase.