臺灣海峽南部產短吻花桿狗母魚之成熟、產卵，及產卵親魚利用現況之研究

Abstract

本研究以組織學方法探討臺灣海峽南部產短吻花桿狗母魚（Trochinocephalus myops）的成熟與產卵等生殖生物學研究，並以產卵親魚減少率結合等漁獲曲線來評估產卵親魚的利用現況，其結果如下： (l)裸視判斷卵巢成熟度可分為未發育、發育中、成熟及排卵後四期，顯示除二、三月份外，其餘月份皆含有 此四期的卵巢。 (2)由卵巢的組織學切片，將卵發育階段分成，未成熟(包括染色絲核仁期與週邊核仁期)，成熟中(包括卵黃泡 期、卵黃球前期與卵黃球後期)，完熟(包括卵核移動期、卵核破裂期、排卵前期、排卵期及產卵期)與退化 期(包括各期之退化卵)。 (3)以50％成熟比率(ML50)決定雌、雄魚之最小成熟體長，分別為18.0cm及18.8cm，相當於0.98及1.03歲。 (4)雌、雄魚的兩性分化明顯，雌魚的月別生殖腺指數介於0.17-0.64之間，雄魚的生殖腺指數介於0.06- 0.23之間。 (5)由雌、雄魚的生殖腺指數之月別變化顯示本種魚的生殖期相當長，幾乎終年都有生殖行為。生殖的高峰約 在2-4月及8-10月，這段期間雌魚的生殖腺指數為0.52-0.64，雄魚的生殖腺指數為0.11-0.23。 (6)由雌、雄魚的肥滿度的月別變化得知，肥滿度變動與生殖腺指數變動一致，顯示本種魚在主要生殖季節期 間蓄積了許多營養使肥滿度上升，生殖季節接近尾聲時，由於排卵(精)活動的大量耗能使肥滿度下降。 (7)經由各月卵巢切片發現除了2、6月份外均含有各期成熟之卵粒，顯示每月皆有排卵現象，與由生殖腺指數 推測每月均有生殖活動的現象相符。 (8)雌魚的總孕卵數為11,075至426,240個卵粒，尾叉長(FL)與總孕卵數(F)之間的關係為F=6.0000×10- 4FL5.8514，r?=0.6932。 (9)由採樣所得2,256尾樣本魚的雌、雄魚性比為0.5137，經卡方檢定與0.5無顯著差異。 (10)年齡組成的估計結果顯示1996、1997及1998年三年均含0，1，…，6歲等七個年齡群，主要漁獲年齡均為 O歲。 (11)等漁獲量曲線圖套合產卵親魚減少率顯示1995,1997及1998年的瞬間漁獲死亡係數在產卵親魚減少率1/2曲 線的上方，表示產卵親魚處於理想的狀態；1994及1996年的瞬間漁獲死亡係數在產卵親魚減少率l/2與l/3 曲線之間，表示產卵親魚處於須要注意的狀態。

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, r?=0.6932. (9)Sex ratio was 0.5137, which was no significant difference with 0.5 by x?test. (1O)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 of 1995, 1997 and 1998 located above 1/2 curve as well as that of 1994 and 1996 located above 1/3 curve. In other word, the rate of spawning adults were still under favorable phase in 1995,1997 and 1998.However, the rate of spawning adults of 1994 and 1996 were under cautious phase.