东海绿鳍马面鲀产卵群体结构和产卵场调查

1.东海绿鳍马面鲀产卵群体自从开发利用以来,体长、年龄和体重组成出现了两次增大两次变小的过程。即1974—1976年和1981—1983年的个体较大,1977—1980年和1984年的个体较小,而1985年的个体最小。但性腺成熟系数却在提高,表明资源的密度在降低。 2.绿鳍马面鲀不同生活阶段的性比不一样,产卵期雄鱼的比例最高,越冬期居次,索饵期雌雄比例基本相等。 3.从产卵个体、仔稚鱼和产卵盛期渔获量的分布判断东海绿鳍马面鲀的产卵场在25°30′—30°00′N、122°00′—126°30′E海区,范围较广,主要产卵场在25°45′—27°00′N、122°00′—123°30′E,水深100—120米的海区。 4.东海绿鳍马面鲀的产卵期在3月底至5月下旬,4月中下旬为产卵盛期。 5.从雌鱼性腺V_A、V_B期比例的周日变化判断绿鳍马面鲀产卵的主要时间在23时至翌日11时。 6.从绿鳍马面鲀人工授精卵附着实验的结果和产卵场环境条件的对照,说明海洋里的贝砾类、海藻、海绵体和珊瑚等物体是马面鲀卵的良好附着基。

INVESTIGATION ON THE COMPOSITION OF THE SPAWNING STOCK AND SPAWNING GROUND OF FILEFISH(NAVODON SEPTENTRIONALIS GUNTHER)IN DONGHAI SEA

1. Since the exploitation of spawning stock of the filefish (Navo-don Septentrionalis Giinther), the variations of its body length, body weight and agecomposition were obvious. The individuals of the stock were big in the years of 1974-1976 and 1981-1983, but small in 1977-1980 and 1984 and smaller in 1985 with carlysexual maturation which showed the declination of the resource. 2. The sex ratio of the fish veried in different seasons. The proportion of malereached to the highest level in spawning period and second in over-wiriter seasonwhile nearly equal to female in feeding season. 3. The spawning ground of filefish covers a wide area from 25°30' N to 30°00'N and 122°00'E to 126°30'E according to the distribution of the spawners, hatchedlarvae and juveniles and catch in spawning season, the area mainly covered from25°45'N to 27°00'N and 122°00'E to 123°30'E. 4. The spawning season of the fish starts from the end of March to the last ten-day of May, the peak period in the middle and last ten days of April. 5. The spewning time of the fish were mainly from 23 p. m. to l1 a. m. nextmorning based on the daily change of the propotions of the ovary stage V_A and V_B. 6. By comparing between the experiment in laboratory the adhesion of the artif-icial inseminated eggs and the natural spawning ground, it showed that gravels, she-lls, seaweeds. sponges and corals were the excellent subetrates for the adhesion ofeggs.