Seasonal Fluctuations in Abundance and Species Composition of Fishes in Cheonsu Bay Using Trap Net Catches

小型定置網資料에 의한 淺水灣 魚類의 水質에 따른 種組成 및 量的 變動

Fish samples were collected by a trap net during 1981∼82 at the mouth of Cheonsu Bay to determine seasonal fluctuations in abundance and species composition. Examination of a series of trap net catches indicated that trap net data could be used, at least, for a qualitative analyses of a fish community and for a quantitative study of some pelagic fishes of Cheonsu Bay. Of the 64 species collected, a few temporal components predominated in abundance because of great seasonal fluctuations of water temperature. The early spring catch showed a low abundance value, and two cold weather seasonals, juvenile Enedrias fangi and Ammodytes personatus predominated in number and in weight. The number of species, abundance value in number and in biomass showed a peak in late spring when fishes move into bay for spawning and feeding after over-winterinig in the sea. Three pelagic species or warm weather seasonals, Harengula zunasi , Ammodytes personatus and Konosirus punctatus, predominated in abundance values. In this period night catch was significantly larger than day catch in terms of number of species, abundance in number and in weight Summer data showed a marked reduction of the number of species and abundance due to the loss of spawners probably by mortality or wide dipersion after spawning. A slight increase in abundance was observed in autumn by recruitment of the young-of-the-years. This catch was predominated by three juvenile fishes, H. zunasi, E. japonica and K. punctatus, which were the same species as in spring. The autumn catch showed no significant difference between day and night compositions.

1981年에서 1982年 사이 淺水灣 入口에서 小型定置網으로 蒐集한 魚類 群集 의 種組成과 量的 變動을 季節別로 分析하였다. 總 64種의 魚類가 採集되었으며, 小數種이 魚類群集을 優占하였다. 이른 봄에는 漁獲量이 적었으며, 베로라치 (Enedias fangi)와 까나리(Ammodytes personatus)가 優占하였다. 魚類의 種數, 個體數 및 漁獲量은 늦봄에 年中最大값을 보였으며, 이는 魚類들이 産卵 혹은 攝餌를 위하여 灣으로 回族하여 들어오기 때문인 것으로 보인다. 이 시기에는 3種 의 乳泳生魚類, 밴댕이 (Harengula zunasi), 멸치(Engraulis japonica) 및 전어 (Konosirus punctatus)가 優占하였으며, 種類, 個體數 및 어획량이 낮에 비하여 밤에 훨씬 많았다. 여름에는 種數 및 漁獲量이 크게 감소하였으며, 이는 産卵후 成漁가 죽거나, 널리 퍼져 있기 때문인 것으로 보인다. 가을에는 그 해에 태어난 魚類가 再介入하여 어획량이 증가하였다. 이 시기에는 봄, 여름에 産卵한 밴댕이, 멸치 및 전어의 幼漁가 우점하였다. 또, 낮과 밤의 種組成도 큰 차를 보이지 않았다.