Set Net Catches Of Anchovy, Engraulis japonica(Houttuyn) As Related to Environment

멸치 정치망어획고와 환경과의 관계

The possible effects of several environmental conditions on the catches of anchovy with a set net located in the water off Samchunpo were observed during the period of June 1∼Sep. 30, 1975. The best catches of anchovy were made when the surface water temperature was 24∼25$^{\circ}C$. If the surface temperature were below 18$^{\circ}C$ or above 26$^{\circ}C$, the catches were significantly smaller. The best catches were observed when the salinity was 28∼30 . If the salinities were below 25 or above 33 , the catches were considerably smaller. Increases in the catches were noticed as the transparency of the water decreased for certain range, and the best catches were made when the transparency was 2.0∼2.4m. The catches of anchovy were appeared to be related to the passage of cyclones, and significantly increased catches were observed 2 days after the passage of a cyclone. Significantly increased catches were also made when the atmospheric pressure was higher than 1,015mb under the influence of a tropical maritime air mass. the catches were found to be related to the tidal differences, and the average catch per day during the spring tide was 47 times as much as that of the neap tide.

어황이 해황, 기상, 지형, 해저등의 환경조건에 현저하게 지배받는다는 것은 널리 알려진 사실이다. 그러나 이 방면의 지견은 주로 국지적 어업종사자들의 체험에 기반을 둔 것이 대부분이었으며, Laevastu and Hela(1970)가 이 분야의 연구결과를 정리하여 어장의 형성 및 어황의 변동과 환경요인과의 밀접한 관계를 밝히기까지는 과학자에 의한 연구는 매우 단편적이었다. 멸치, Engraulis japonica (HOUTTUYN)의 생태에 관한 지견은 일반적으로 어민들에게 많이 알려져 있으나 아직까지 멸치의 정치망어획에 영향을 미치는 제 환경요인을 조사분석한 연구보고를 접해 보지 못하였다. 본고에서는 멸치의 정치망어획에 영향을 미칠것으로 생각된 몇가지 환경요인을 약 120일간에 걸쳐 관측하여 어획량의 변동과 비교 검토한 결과를 보고한다.