1973년 8월 25일부터 1974년 9월 14일에 걸쳐 제주도 서귀포소재 천지천에서 채집한 총 362미의 은어에 대하여 체장, 체중관계와 비만도를 산란기를 중심으로 검토하여 다음과 같은 결과를 얻었다. 1. 체장, 체중관계에 있어 산란전과 산란기에는 그 관계식이 각각 $W=0.008639;L^{3.1806}$과 $W=0.01830;L^{2.7689}$로써 유의성이 인정되었으나 자웅간에는 유의성이 보이지 않았다. 2. 평균체장이 산란기에 감소현상이 나타나는데, 이것은 산란에 참여한 대형어의 폐사에서 온 은어 특유의 현상이라 보았다. 3. 비만도는 산란전인 8월에 평균 $13.45\%_{circ}$ 였던 것이 9월부터 점차로 감소, 11월 29일에 가서 최저로 평균 $10.25\%_{circ}$였으며, 다음 해인 2월에는 $11.18\%_{circ}$로 고복단계에 있었다. 4. 월년어의 대부분은 全전장 $11~12cm$ 미만의 소형어였다.
Three hundred and sixty two specimens of Plecoglossus altivelis were randomly sampled from Chunji Stream in Seogwipo, Cheju-Do, during the period from 25 Aug., 1973 to 14 Feb., 1974 to investigate the relationship between total length and dody weight as well as the condition factor during the spawning period. Results obtained are summarized as follows : The relationships between total length and body weight are calculated as below, respectively : $W=0.008639;L^{3.1806}$ : Prior to spawning period $W=0.01830;L^{2.7689}$ : During spawning period The above equations differ each other significantly. Nevertheless, the significant difference is not found between sexes. The mean body length decreased during the spawning season. The fact seems to be caused by the death of large fish after spawning. The condition factor was $13.45\%_{circ}$ on the average in August. The value decreased continuously from September, giving the minimum mean value of $10.25\%_{circ}$ on Nobember 29. But the value increased again, showing $11.18\%_{circ}$ in next February. Majority of the fish survived until next year was small ranging from 11 to 12cm in total length.
