A Study on Growth and Environmental Conditions of Pearl-oyster (Pinctada martensi (DUNKER)).

Present paper refers to elucidate the relation between growth-rate and environmental conditions of pearl-oyster Pinctada martensi (DUNKER)) of Omura Bay. The investigations were carried on May to November 1956 at two pearl-farms in neighboring waters of the Bay ; Ogusi (inside of the Bay) and Segawa (outside of the Bay), occupying two stations in each farm. Two farms above mentioned are hitherto considered by pearl makers to be different in environmental conditions so as to arouse difference in quality of pearls. Results obtained as follows. 1. Growth-rate correlates in positive with water temperature and plankton volume in sea water. 2. It is surmised, the smaller the variations in the dissolved oxygen content and in chlorinity become, the better the shells grow. 3. Gen. Chaetoceros was dominant both in environment and in gastric canal. 4. There is a difference in numbers of bacteria in environment at both farms, but no difference in chemical oxygen demand (C.O.D).1956年6月から11月に亘つて,大村湾周辺海域で生産成績に著しい相異の見られる二つの真珠養殖場に於いて,環境条件の相異の程度を調査し,それとアコヤガイの生長度との関係を見た.1.水温及び環境水のPlankton量と生長度とは正相関する.2.溶在酸素量及び塩素量の変動が小さい程貝の生長はよい傾向がうかがわれる.3.Chaetoceros属は環境水中でも文食餌Planktonとしても優占していた.4.環境水及底質中の細菌数は両漁場で差異を認められたが,可溶性有機物量では差異を認められなかつた