Abstract
Sardines generally sampled do not offer enough knowledge of their own living environments. Here the author investigated the growth rate of sardine in relation to the environmental factors. The samples were taken from the Yosanaikai and Kumihama Bay, where larvae of sardine move from the open sea in spring and stay till autumn. The results obtained are summarized as follows.
1). The factor influenced the growth rate of sardine in 1952 is the quantitative and qualitative difference of plankton production in inlets waters.
2). Where the sardines develop into the “Chuba (=middle)-stage”, they migrate to the open sea. At their “Chuba-stage” sardines find their favourable living condition in waters of higher salinity and lower temperature than in inlets waters, to which they adapt themselves at their “Koba(=small)-stage” (Thus classification of sardine according to its growth stages has been widely known among Japanese fishermen. Its ecological importance was recently emphasized by Tsuzita.)
3). As mentioned above, the physiological function of sardine changes essentially in accordance with each stage of its growth, and this physiological change has influence on the ring formation of scales. For instance, many individuals staying in the Yosanaikai for a while after “Chubastage” have two concentric contiguous rings on each of their scales. These rings means continuous physiological change for sardines in adapting themselves to the inlet waters of lower salinity.
