北海道宗谷管内のホタテガイの資源とホタテガイ漁場における底生生類群集について

抄録

The author investigated the resources of the scallop, Patinopecten yessoensis JAY, and the benthonic communities of the scallop fishing grounds during the period from May to August in 1962 and 1963 at Sarufutu, Tonbetu, and Esasi in Soya District. On the basis of these results he discussed the fluctuation of the scallop resources after 1960 in these three regions (Table 1), and the composition of the benthonic communities of the scallop fishing ground in June of 1964 at Tonbetu (Table 2). The results obtained are as follows:
1. The scallop resources were estimated by strip-fishing method (Fig. 1) and DeLury's method in these three regions (Table 1).
2. In these three regions the scallop resources tend to decrease gradually, and it seems to be caused by following two factors:
1) Fewer appearance of the youger scallop (Fig. 2); According to the investigations of Hokkaido Fisheries Experimental Station, the younger scallop were always at the head of age distribution after 1955 at Tokoro and Monbetu, where are the main fishing grounds of scallop at present in Okhotsk Sea, Abasiri Dist., Hokkaido.
2) Overfishing; Some years ago, fishing amounts of the scallop were decided on the basis of all estimated resources included them of the outside of main fishing ground.
3. The benthonic communities of all the stations at Tonbetu were dominated by Asterina pectinifera, Asterias nippon, and Strongylocentrotus sp. respectively. The population densities of the scallop were fairly lower than these species at each station (Table 2).
4. According to the correlation method (Motomura, 1935, '52), which was applied to the benthonic composition, the benthos of twenty stations at Tonbetu were divided by those correlation coefficient series into five groups as follows;
Group 1: Asterina pectinifera Community.
Group 2: Asterina pectinifera-Asterias nippon Community.
Group 3: Asterias nippon-Asterina pectinifera Community.
Group 4: Strongylocentrotus sp. Community.
Group 5: Asterina pectinifera-Asterias nippon-Strongylocentrotus sp. Community.
The relation between the scallop communities and above mentioned groups is not clear (Fig. 3).