Studies on the Fluctuation in Catch of the Tuna-fishing Fleet―II On the Latitudinal Change of the Hooked-rate of the Albacore and the Striped Marlin in the Fiji Area

摘要

This study is based on the data of fishing conditions collected from the Koyo tunafishing fleet in the Fiji area during three months from September to November 1958, the following results are presumed as to the distribution of the albacore and the striped marlin. 1. In the Fiji area, the former are abundant to the south of 25°S and the latter do between 18°S and 19°S, respectively. 2. The latitudinal change of the hooked-rate of the both fish depend on the seasonal migration. 3. In the regions to the south and to the north of 25°S respectively, tunas have a different biotop and the same is able to say also for the region to the north of 28°S. 4. In the Fiji area where were intense fishing effort as the fleet the followings were seen in each fishing ground;- (1) The hooked-rate at opening of the season was higher than that of the end. (2) The peak of hooked-rate was appwared few days after of hook-number. (3) The hooked-rate, after the suspension of fishing, was higher than the before. 5. The change of the hooked-rate of albacore in this area seemed to relate with the moon age, for instance, the hooked-rate at the spring tide being highest. 6. So far as in the range of optimum temperature, as seen in Table 4, the lower temperature we met the more abundant fish we get.