Short term variations in the number of Japanese sardine [Sardinops melanostictus] eggs collected from the adjoining area of Nagasaki harbor [Japan]
1996
Matsuoka, M. (Seikai National Fisheries Research Inst., Nagasaki (Japan))
Short term variations in the number of collected eggs of the Japanese sardine, Sardinops melanostictus, were investigated. Sardine eggs were collected at the nine stations by plankton net at intervals of one to nine days. Samplings were also carried out every other hour. The total number of eggs collected at the nine stations varied from 2,259 to 4.655/haul in 1988 and from 1,919 to 9.781/l00 cubic-meter in 1989. The number of eggs collected every other hour varied from 148 to 344 and from 11 to 72/100 cubic-meter. The maximum variation of eggs collected at the nine stations was 11.7-20.4 times in 1988 and 5.4-33.8 times in 1989. This result indicates that the number of sardine eggs collected by plankton net changes considerably during short time periods and between adjacent stations, and that the total egg production calculated from spawning survey data may include wide variations
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