Nippon Suisan Gakkaishi 74 (5), 796-801 (2008)

Augmented biomass of recruits of Japanese Spanish mackerel Scomberomorus niphonius by release of hatchery-raised juveniles as estimated from the larval biomass of Japanese anchovy Engraulis japonica

YASUHIRO OBATA,1* HIDEKI YAMAZAKI2 HIROYUKI TAKEMORI,3
AKIO IWAMOTO,4 KATSUYUKI HAMASAKI5 AND SHUICHI KITADA5

1Tamano Station, National Center for Stock Enhancement, Fisheries Research Agency, Tamano, Okayama 706-0002
2National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, Hatsukaichi, Hiroshima 739-0452
3Fisheries Division, Kagawa Prefectural Government, Takamatsu, Kagawa 760-8570
4Yashima Station, National Center for Stock Enhancement, Fisheries Research Agency, Takamatsu, Kagawa 761-0111
5Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan

We estimated the augmented biomass of recruits from released juveniles of the Japanese Spanish mackerel Scomberomorus niphonius in the eastern Seto Inland Sea based on the biomass of the bait, i.e., larvae of Japanese anchovy Engraulis japonica which is the dominant prey of larvae and juveniles of this species. A total of 51,000 juveniles with a mean total length (TL) of 38 mm and 82,929 with a mean TL of 114 mm were released in 2002; further, 94,000 juveniles with a 36 mm TL and 77,193 with a 96 mm TL were released in 2003. Before release, all the fish were marked on the otoliths with alizarin complexon. Based on the contribution rates of the released fish in the landings, the relationship between the mean weight of 0-year-old fish in November of 1987-2001, and the stock biomass of the bait per 0-year-old Japanese Spanish mackerel, we estimated the augmentation in biomass over natural production to be 30 and 116 tons in 2002 and 2003, respectively.


  [BACK]  [TOP]