1Marine Fisheries Research and Development Center, Fisheries Research Agency, Yokohama, Kanagawa 220-6115, Japan, 2National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Kanagawa 236-8648, Japan
The effect of potential factors (fish-hold temperature and period, and biological and product information) on the sales price of bigeye tuna Thunnus obesus in a large-distant-water type tuna longline fishery were examined to clanfy the relationships between fish-market evaluation for the products and these potential factors. We analyzed catch, biological and product information of bigeye tuna caught by a tuna longline vessel whose fish-holds were set at below -50°C and at -40 to -45°C, and the sales price result of the bigeye tuna products in a fish market through a general linear mixed model. The results indicated that the differences of fish-hold temperature and period did not significantly affect the sales price. This means that the fish market (fish broker) evaluated the bigeye tuna products from the -40 to -45°C fish hold as being equivalent to those from the below −50°C fish hold. The model analyses suggested that the sales price was related to richness of fat, mortality, product weight, sex, and blemish of bigeye tunas. We discuss the relationships between the sales price and these factors.