Preliminary figures for Japan’s domestic bluefin tuna aquaculture performance in 2020, released by the country’s fisheries agency, showed a decline in the number of farms as well as the volume and number of fish shipped.
The agency has been summarizing the results reported by bluefin tuna aquaculture companies nationwide each calendar year since 2011. 2020 marked the first time in four years that the industry has declined, the agency said.
The number of bluefin tuna farming companies and individual farms each declined by two last year, from 93 to 91, and from 188 to 186, respectively, according to the latest data.
The number of seedlings stocked also declined by 75,000, from 590,000 to 515,000. Of these, the number of natural seedlings harvested from the sea was 320,000, a decrease of 38,000 compared with 2019. The number of artificial seedlings (from closed-cycle breeding) stocked was 195,000, down by 37,000 compared to 2019.
Although the stocking numbers show that the closed-cycle seedlings account for about 38 percent of the total, they make up a much smaller percentage of the mature fish produced, the agency noted. This is because wild seedlings are taken from the sea at about 30 centimeters in length, while the tank-raised seedlings are used in marine farms at just 5 centimeters in length, and mortality at this size is high.
The number of bluefin tuna shipped to market in the year 2020 was 293,000, a decrease of 9,000 from 302,000 the previous year. The total weight of bluefin tuna shipped was 18,609 metric tons (MT), down 979 MT from 19,588 MT a year earlier.
The Minister of Agriculture, Forestry, and Fisheries has set forth a guidance that establishes caps for both the stocking rate and the number of pens, which are set separately for farms employing wild and closed-cycle bred seedlings. Of the 186 aquaculture farms operating in 2020, 75 were restricted to using only artificial seedlings. The remaining 111 farms were limited in the number of cages they could stock with natural seedlings. The purpose of the restrictions is to limit pressure on wild stocks.
Photo courtesy of Piotr Wawrzyniuk/Shutterstock
