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Bluefin tuna hatchery success: A first step in resurrecting San Diego, California as the “Tuna Capital of the World” Mariana Michelato, Laura Martinez and Alejandro Buentello, Sr., Ichthus Unlimited San Diego, CA, once was known as the “Tuna Capital of the World” (Ellis, 2008). Following the first tuna cannery startup (1911), the city became a world leader in commerce associated with tuna fisheries. By the 1960s, San Diego’s third-largest economic enterprise would be tuna, superseded only by the U.S. Navy and aerospace, employing over 40,000 San Diegans. After years of overfishing and the tuna embargo, this commerce has all but disappeared from Southern California. In 2016, the National Marine Fisheries Service was petitioned to have the Pacific bluefin tuna, Thunnus orientalis (PBFT), listed under the Endangered Species Act. Assessment by the 2016 International Scientific Committee for Tuna and Tuna-like Species indicated that the stock was “alarmingly overfished”, yet still undergoing high rates of exploitation (Craig et al., 2016). At that time, the Inter American Tropical Tuna Commission also adopted the strictest PBFT conservation measures in history for the Eastern Pacific Ocean (EPO, IATTC, 2016). These actions
combined emphasize the dire situation of the PBFT – and the need for restoration research. Reactive regulatory measures alone have limited capacity to protect endangered populations of fish. While science provides suitable fishery restrictions, implementing these is extremely difficult. The PBFT stock is harvested by several countries and over 80% of the capture occurs in the Western Pacific Ocean (WPO). When forage fish resources at WPO become overexploited, a hunger-driven trans-Pacific PBFT migration is triggered to the EPO (Matsukawa, 2006). Japan’s use of large amounts of wild-caught juvenile PBFT to stock tuna ranches adds to the overall fishing pressure and management complexity. Since tuna ranching started, there has been an exponential increase in the volume of baitfish used to feed tuna in net pens worldwide (WWF, 2005). This is the case in northwest Mexico where most purse seine sardine catches are destined for tuna ranching operations (del Moral et al., 2010). A new assessment delivered to the Pacific Fishery Management Council
Figure 1. Snout hemorrhage after collision (a) and operculum malformations (b and c) are common issues affecting survival in bluefin tuna larviculture.
Hatchery Feed & Management Vol 8 Issue 4 2020