1Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164-8639, 2Faculty of Fisheries, Nagasaki University, Nagasaki, Nagasaki 852-8521, Japan, 3Inter-American Tropical Tuna Commission, Scripps Institution of Oceanography, La Jolla, CA 92037, U.S.A.
Tank experiments were conducted to study the effect of oceanic turbulence on the survival of first feeding larvae of yellowfin tuna. Several levels of turbulence intensity were provided by changing the amount of air bubbles released from air−stones in the tanks containing yellowfin tuna larvae. The results showed that there is an optimal turbulence intensity which enhances larval survival. This turbulence intensity was equivalent to approximately 1−2×10−8 m−2s−3 as an energy dissipation rate, suggesting that the surface mixed layer of equatorial oceans used for spawning by the yellowfin tuna is a suitable environment for the survivals of larrae.