COMPARATIVE LABORATORY STUDIES OF FEEDING DYNAMICS AND DIGESTION RATES OF YELLOWFIN Thunnus albacares AND PACIFIC BLUEFIN Thunnus orientalis LARVAE  

Maria Stein*, Daniel Margulies, Jeanne Wexler, Vernon Scholey,
Tomoki Honryo, Alvaro Diaz Ortiz, Yang-Su Kim, Yasuo Agawa, Yoshifumi Sawada
 
Inter-American Tropical Tuna Commission
8901 La Jolla Shores Drive
La Jolla, CA 92037 U.S.A.
mstein@iattc.org

The Inter-American Tropical Tuna Commission (IATTC) conducts research on the reproductive biology and early life history of yellowfin tuna (Thunnus albacares) at the Achotines Laboratory, Republic of Panama.  Larvae hatched from eggs spawned at the Achotines Laboratory are routinely used in a variety of laboratory studies designed to investigate the effects of key environmental and biological factors on pre-recruit survival.  

The Fisheries Laboratory of Kinki University, located in Wakayama Prefecture, Japan, has been the world leader in studies of the spawning and rearing of Pacific bluefin tuna (Thunnus orientalis).  In 2002, Kinki University successfully completed the life cycle of Pacific bluefin in captivity, and has continued to expand and refine its studies of the reproductive biology and aquaculture of Pacific bluefin.

In 2011, the IATTC, Kinki University, and the Autoridad de los Recursos Acuáticos de Panamá (ARAP) initiated a 5-year comparative study of the reproductive biology and early life history of Pacific bluefin and yellowfin.  The joint project is being implemented under the Science and Technology Research Partnership for Sustainable Development (SATREPS), and supported by the Japan Science and Technology Agency (JST) and the Japan International Cooperation Agency (JICA).  The joint research is being conducted mostly at the Achotines Laboratory in Panama and the Fisheries Laboratory of Kinki University in Japan.

As part of this collaboration, comparative studies of feeding behavior and digestion rates of yellowfin and Pacific bluefin larvae have been conducted at both facilities.  In this paper, we present the preliminary results from these experiments conducted between 2014 and 2015, including comparisons of the ability of each species to feed exclusively on large prey items at first-feeding, diel feeding patterns exhibited by each species during the first week of feeding, and gastric evacuation rates for both species during the first week of feeding.