The Inter-American Tropical Tuna Commission (IATTC) has been conducting research on the early life history and biology of tropical tunas at the Achotines Laboratory in the Republic of Panama since 1986. Spawning from a population of y ellowfin t una has taken place almost daily in the Laboratory’s land-based tank since 1996 . The near-daily spawning of yellowfin at the Achotines Laboratory represents the only sustained spawning of yellowfin in captivity in the world. In October 2021, the Laboratory reached a milestone of 25 years of sustained spawning of yellowfin.
Eggs and larvae collected from spawning events are used to conduct ecological experiments on early life stages and estimating effects of environmental factors on pre-recruit growth and survival. Pre-recruit research on yellowfin at the Achotines Laboratory has focused on growth and survival dynamics of larvae (first 3 weeks after hatching) , but in recent years the research focus has expanded to the early-juvenile stages (1-6 months). Growth rates have been estimated for all transformation and early-juvenile individuals reared at the Achotines Laboratory in land-based tanks or a sea cage over a 20 year period; the early-juveniles have ranged from 1.6 - 28.0 cm in length and up to 158 days old. Larval growth is exponential in length and weight, and early-juvenile growth is exponential in weight and non-linear in length which when linearized is estimated at 1.0 – 3.8 mm/day . In 2015, in collaboration with Kindai University, the first transfer worldwide of yellowfin juveniles from land-based tanks to a sea cage was successfully completed at the Achotines Laboratory .
The studies of yellowfin growth during the first 6 months have strong application to tuna ecology and aquaculture. Improved rearing success of early-juvenile yellowfin now provides opportunities to study density-dependence in juvenile growth, release tagged early-juveniles in coastal waters of the Panama Bight to provide rare information on pre-recruit movements and distribution, and support the potential completion of full-life-cycle rearing of yellowfin. In this presentation, t he overall growth dynamics of larval and early-juvenile yellowfin will be described, and juvenile rearing studies planned for 2022 will be summarized.