Spawning ecology of captive yellowfin tuna broodstock inferred by the use of mitochondrial DNA sequencing analysis

Abstract

Genetic monitoring was conducted on a yellowfin tuna Thunnus albacares (YFT) broodstock population held in a land-based facility at the Inter-American Tropical Tuna Commission (IATTC) Achotines Laboratory. The number of females contributing to a single spawning event were identified and their spawning quantity and periodicity were monitored by the analysis of the mitochondrial DNA (mtDNA) D-loop region. There were 50 broodstock YFT in the tank during the study period of 2011-2014. By comparing broodstock mtDNA sequences against 555 offspring eggs it was possible to identify at least 11 broodstock females that spawned during the study period and identify the most fertile individuals. Multiple females participated in single spawning events. An individual female spawned every month for a period of 1.5 years, supporting the concept that YFT females in captivity are capable of spawning for extended periods of time. Another individual female spawned intermittently for about 26 months. The results demonstrated that the D-loop region of YFT displays enough variation to discriminate among individuals and highlights the value of molecular biological approaches in elucidation of the spawning ecology of wild YFT populations and in the management and selection of tuna broodstock for aquaculture purposes.