Genetic structure of selected finfish populations in the Galapagos Islands, Ecuador

Abstract

The genetic structure of selected five finfish populations, namely, almaco jack (Seriola rivoliana), sailfin grouper (Mycteroperca olfax), stalkeye scorpionfish (Pontinus strigatus), wahoo (Acanthocybium solandri) and yellowfin tuna (Thunnus albacares) in the Galapagos Islands, was studied using mitochondrial DNA cytochrome b (797 bp) and D-loop (426 bp). The results of the present study showed that (1) almaco jack, yellowfin tuna and wahoo had high haplotype diversities and numerous singleton haplotypes and spread over extensive ranges, as expected in pelagic fishes, while only Galapagos yellowfin tuna from D-loop dataset showed population expansion (P < 0.05); (2) sailfin grouper cyt b had low haplotype and nucleotide diversities, confirming the concern from previous study that the fish was overfished in waters off the Galapagos Islands. It further supports the need to effectively manage sailfin grouper; (3) Stalkeye scorpionfish cyt b had also low haplotype and nucleotide diversities, but with significant negative Fu’s Fs, (P < 0.01), indicating genetic hitchhiking and overall reduction of genetic variation, supporting the need to monitor stalkeye scorpionfish; and (4) no genetic differentiation was found between Galapagos and Western Pacific yellowfin tuna (P = 0.9). The singleton haplotypes specific to the Galapagos yellowfin tuna population might indicate reproductive isolated units or founders. The results provide an insight into the genetic structure of finfish populations, which can be used to draw an effective management plan for ensuring their long-term sustainability in the Galapagos Islands.