Global connectivity and interannual fluctuation of genetic diversity in the southern hake population during the last decade

Abstract

Recent p opulation genetics studies on the European hake from the North Atlantic have shown the lack of any stable spatio - temporal genetic structuring between central and southern populations of this species and a broad connectivity precluding any separation betwee n two putative Atlantic hake stocks. This pattern of connectivity studied along three consecutive years consisted of variable migration intensity between populations but fixed migration geometry (North to South Biscay Bay). Since the so - called southern sto ck has shown its minimal historical population size in 2003, as estimated from recruitment figures, it is interesting to exploring the genetic effect that both, the north - to - south connection and its interannual variability have had on the genetic diversity of this southern population. The genetic analysis performed with microsatellites on southern samples from the last decade showed that in spite of the large fishing pressure exerted on this population, its genetic diversity levels remained stable. Such gen etic stability can be explained by compensation between the overfishing - induced genetic drift and the large effective size of its populations. Knowledge on the compensatory forces palliating overfishing of European hake populations would be a great asset t o work out a more focused management of this species.