Scrutinizing the current management units of the greater argentine in the light of genetic structure

Abstract

The greater argentine is a benthopelagic fish with a northern amphi-Atlantic and southern Arctic distribution. Landings of this species have been steadily increasing since the early 2000s, mainly for ultra-processed fish food. The rising economic importance of this species begs for an accurate delineation of the management units needed to ensure the sustainability of the fishery. The alignment between management and biological units was investigated on three of the ICES stocks in the NE Atlantic (123a4, 5a14, and 5b6a) by genotyping 88 ad hoc-developed SNPs on 1299 individuals sampled along the Norwegian coast, north of Shetland, around the Faroe Islands, and in the Denmark Strait within Icelandic waters. Candidate loci to positive selection were particularly crucial for units’ delineation and supported the current ICES 5b6a and 5a14 stocks around the Faroe Islands and Iceland, respectively. However, within the third stock investigated, 123a4, which corresponded mainly to the Norwegian coast, the sample from area 3a (Skagerrak) was significantly different from all the remaining in the same stock. This differentiation advocates for reconsideration of the present policy and suggests considering ICES Area 3a (Skagerrak) as an independent management unit. The environmental conditions in the Skagerrak area have left a genetic print on other marine taxa, which could putatively be the case in the greater argentine.