Population structure discovered in juveniles of Greenland halibut (Reinhardtius hippoglossoides Walbaum, 1792)

Understanding the genetic differentiation among populations of most marine fish requires investigating the differences among spawning grounds. However, this can be challenging as spawning grounds for some species are not well known, or spawning fish are difficult to collect. An alternative is to collect juvenile fish in nursery habitats closely associated with potential spawning grounds. Greenland halibut is a deep-dwelling, commercially important species with at least two identified major offshore spawning grounds in the North Atlantic and weak genetic differentiation across the Atlantic. In this study, we sampled juveniles from three sites representing the Davis Strait spawning area in the northwest Atlantic and one site in the northeast Atlantic representing the primary spawning area along the western slope of the Barents Sea. We applied genotype by sequencing and discovered 90 genetic markers that could be used to assess genetic differentiation among the four sites. The northeast and northwest Atlantic showed major genetic differentiation, supporting the existence of the two primary spawning clusters. Additionally, we found genetic differentiation between the three northwest Atlantic samples implying the existence of more than one spawning area in the northwest.

Automated summary

Understanding the genetic differentiation among marine fish populations is challenging due to unknown spawning grounds and difficulties in collecting spawning fish. This study collected juvenile fish from nursery habitats associated with potential spawning grounds and used genotype by sequencing to discover genetic markers for assessing genetic differentiation. The results revealed major genetic differentiation between the northeast and northwest Atlantic, supporting the presence of two primary spawning clusters. Furthermore, genetic differentiation was found among the three northwest Atlantic samples, indicating the existence of more than one spawning area in the northwest.