Genetic investigation of population structure in Atlantic chub mackerel, Scomber colias Gmelin, 1789 along the West African coast

[Data Availability] The following information was supplied regarding data availability: Genotype data is available at Zenodo and Havforskningsinstituttet: Sbiba, S. E. (2024). Microsatellite data on Scomber colias in NW Africa [Data set]. Zenodo. https://doi.org/10.5281/zenodo.11518098 https://imr.brage.unit.no/imr-xmlui/handle/11250/3072605

Sustainable management of transboundary fish stocks hinges on accurate delineation of population structure. Genetic analysis offers a powerful tool to identify potential subpopulations within a seemingly homogenous stock, facilitating the development of effective, coordinated management strategies across international borders. Along the West African coast, the Atlantic chub mackerel (Scomber colias) is a commercially important and ecologically significant species, yet little is known about its genetic population structure and connectivity. Currently, the stock is managed as a single unit in West African waters despite new research suggesting morphological and adaptive differences. Here, eight microsatellite loci were genotyped on 1,169 individuals distributed across 33 sampling sites from Morocco (27.39°N) to Namibia (22.21°S). Bayesian clustering analysis depicts one homogeneous population across the studied area with null overall differentiation (F ST = 0.0001ns), which suggests panmixia and aligns with the migratory potential of this species. This finding has significant implications for the effective conservation and management of S. colias within a wide scope of its distribution across West African waters from the South of Morocco to the North-Centre of Namibia and underscores the need for increased regional cooperation in fisheries management and conservation.

This study was funded by EAF-Nansen project, a collaboration between the Food and Agriculture Organisation of the United Nations, the Norwegian Agency for Development Cooperation, and the Institute of Marine Research in Norway. This project also received support from Global Environmental Facility, as well as the Canary Current Large Marine Ecosystem project, implemented by the FAO, the United Nations Environment Program, and seven partner countries: Morocco, Mauritania, Senegal, The Gambia, Cape Verde, and Guinea Bissau. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Peer reviewed