Spawning groups of European anchovy: population structure and management implications

Samples of Engraulis encrasicolus from the western Mediterranean and the eastern Atlantic spawning groups were examined by protein electrophoresis to investigate their relevance in the genetic structure of European anchovy, and how they fit with the current definition of anchovy fisheries. Samples from an earlier study were also included in the analyses to assess the temporal genetic stability of spawning groups. Gene diversity analysis indicated greater differentiation between spawning groups within seas (G(RS) = 0.046) than between seas (G(SEA) = 0.022), and lesser differentiation between locations within spawning groups (G(LR) = 0.003), as well as genetic stability of spawning groups (G(CL) = 0.002). The six spawning groups apparently involved three genetic units according to STRUCTURE results, and the results of other analyses also suggested genetic differences between the two Atlantic spawning groups. The genetic substructure detected within the Atlantic agrees with the spawning groups, but does not fit easily with ICES Subdivisions. Based on these results, a revision of the current anchovy management in both Alboran Sea and Bay of Biscay areas is suggested.