Multiple stock identification approaches of anglerfish (Lophius piscatorius and L. budegassa) in western and southern European waters

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Anglerfish, Lophius piscatorius and L. budegassa, are valuable commercial species distributed throughout the Northeast Atlantic and Mediterranean. This paper examines multiple information (genetic, morphometric, meristic, growth and mark-recapture) on stock structure of anglerfish species from western and southern European waters, to evaluate the suitability of current stocks units (northern and southern). For both anglerfish species, genetic structure showed significant heterogeneity observed mainly between geographically close population in L. piscatorius. More than 98% of the total genetic variation is attributable to differences within populations in both species, which suggest high gene flow within populations. On the other hand, the proportion of total genetic variation between stocks was relatively small. Morphometric characters allowed an acceptable discrimination of samples from certain areas, but not from stocks as a whole. Differences in the growth parameters between stocks was significant, although uncertainties in the ageing criteria diminished the utility of this approach. Tag-recapture experiments proved displacements of anglerfish going through the boundaries of the two stocks. Combined data from genetic, morphometric, growth and tag-recapture studies provide indications that the current geographic separation between the northern and southern stocks is not supported and suggest the existence of discreteness populations along the study area. Given the repercussion of the results in the assessment and management of the two species in the area, more research to improve our understanding of anglerfish stock structure is required.