Using body geometric morphometrics to identify bluemouth, <Emphasis Type="Italic">Helicolenus dactylopterus</Emphasis> (Delaroche, 1809) populations in the Northeastern Atlantic

In this study, landmark-based geometric morphometric methods were applied to evaluate the possible existence of different bluemouth, Helicolenus dactylopterus (Delaroche, 1809), populations in the NE Atlantic. Fish were obtained from commercial landings in Azores, Madeira, and Peniche (mainland Portugal). Samples from a research survey along the Galician coast (Spain) were also included in this study. A generalized procrustes analysis was done to remove non-shape variation. Then, the obtained shape variables were statistically adjusted to eliminate allometry and permit a comparative analysis of the samples. The discriminant analysis performed to test the homogeneity of the data set regarding sex revealed no shape differences between males and females within the four areas under study. The body shapes of bluemouth differed significantly among the four areas using Procrustes distances (P < 0.01). In this study, a considerable morphological heterogeneity within the Azores group was observed, which could reflect a substructure of the bluemouth population within this area. According to our results, bluemouth from Galicia and Peniche seem to be relatively well separated from each other, despite both areas are relatively close geographically. Bluemouth from Madeira was well differentiated from the rest of locations and presented the highest correct classification rate in the discriminant analysis. In conclusion, morphological differences suggest that different bluemouth populations exist in the NE Atlantic, but an integrated approach, using different methods, would be needed to confirm the population structure of this species.