Life history parameters as possible discriminators of bluemouth Helicolenus dactylopterus (Delaroche, 1809) populations in Portuguese waters

The age, growth and reproductive biology of bluemouth, Helicolenus dactylopterus were studied in order to assess the use of these life history parameters as possible population discriminators in Portuguese waters. Fish were obtained from commercial landings in mainland Portugal (Peniche), Azores, and Madeira and supplementary samples were obtained from research surveys in the Portuguese continental slope. Significant differences in mean total-length and mean length-at-age were found between the three areas. The reproductive biology was analysed using the annual sexual cycle, three bionergetic indexes and the maturity ogives. Individuals presented a similar reproductive strategy in Portuguese waters with asynchrony of sexual cycles, similar female spawning season in the three areas and a sperm retention period in the ovaries of 1 to 6-7 months. The bionergetic indexes showed significant differences through the maturative stages and among areas. No significant differences were obtained when comparing the length at first maturity between mainland Portugal and Azores for both sexes. The results of this study will provide a comprehensive understanding of this species life history and presented useful evidence that can support the presence of different populations in the Portuguese waters.