| Summary: | Tese de Doutoramento em Biociências apresentada à Faculdade de Ciências e Tecnologia Accurate knowledge on the organization of marine species along their geographical distribution is key for fisheries science, management and conservation policies. Over the last decades, several stock identification methodologies have been developed and improved to further unravel fish population structure and connectivity, considering that fish stocks are the basic units for fisheries management. From the wide range of artificial and natural markers available for stock identification, otolith-based approaches are among the most used methods. Their broad and successful application is related with both otolith shape and chemical composition which are influenced by environmental conditions of the surrounding habitat and life history traits of each species, allowing the identification of discrete population units along a species distribution range.The aim of this PhD thesis is to disentangle the population structure of three highly valued commercial marine fish species: blackbelly rosefish (Helicolenus dactylopterus), European hake (Merluccius merluccius) and common sole (Solea solea) along their geographical distribution range in the Northeast Atlantic Ocean and Mediterranean Sea. For this purpose, a combination of otolith-based methods, namely otolith shape and otolith chemistry, was used to investigate their applicability and efficiency as natural markers for the identification of fish populations, as well as their concordance and/or complementarity.The first approach was based on otolith shape analysis. This technique allowed distinguishing several discrete population units, but with distinct resolution for the three species. While all sampled populations demonstrated a high overlap within the Northeast Atlantic Ocean, the blackbelly rosefish showed a more structured stock organization when compared with the other species, most probably due to its more sedentary lifestyle. In the Mediterranean, a clear distinction between ...
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