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Gonçalves Jardim de Freitas Araujo, Teresa Mafalda
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- Deep Sea Chondrichthyes from Madeira and Nearby Seamounts (NE Atlantic)Publication . Araujo, Teresa Mafalda Gonçalves Jardim de Freitas; Kaufmann, Manfred JosefChondrichthyes play a key role in the ecological balance of the ecosystems as predatory species. However, more than one-third of these species are threatened by overfishing. The lack of information on chondrichthyan species in the archipelago of Madeira led to this study, which intended to provide reliable information on their taxonomy, biology, population dynamics and fisheries. An updated checklist of cartilaginous fishes, new records, taxonomic annotations, and clarification as well filling the gaps on life history of several species were accomplished during this thesis. The checklist confirmed the presence of 67 species of sharks, rays, and chimaeras. Another 14 species previously referred for the area are now considered dubious records, and 5 species are withdrawn from the list. Centrophorus uyato is here recorded for the first time from Madeira. Of the species reported 24 are in the list of threatened species according to the IUCN European Red List of marine fishes. Hydrolagus affinis and Chimaera opalescens are also first recorded for the Madeira region, and their known range of distribution are extended. The clarification and resolution of uncertainties over the identification of Deania calcea and Deania hystricosa were accomplished through morphological and molecular studies, that confirm that both are the same species. The knowledge of fish diversity of several seamounts belonging to Madeira-Tore complex at different depth strata down to 2500 m was increased, bridging the information gap regarding seamount associated elasmobranchs. The checklist of cartilaginous fish species for Seine and Unicorn seamounts confirmed the presence of 17 species in Seine and 11 in Unicorn, corresponding to about 31% of the valid Chondrichthyes reported for the archipelago of Madeira. The work herein presented contributed to increase the knowledge of fish communities, diversity, and occurrence of Chondrichthyes in the archipelago of Madeira. A reliable overview of Madeira’s elasmobranch fisheries and their evolution, between 1990 and 2020, is also provided. The study on the biology and population dynamics of Centrophorus squamosus allowed to verify that the pressure of fishing did not cause critical changes in the life history parameters of the species over 22 years. The information obtained is essential to obtain the geographic distribution and depth of the species, as well asto evaluate the fisheries impact on the biology and population dynamics of this group, aiming to contribute to the development of suitable management strategies to preserve these species, specifically the populations under pressure by the Madeiran longline artisanal fishery.