Argyrosomus regius (Asso, 1801) fishery and ecology in portuguese waters, with reference to its relationships to other european and african populations

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultura), Universidade de Lisboa, Faculdade de Ciências, 2014Life history parameters of valuable marine fish remain poorly studied worldwide. The meagre (Argyrosomus regius) is a large sciaenid from European and North African waters that, on its European range, supports regional small-scale and recreational fisheries and is considered a promising candidate species for aquaculture. However, its fisheries and ecology have remained poorly documented. The present work describes (1) progress made on raising scientific and societal awareness on this fish resource, (2) research carried out on the Portuguese fisheries targeting meagre and on the main biological parameters of the species in Portuguese waters. The study of fish remains from archaeological sites showed that both adult and juvenile meagre have been fished in Portuguese estuarine and coastal environments since, at least, the Mesolithic period. Today, two main commercial fisheries on meagre exist: one that targets meagre on the Western coast (within the Tagus estuary and off Peniche); and the other that captures the fish as by-catch in the Southeastern coast of Portugal. Using a new sampling methodology (commercial mark-recapture) a comprehensive set of otoliths and gonads was collected. Analyses of these samples showed that meagre is long-lived (up to 43 years old), displays fast juvenile growth and is reproductively active in spring and summer both in estuaries (Tagus and Guadiana) and adjoining coasts. Furthermore, it shows that both meagre males and meagre females display some signs of precocious maturity and that the meagre females are asynchronous batch spawners that likely have indeterminate fecundity. Moreover, microsatellite work showed that meagre populations in Europe and North Africa are highly fragmented. Finally, a statistical time series methodology is presented (SARIMA) that uses landings under a process control perspective to provided baseline monitoring to fisheries resources currently found in data-poor situation.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/12550/2003, POCTI/MAR/15263/1999 - III Quadro Comunitário de Apoio - 2000-2006); Direção Geral das Pescas e Aquicultura, projeto CORV POCTI/MAR/15263/1999