Use of otolith elemental signatures to unravel lifetime movement patterns of Atlantic spadefish, Chaetodipterus faber, in the Southwest Atlantic Ocean

Abstract

Otolith fingerprinting was used to test the hypotheses that estuarine systems are effective juvenile habitats for Chaetodipterus faber in the Southwest Atlantic Ocean, and that this species displays seasonal migrations between estuarine and marine environments. Adult C. faber were collected in euhaline environments from five Brazilian states (Espirito Santo, Rio de Janeiro, Sao Paulo, Parana, and Santa Catarina) and otolith elemental ratios (Sr/Ca, Ba/Ca and Mn/Ca) were recorded from the core to otolith edge. The otolith Sr/Ca pattern demonstrated that most fish (95%) spend the first year of life within estuaries, but then move toward seawater; migrations between estuarine and marine environments appear not to occur after estuarine egress. Evidence of marine residence throughout life was found in only 5% of individuals. Moreover, the general otolith Sr/Ca pattern indicated that spawning occurs mainly in coastal waters adjacent to estuaries. Additionally, otolith element/Ca ratios suggest that adult C. faber display seasonal migrations between inshore and offshore waters, which corroborate with monthly fishery C. faber landings. This finding implies that artisanal and industrial fisheries require a shared quota. The inferential scope of seasonal movements was sometimes limited by the lack of water chemistry data and unknown relative effects of environmental and physiological factors. Thus additional research is required to evaluate the connectivity between environments, a pre-requisite for effective fisheries conservation and management of C. faber.