Time at risk and No-take areas effectiveness in the South of Portugal

Carmela De Benito

No-take areas (NTAs) have proven to be one of the most effective tools regarding the protection of target species. During the last years several studies have pointed out intra-specific differences in behaviour among individuals of the same population. When developing special conservation tools, such as NTAs, the design has focused on home ranges, spawning, and feeding areas, and migration routes, in the case of migratory species, but taking into account the bulk of the entire population. In this study, conducted in a NTA in the South of Portugal, we determined the different behaviours among a population of white seabream and the differences on the time spent at risk among behaviours, seasons, and diel patterns. Results show how the individuals of this population spent more than half of the time outside the limits of the no-take area and therefore at risk. Although no differences among seasons were observed, some of the individuals evidenced some migratory tendencies likely related to the spawning season. Habitat preferences were observed evidencing the relevance of isolation and habitat discontinuity. This study therefore suggests that not considering the intra-specific differences among individuals of the same population in the design of no-take areas may affect their effectiveness.

Keywords: No-take areas; Marine Reserves; Acoustic Telemetry; Diplodus sargus; Behaviour; Time at Risk, Vulnerability, Isolation, Habitat discontinuity.