Horizontal and vertical movements of the critically endangered Rostroraja alba in a coastal marine protected area

Abstract

Elasmobranchs are slow‐growing marine predators whose populations have declined due to their susceptibility to overfishing, especially affecting species of large size. Rostroraja alba is a large skate that is currently classified as critically endangered. To address the effects of overfishing and promote the recovery of marine species and habitats, marine protected areas (MPAs) are a commonly implemented management strategy. A critical aspect of their success is using information on species' movement patterns; however, this is frequently not assessed for elasmobranchs. In this study, acoustic telemetry was used to monitor 30 R. alba in the Professor Luís Saldanha Marine Park (Portugal) to assess their long‐term movements in the context of a coastal MPA and to evaluate the contribution of this kind of spatial management to the conservation of this species. Immature individuals were more frequently captured than adults, which postulates this area as a potential nursery. The average residency was moderate and relatively consistent throughout the year, as was area use. No marked size or sex‐based differences in movement were noted. Individuals were more active and occurred in shallower waters at night and twilight, and occasional quick vertical movements into the water column, isolated or in sequence, were also noted. In general, the LSMP seems to offer stable protection to immature R. alba, with no strong seasonal variation. These results provide relevant input for adaptive management measures of this and other similar MPAs and highlight the contribution of these efforts to the protection of nursery areas.