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- Horizontal and vertical movements of the critically endangered Rostroraja alba in a coastal marine protected areaPublication . Kraft, Sebastian; Winkler, Alexander; Abecasis, DavidElasmobranchs 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. 2. 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. 3. In this study, acoustic telemetry was used to monitor 30 R. alba in the Professor Lu & iacute;s 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. 4. 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. 5. 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.
- Seasonal movement dynamics of the commercially important thornback ray (Raja clavata) in a coastal marine protected areaPublication . Kraft, Sebastian; Winkler, Alexander; Abecasis, DavidElasmobranchs are a group of slow growing species whose populations are in decline mostly due to their susceptibility to overfishing. A common approach to protect marine species is to establish marine protected areas (MPAs). Data on the spatial ecology of species is key information for MPA implementation and management. However, this information is usually lacking, particularly for elasmobranchs. In this study, thornback rays were tagged with acoustic transmitters to track their movement patterns in a marine protected area in Portugal. Individuals were detected for up to 1323 days, and transient and resident behaviours were observed. Residents exhibited a seasonal pattern of presence, peaking during late winter and spring. Weekly occurrence range size reached its maximum from mid-summer to mid-autumn. Diel changes in movement, mainly as increases in activity, were detected during night and twilight. These findings highlight the seasonal and daily dynamics of thornback rays and how these can influence their protection in an MPA. The area where the LSMP is established appears to be dominated by males, indicating that most of the protection provided to this species is towards this sex. These results provide valuable insights for the conservation and adaptive management of this commercially relevant species.