First long‐term study of live observations of loggerhead and leatherback turtles in southern Portugal with relevance for conservation

Most of the information available on loggerhead turtles (Caretta caretta) andleatherback turtles (Dermochelys coriacea) for the southern coast of Portugal isbased on stranding data, and to a less extent on telemetry data, with very littleinformation derived from sightings of live animals.2. This work reports sightings data of loggerhead and leatherback turtles off thesouth coast of Portugal collected during dedicated surveys on board a researchboat, from 2016 to 2022.3. The sightings data corrected for effort confirm the recurrent presence ofloggerhead turtles in the study area, with a higher sightings rate in May and June.Conversely, leatherback turtles were only sporadically observed in some years.4. This study highlights the importance of the southern waters of Portugal forloggerhead turtles as a recurrent area used by individuals of this species, probablyfrom different origins within the North Atlantic and the Mediterranean, in linewith previous studies.5. The southern coast of Portugal, however, is heavily exploited by fisheries, and themain cause of death among sea turtles is bycatch. The results presented willtherefore help inform future management measures aiming to reduce interactionswith fisheries (e.g., limiting some fishing gears in the months with more sightings).6. Since the study area is probably used by loggerhead turtles from differentRegional Management Units, the impacts of conservation measures imposedlocally may also have beneficial effects at a regional scale.

Fundação para a Ciência e Tecnologia - FCT

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