MEPS prepress abstract  -  DOI: https://doi.org/10.3354/meps12449

Contemporary migration of fin whales through the Strait of Gibraltar

Pauline Gauffier*, Philippe Verborgh, Joan Giménez, Ruth Esteban, Juan Manuel Salazar Sierra, Renaud de Stephanis

*Email: pauline@circe.info

ABSTRACT: Fin whales Balaenoptera physalus used to be abundant in the Strait of Gibraltar and nearby Atlantic areas until their rapid collapse due to intense whaling at the beginning of the 20th century. Recent studies seem to indicate that some fin whales, believed to belong to the North East North Atlantic (NENA) stock, use the area nowadays to travel between the Atlantic Ocean and the Mediterranean Sea. In this study we analyze 15 years of direct observations combining vessel and land-based surveys with photo-identification to characterize the migration of fin whales through the Strait. These combined observations provide a temporal and spatial analysis of the whales’ movement patterns, as well as their behavioral activity. Our main findings suggest a migration of a small community of fin whales through the Strait of Gibraltar, with remarkable seasonal directionality. All whales travelled towards the Atlantic Ocean in May-October and 69% towards the Mediterranean Sea in November-April. Observations of young whales exiting the Mediterranean Sea mainly in May-July suggest that at least part of this community is likely to calve in the basin. Due to the special sensitivity of the species to ship strikes and underwater noise and the intense maritime traffic in the Strait of Gibraltar, we urge Spain and Morocco to cooperate through the International Maritime Organization (IMO) to ensure a safe crossing of these whales by the effective implementation and extension to the rest of the year of the existing recommendation of a seasonal vessel speed reduction to 13 knots.