Humpback whale in the bay of Algeciras and a mini-review of this species in the Mediterranean

Abstract

The presence of humpback whales (MN) (Megaptera novaeangliae) in the Mediterranean Sea has increased for the last 150 years. The reasons why they enter this sea are still unknown and therefore, a review adding new records of the species in the Mediterranean Sea has been considered. Repeated sightings of a young individual have been detected in the bay of Algeciras (Strait of Gibraltar) such that coincided, with stranding events of vast amount of northern krill (Meganyctiphanes norvegica) and species of lantern fish (Myctophum punctatum). Furthermore, data of stranded animals were also added.For all these reasons, the historical presence of this species in the Mediterranean – bypassing its Atlantic migratory routes –, and the theory of why the species occasionally visits this sea has been argued in this paper. Mediterranean sightings map for the species have been developed and overlapped with primary production areas and chlorophyll concentrations in the same sea, finding coincidences between areas of high concentration of productivity and presence of humpback whales. All the individuals detected in the Mediterranean Sea were juveniles or sub-adults (never mother–calf pair), supporting that humpback whales enter these waters for feeding reasons . These solitaire animals may come from their trophic migrations movements rather than the return migration from breeding areas belonging to the North Atlantic populations. Given the increasingly frequent occurrence of these species in the Mediterranean waters, environmental monitoring and conservation programmes for humpback whales should be developed.