Common dolphins in the Alboran Sea and Gulf of Vera, Spain

In the Alboran Sea common dolphins can fortunately still be seen frequently and in large groups of several hundred. But for how long?

Alnitak has been monitoring the common dolphin in the Alboran Sea since 1992. A study on the genetics of common dolphins shows how a strong gene flow is maintained between common dolphins of Alboran and the Atlantic gene pool, whereas common dolphins east of the Almería-Oran front appear to have little or no connection with Alboran and Atlantic common dolphins.

Apart from the proximity of the Atlantic and its effect on Alboran’s oceanography, this region is the junction of three biogeographic areas, resulting in an extraordinary biodiversity. For the common dolphin, this translates as a remarkable variety of prey species, an important advantage when facing the excessive harvesting of key prey species as the anchovy or the sardine.  

In recent years however, the demand of bait fish from fish farms and especially bluefin tuna fattening farms has promoted the harvesting of new species, previously of no commercial interest. This harvesting has especially affected the Eastern part of the Alboran Sea, the Gulf of Vera.  A maintained decline over ten years of the common dolphins in this Gulf has been highlighted by Alnitak researchers, concerned about the possible link between the fishing down the food chain of local fisheries and the regression of common dolphins.

Another important concern is with regards to other interactions with fisheries, as the bycatch of dolphins in the illegal pelagic driftnets, still being deployed along the coasts of Morocco and Algeria, and the depredation of certain fishing gears by dolphins, which is bringing about a negative response from some fishermen.

Short-beaked common dolphins photographed in the Alboran Sea. Photos © Alnitak.

Cetacean Alliance investigators:

For more information, see:

Canadas A., Hammond P.S. 2008. Abundance and habitat preferences of short-beaked common dolphins (Delphinus delphis) in the South-western Mediterranean: implications for conservation. Endangered Species Research 4:309-331. (3.1 Mb)