The behaviour of Striped dolphins (Stenella coeruleoalba) in the Azores differs from those found in the Mediterranean. In the "Med" Striped dolphins often interact with the boats (e.g. they bow ride), but here in the Azores they appear to avoid us almost all the time.


Striped dolphins travelling - picture taken by Justin Hart (CW Azores Team)

Why this difference in behaviour? We do not yet know, however, the demography and ecology of the species in both seas may give us a clue.
For example in the Med Striped dolphins are the most common cetacean species while in the Azores their numbers are far surpassed by more abundant Common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis).  
Perhaps the difference in behaviour is caused by food competition with the other dolphin species and this leaves them less time for play. The difference in behaviour could also be cultural. Maybe the Striped dolphin population around the Azores still has not learnt to bow ride!

 
Striped dolphins - picture taken by Justin Hart (CW Azores Team)

Sadly, although the Common dolphin is still abundant here in the Azores its population in the Mediterranean is steadily declining, the reasons of the disaster being all related to human activities. The main problem is prey depletion caused by overfishing, and habitat degradation along with pollution are also likely to be play a role.

I wonder how Striped dolphins behaved in the Mediterranean when the Common dolphin was still... common.