Cruise passengers spot an odd one
Passengers on a cruise in Akaroa Harbour have been treated to a rare sighting of a lone short-beaked common dolphin.
The unexpected marine mammal was spotted ‘‘cruising along’’ with a pod of about 20 Hector’s dolphins on Saturday, Black Cat Cruises’ skipper Hamish Crosbie said.
The species was, as its name suggested, common, although not in Akaroa Harbour. It was normally found in the North Island and South Island sightings were more likely in Kaiko¯ ura and Milford Sound, he said.
‘‘We see short-beaked common dolphins in Akaroa Harbour once a year at most. The last time we sighted a short-beaked common dolphin there was a pod of about 200 cruising up the harbour, so it is very unusual to see just one.
‘‘We assume this one has joined this pod [of Hector’s dolphins] for protection or to find food.’’
Crosbie said it was ‘‘quite a rare occurrence’’ for dolphins to swim in mixed groups, although the Department of Conservation’s (DOC) website said short-beaked common dolphins were ‘‘known to associate with schools of pilot whales and other dolphin species such as dusky dolphins’’.
‘‘Dolphins have complex relationships and most of the time they will co-operate by socialising and playing,’’ Crosbie said.
According to DOC’s website, short-beaked common dolphins were usually found in offshore warm-temperate waters in the Atlantic and Pacific oceans.
In New Zealand they tended to remain a few kilometres off the coast. They were often in the Hauraki Gulf and off the coast of Northland.
They have distinctive colours – purplish-black, grey, white and yellowish tan – with criss-cross or hourglass-type patterns centred on their flank.
Their dorsal fins are high with concave hind edges.
They eat surface-schooling fish, small mid-water fish and squid, and are known to form enormous schools several thousand-strong.