The Pantropical Spotted Dolphin (Stenella attenuata) is a species of dolphin found in all the worlds temperate and tropical oceans. This species was beginning to come under threat due to the killing of millions of individuals in tuna purse seines.
The 1980s saw the rise of ‘dolphin-friendly tuna (capturing methods)’ in order to save millions of the species in the eastern Pacific Ocean.
The Pantropical Spotted Dolphin varies significantly in size and colouration throughout its range.
The Pantropical Spotted Dolphin has a slender body, a long narrow beak, and a dark grey dorsal cape and dorsal fin. Light spots cover the dark areas of the body. The lips are white and there is an average of 40 pairs of teeth per jaw. The undersides are pale grey with dark spots. Pantropical Spotted Dolphins can be confused with several other long-beaked oceanic dolphins. Spinner dolphins can be distinguished by differences in dorsal fin shape, beak length, and colour pattern. Atlantic Spotted Dolphins can look similar, but attention to head shape, dorsal fin shape, and colour pattern details will allow correct identification.
In addition to Atlantic Spotted Dolphins, both Bottlenose and Humpback dolphins can also be spotted (generally on the belly) but will be distinguishable by differences in body shape and size. The Pantropical Spotted Dolphin averages 1.7 – 2.4 metres in length and weighs between 90 and 115 kilograms.
Pantropical Spotted Dolphin Behaviour
Pantropical Spotted Dolphins swim in ‘schools’ or ‘pods’ ranging from a few to a few thousand individuals. The Pantropical Spotted Dolphin is very active and is prone to making large splashy leaps from the sea. It is a common breacher and will often clear the water for a second or more. Bow-riding and other play with boats is common.
Pantropical Spotted Dolphin Diet
The Pantropical Spotted Dolphin eats mostly fish and squid in surface and mid-water regions.
Pantropical Spotted Dolphin Communication
Like other dolphins, Pantropical Spotted Dolphins use echolocation, a way of sensing in which they emit high-pitched clicks and sense them as they bounce back off objects (like prey).
Pantropical Spotted Dolphin Reproduction
Female Pantropical Spotted Dolphins reach sexual maturity at 9 – 11 years, males at 12 – 15 years. The gestation period is between 11 and 11.5 months. The calving interval is about 3 years. Lactation lasts 1 – 2 years. The pregnancy rate is estimated at 0.3. It is estimated that the life span of the Pantropical Spotted Dolphin is around 45 years.
Pantropical Spotted Dolphin Predators
Some sharks (including tiger sharks, dusky sharks, and bull sharks) and orcas will prey upon dolphins. Dolphins are also often trapped in fishing nets.
Pantropical Spotted Dolphin Conservation
The IUCN classifies the Pantropical Spotted Dolphin as ‘lower risk/conservation dependent’, meaning there are conservation and management programs in place that address the concerns for this species at this time. The U.S. does not list this dolphin as threatened or endangered.
Pantropical Spotted Dolphin and Humans
The Pantropical Spotted Dolphins propensity for associating with Yellowfish Tuna, particularly in the eastern Pacific has in recent history been a very real danger. In the 1960s and 1970s fishermen would capture thousands of dolphin and tuna at once using purse seine nets. The dolphins all died. Over a period of about 25 years 75% of this regions population, and over half the worlds total was wiped out. The issue has received wide public attention. Many major supermarkets have found it economically expedient to use tuna suppliers whose fisherman catch tuna by more discriminatory means, and now advertise their tuna product as ‘dolphin-friendly’.