Atlantic spotted dolphin
The Atlantic spotted dolphin (Stenella frontalis ) is a dolphin found in warm temperate and tropical waters of the Atlantic Ocean. Older members of the species have a very distinctive spotted coloration all over their bodies.
The Atlantic spotted dolphin is a medium-sized aquatic mammal found in the warm temperate and tropical waters of the Atlantic Ocean. Its coloring varies enormously as it grows, and is usually classified into age-dependent phases known as two-tone, speckled, mottled, and fused. Calves are a fairly uniform gray-white, with one or no spots. Despite the name, not all individuals of this species exhibit spots on their bodies, though many of them do. However, some dolphins are so densely spotted, that may seem to be completely white from afar. As a general rule, calf dolphins normally lack these spots, developing them as they grow up. On the other hand, those living in the far-offshore waters of the Gulf Stream are often smaller and without spots on their body.
As the name of the species suggests, the dolphin is found in the Atlantic Ocean, occurring in the tropical, subtropical, and warm temperate waters, namely: around the Azores, Canary Islands, Gabon, and Brazil. These dolphins are also widely distributed along the US East Coast, from the Gulf of Mexico to Cape Cod (MA), consisting of 2 stocks: the Northern Gulf of Mexico Stock and the Western North Atlantic Stock. Those, living in the Bahamas, are most often seen in the shallow water above sand flats. On the whole, these dolphins normally prefer waters over the continental shelf, though in some areas the species can also be found in deep oceanic waters.
Atlantic spotted dolphins are highly social animals and gather into groups known as pods. Members of a pod live in close relationships with each other and complex social organization, including individual recognition. Atlantic spotted dolphins are very careful to pregnant females and calves, fiercely protecting them from predators such as sharks. Members of a group also help each other to care for the calves. Within a pod, each individual is ranked depending on its gender, age, size, and other factors. These dolphins may form very small groups, consisting of just a few individuals, and large pods of up to several thousand dolphins in offshore areas. However, pods of Atlantic spotted dolphins rarely include more than 50 animals. Atlantic spotted dolphins are cooperative hunters: they usually hunt in groups at night, using a technique of encircling the prey. They use whistles, cackles, sharp cries and tongue clicking as forms of communication.
Atlantic spotted dolphins are carnivores (piscivores). Their usual diet primarily consists of bottom-dwelling invertebrates, squid as well as fish.
These dolphins have a polygynous mating system, where one male mates with a number of females. The Atlantic spotted dolphins mate throughout the year. The gestation period lasts for 11-12 months, yielding a single baby. The female usually gives birth with the interval of 1-5 years with an average of 3 years. The calf is nursed by its mother for 1-5 years, becoming reproductively mature and starting to breed between 8 and 15 years of age.
Presently, the Atlantic spotted dolphin is threatened by hunting for food and bait along the South American and West African coasts of its habitat, especially in the Caribbean Sea. Besides, the species hugely suffers from fisheries across the area of its range: the dolphins are often entangled in fishing nets, which causes a great mortality among Atlantic spotted dolphins.
According to the NMFS NOAA (National Oceanic and Atmospheric Administration) Fisheries resource, the total population size of the Atlantic spotted dolphin is unknown today. However, there are estimates for specific populations of this species such as the northern Gulf of Mexico stock (24.500 – 31.000 individuals) and the western North Atlantic population (36.000 – 51.000 individuals). Currently, Atlantic spotted dolphins are classified as Least Concern (LC) on the IUCN Red List.