The Atlantic white-sided dolphin is a mid – large-sized dolphin that can be found traveling in the North Atlantic ocean.
Given its name because of its white belly and sides the Atlantic white-sided dolphin has a visual appeal that stands out when compared to other dolphin species.
These dolphins are a playful species that enjoy traveling together in large groups that can contain several dozen or more dolphins.
When compared to other dolphin species the Atlantic white-sided dolphin appears to be slightly larger in nature than average.
Physical Characteristics and Appearance
When fully grown the Atlantic white-sided dolphin dolphin can reach lengths of 8 – 9 1/2 ft. long and weigh between 425 – 525 lbs. on average with the female dolphins growing smaller and lighter than their male counterparts.
The body itself is often described as being robust in nature and the beak is relatively short when compared to other dolphin species.
They have a long pointed dorsal fin that curves towards the flukes located in the middle of its back and the flippers are small, pointed and sickle shaped.
The flukes are also short but wide in order to help these dolphins propel themselves through the water.
As the name suggests these dolphins have a white under-body that rises along its sides and around its eyes, however the eyes are a dark gray to black color.
They also have an additional white/pale yellow patch along the sides of the dorsal fin, hence the name white-sided.
The back is primarily dark gray or black with a yellow patch and a portion of the beak is also a dark gray to black coloring.
Diet and Hunting Methods
Some of the most commonly hunted fish include hake, herring and mackerel.
To assist with catching their prey these marine mammals have 30 – 40 pairs of teeth that can be used to grab their food in order to prevent it from escaping.
When searching for prey these dolphins have been observed holding their breath for up to 5 minutes during long dives.
Echolocation can also be used to locate prey, coordinate hunting attacks and navigate the ocean.
Given their strong social nature it is quite possible that these dolphins hunt together when searching prey.
Habitat and Migration
As the name suggests these dolphins can be found primarily in the north Atlantic ocean in temperate to subarctic waters that range between 5 – 20 degrees Celsius.
Their range can extend from 35°-80° N of the equator and extend from North Carolina to Greenland.
Large groups of Atlantic white-sided dolphins have been spotted in areas such as Cape Cod, Greenland, the North Sea and the United Kingdom.
They can also be spotted swimming in parts of the eastern United States such as North Carolina as we mentioned before.
In fact large scale stranding have been known to occur in Northeastern U.S. territories, however the cause of these strandings are unknown.
In terms of habitat depth they tend to prefer living in waters that are at least 130 ft. deep (40m.) and can often be spotted in waters that are several times that depth.
As a species the Atlantic white-sided dolphin is often found in offshore waters in and around the Continental shelf making it hard to spot from the local shoreline.
Social Structure and Communication
In certain locations these dolphins have been spotted traveling in pods of up to 60 dolphins.
They have also been observed traveling in small groups of less than a dozen and in pods of up to 500 dolphins.
Atlantic white-sided dolphins are often described as highly social animals that enjoy interacting and playing with one another.
At times they may be seen leaping out of the water or breaching the surface.
As stated earlier these dolphins may be seen associating with other cetacean species such as the fin whale, humpback whale and long-finned pilot whale.
Reproduction and Breeding
The average gestation period for these dolphins is 10 – 11 months.
After birth young dolphins may be nursed for up to 18 months or until they are able to survive on their own.
Sexual maturity for the Atlantic white-sided dolphin occurs between the ages of 6 – 12.
Once sexually mature these dolphins may mate and produce offspring of their own.
The average lifespan of these dolphins is estimated to be between 20 – 30 years.
The Atlantic white-sided dolphin is known to face a number of threats such as being captured by poachers that want to sell their meat, getting caught in fishing/gill nets which can cause these marine mammals to drown and potential life threatening hazards due to water pollution.
Here are some of potential threats the Atlantic white-sided dolphin may face:
- Habitat degradation
- Predators – Killer whales and sharks
While hunting/poaching has been known to exist among the Atlantic white-sided dolphin species (especially in the past) there are no recent studies/assessments done on this topic regarding potential hunting trends and the affect this may have on Atlantic white-sided dolphins.
Bycatch is known to affect some white-sided dolphins as fisheries cast nets and other fishing equipment which these dolphins may end up entangled in.
Once caught in a fishing net these marine mammals become unable to surface for oxygen which leads to drowning.
Given their offshore nature however these dolphins are less likely to face threats from bycatch than other small dolphin species.
As with all marine mammals chemical pollution and waste from metals and plastics can also have an affect on dolphin populations.
Pollution may either harm these dolphins directly or affect their ability to reproduce offspring.
The effects of pollution regarding this species isn’t well understood.
Lastly habitat degradation can have an affect on specific populations where commercialization may occur such as travel routes for passing boats/ships and offshore construction.
Aside from human related threats Atlantic white-sided dolphins may occasionally be attacked by some of the most common predators to the dolphin species which include killer whales and large carnivorous sharks.