Marine Mammal Research Organisation - Part 1 - Dolphins

Marine Mammal Research Organisation - Part 1 - Dolphins

  • Description
Set: Part No: ST011713
Set: CTO: ST011714
Set: FDC: ST011715
The Bahamas Marine Mammal Research Organisation (BMMRO) is a Bahamian non-profit organisation whose mission is to promote the conservation of marine mammals in The Bahamas through scientific research and educational outreach. Since 1991, BMMRO has been conducting small vessel surveys primarily around Abaco Island to document the occurrence, distribution and abundance of marine mammals in The Bahamas. The majority of species found here are deep diving toothed whales that inhabit the pelagic waters surrounding the shallow Bahama banks. Some migrate through The Bahamas, but many species are year-round residents, including some of the world’s least known whales. By photographing the pattern of natural nicks and scars on each animal’s dorsal fin or tail flukes, a technique known as photo-identification, we are able to keep track of individuals - gaining an understanding of their population demographics, reproductive success, and social structure. BMMRO’s field work has expanded over the past ten years to include larger vessel surveys in the Great Bahama Canyon, including at the US Navy’s Atlantic Test and Evaluation Center in Tongue of the Ocean, where use of tactical sonars potentially pose a risk for some species. This work has provided a wider picture of marine mammal distribution in the northern Bahamas and have aided in identifying important areas for deep-diving whales. Genetic studies and pollutant analyses have helped to identify stocks and will allow further investigation of the health of local populations. Through on-going partnerships with universities and oceanographic institutes, BMMRO has many new projects underway including the use of time-depth recording tags to investigate beaked whale foraging behavior and hexacopters to photograph whales to assess their health.

Pantropical spotted dolphins (Stenella attenuata) are more slender in body shape than Atlantic spotted dolphins, and also have a distinctive dark dorsal cape, which sweeps from their rostrum to behind their dorsal fin. Like Atlantic spotted dolphins, they accumulate their spots with age, which allows researchers to readily document age-classes within groups. This species is strictly oceanic in its distribution. Pantropical spotted dolphins are not as frequently sighted as Atlantic spotted dolphins in The Bahamas. They occur in groups of 50-100 dolphins and are often seen engaging in acrobatics, such as making high leaps out of the water, and bow-riding.

Bottlenose dolphins (Tursiops truncatus) are the most common marine mammals seen on the Bahama banks. It should be noted, however, that there are at least two distinct “breeding populations” or “ecotypes” of this species: coastal bottlenose dolphins that inhabit the shallow waters of the banks; and, oceanic bottlenose dolphins found in pelagic waters. These populations diverged genetically several hundred thousand years ago and have since developed different physiological adaptations to their respective marine environments. The coastal ecotype is smaller in length reaching just over 8 feet and has a relatively larger dorsal fin and pectoral fins which helps them to maneuver more readily around rocks and reefs to catch fish, and to regulate their internal body temperature (the temperature of the shallow Bank waters fluctuates much more than the deeper Atlantic Ocean). The coastal dolphins do not travel much beyond the bank edge and live in small resident communities. The deeper diving oceanic ecotype can reach 10 feet or more in length, are usually seen in larger groups and appear to have a more extensive range with movements documented between Abaco, Bimini and Exuma Sound.

Atlantic spotted dolphins (Stenella frontalis) are not born with spots, but actually accumulate them as they mature, becoming quite mottled-looking as adults. Hence, young spotted dolphins are often confused with bottlenose dolphins, and sometimes the two species will interact, which adds to the confusion. Although they can reach almost the same length as bottlenose dolphins, they have a smaller girth and thus body weight. Atlantic spotted dolphins are a year-round resident species in The Bahamas. Individuals photo-identified 20 years ago in Abaco can still be seen in the same areas today. They are commonly seen in groups of 20-50 dolphins in the oceanic waters where they feed on flying fish and squid, and rarely venture on to the bank. However, along the western edges of Little and Great Bahama Banks this species can regularly be found on the bank during the daytime where they come to rest and socialise.

Rough-toothed dolphins (Steno bredanensis) are dark grey in colour with a long beak and prominent white lips. Their lower jaw and belly can sometimes be a pinkish colour. They reach just over 8 feet in length. They are an oceanic species and although appear to be rare in some parts of The Bahamas, can be regularly seen in the Tongue of the Ocean where they occur year round. Some individuals have been re-sighted in this area over the past ten years. They are typically found in groups of about 20 animals, but are sometimes in larger mixed-species aggregations of several hundred dolphins.

Risso’s dolphins (Grampus griseus) are large light grey dolphins that can reach over 13 feet in length, and have a relatively tall, dark dorsal fin. Adults are typically covered with overlapping white scars caused by the teeth of their con-specifics making them look quite battered. They have a rounded head, lacking a beak, but have a deep vertical crease down the center of the forehead. As they mature, their forehead becomes prominently white, and as such they are one of the easiest species to recognize at sea. Risso’s dolphins are commonly seen in oceanic waters in the northern Bahamas each winter and spring, primarily on the Atlantic side of the islands. It is unknown where these groups range the rest of the year, but some individuals have been seen off Abaco repeatedly over the years.

Technical details:
Photographs BMMRO
Designer Bee Design
Printer BDT International Security Printers
Process Stochastic Lithography
Perforation 14 per 2cms
Stamp size 28.45 x 42.58mm
Sheet Layout 20 (2 x 10)
Release Date 31 March 2016
Production Co-ordination Creative Direction (Worldwide) Ltd