Dolphin encounters in the Maldives Part – 2

The Maldives is a tourist hot spot for dolphin cruises. These majestic animals are found commonly around Gili Lankanfushi and never disappoint with their impressive aerial displays and playful attitude.

The Maldives is a dream destination for wildlife seekers and ocean adventurers. The ocean temperature averages between 27 – 31°C, contains plentiful fish and has incredible visibility. This makes it an ideal location for cetaceans: whales, dolphins and porpoises. They are aptly named as the word cetacean means huge fish.

Spinner Dolphins:

Spinner dolphins are a common species of dolphins seen in the Maldives and worldwide. They are easily identified due to their tricolor pattern, the upper side is dark grey, the middle a light grey and the underside white. They have a defined dark line from the eye to the flipper and an elongated nose. They get their name due to their unique jumping behaviour, they are the only species of cetacean to spin laterally in the air. The maximum number of spins recorded is seven. These spinning displays can vary, these variations are thought to be caused by habitat differences.

Spinner dolphins are usually found in coastal environments generally associated with island chains or atolls. Spinner dolphins have a high re-sighting rate which indicates high site fidelity. During the day they use bay areas to rest and socialise, at night they venture offshore to hunt. These resting bays are generally in close proximity to feeding grounds, have a flat and sandy bottom with a depth around 20m. These features allow the dolphins to use only vision (instead of echolocation) to keep a look out for predators. If visibility is poor the dolphins are unlikely to rest as they are vulnerable to predation.

Reproduction in spinner dolphins varies greatly between sub-species. Their calving period is year round with a gestation time of 10.5 months, after birth the calf will nurse for two years. The period between calves is three years. Females reach sexual maturity earlier than males (seven for female and seven to ten for males).

Spinner dolphins have predictable daily patterns but there social structure is variable. Group size varies with habitat, with some open ocean populations traveling in groups numbering thousands. Group size could be dependent on the size of the sandy bay bottom and activity, for example resting group size is smaller than hunting groups. Dolphins living in remote reefs and atolls have higher affinity to each other whereas coastal population are more changeable. In coastal environments individual groups rest separately during the day and can come together at night to hunt. These dolphins typically hunt prey that live in deeper water but migrate vertically at night following the plankton. Feeding occurs at depths between 200 – 400m and includes fish, shrimp and squid. The size of the prey is small (five – 15cm) with males preferring lantern fish and females cuttlefish. Spinner dolphins along with bottlenose dolphins are vulnerable to a variety of human activities and developments.

Potential Threats:

The majority of bottlenose and spinner dolphins in the Maldives reside in coastal environments which makes them highly susceptible to human activities. Coastal habitats are becoming degraded and as such management of coastal environments is critical for dolphin survival. Both species of dolphin are particularly vulnerable to human activities including dolphin watching, swimming with dolphins, pollutants including acoustic and chemical pollution, gillnets, by-catch, hunting, habitat degradation, boat traffic, sea planes, climate change, purse seines and trawling fisheries.

As awareness about the threats to the planet grows there is a shift from activities that degrade wild animal populations to activities that educate and raise awareness. The number of participants for dolphin watching activities is growing and highly profitable. Dolphin watching has many positives; less invasive than swimming with dolphins, reduced desire from aquariums, alternative employment, reduced hunting and by-catch. Unfortunately some dolphin watching activities have little or no regulations and can be conducted in a manner that is negative for the dolphins. These activities can alter feeding, resting and reproductive behaviours. Stressed behaviour can be exhibited as changes in swimming speed and direction, changes in communication, respiration rate and aerial behaviours.

It has been observed that cetaceans avoid areas with heavy boat traffic and it is thought that disturbances to dolphins could lead to increased injury rate, unsuccessful reproduction, increases stress and damages survival probability. Prolonged disturbance may lead to permanent relocation of dolphin populations. A common misconception people have with dolphins is that they can leave if they aren’t happy, dolphins can find themselves too stressed, confused and blocked in by boats to leave. Additionally, many dolphins are reliant on coastal environments, moving away from the coast can lead to diminished survival chances. As more research is conducted it has become apparent that dolphin watching can be executed in a sustainable way.

PADI’s guest blogger Emma Bell introduces herself:

I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.

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