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State of the Coast: KZN
State of the Coast: KZN

State of the Coast: KwaZulu-Natal Chapter 1: Introduction & Background Chapter 2: Overarching Drivers Chapter 3: Climate Variability
Chapter 4: Coastal Environment Chapter 5: Estuarine Environment Chapter 6: Marine Environment Chapter 7: Human Environment Chapter 8: Economic Environment
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The Profile of the KZN Coast

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Coastal risk and vulnerability

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09 Oct 2017

Why hurricane season is good for dolphins

Ishani Chetty (Traveller24)

“Dolphins are one of the most friendliest and clever mammals of the ocean and most of us cannot resist to capture a photo of them or get up-close to them.“

Scientists have estimated a ‘baby boom’ of this lovable species – as a silver lining to the recent devastating hurricanes that hit Atlantic shores – but this may not a make a difference to the species overall if conservation efforts do not succeed.

Baby Boom

Marine scientists predict that due to the recent hurricanes that swept through the oceans, there will be an increase in species of dolphins, as was seen after hurricane Katrina. Scientific America supports this due to the evidence from the previous hurricane along the American coast.

Biologist Lance Miller came across the vast increase in baby dolphins along the Gulf of Mexico in 2005 and 2006, conducting research to conclude that hurricane Katrina had caused the sharp incline in species.

Miller indicates that there are two reasons for the increase – firstly that when female dolphins lose their offspring they are ready to have a child in the following season, while the second reason is linked to human fishing patterns.

There have been many theories as to why this would occur but the main reasons appears to be the decrease of the fishing industry – and as a result of this there is more food for these aquatic creatures. Also, an increased source of food in the ocean ensures that pregnant females are more likely to give birth to healthy babies.

Even though the effects of hurricane Katrina increased the population of dolphins, they are still under direct threat from a wide range of factors. This baby boom may only see a slight increase in the species as a result of increased poaching and by-catching.

Under threat

Climate change

According to the Whale and Dolphin Conservation (WDC), climate change is a direct threat to the population of dolphins, which are known to be shallow water creatures.

Due to the rising level waters and increase in water temperatures it is unclear whether these mammals will be able to adapt to their new oceanic conditions. Climate change will decrease the habitat that is available for these mammals and this will cause a series of negative effects on their migration, reproductive success, distribution, and prey species increases.

By-catching

A prominent threat to the species is by-catching – this occurs when fisherman throw out their nets into the ocean and in the process entangle and trap dolphins.

In many instances these dolphins are not set free and can die from the entanglement according to the WDC. The WDC is working together with fisherman to modify their methods and help alleviate this threat.

Dolphins need a constant flow of oxygen and can suffocate under water hence they peak out of the ocean waters to get fresh air through their blow hole. Being entangled within the net can stop the flow of oxygen to these mammals.

Poaching

Dolphins are poached in parts of the world and their body parts are used for medicinal purposes or food – this was highlighted with the release of the documentary ‘The Cove’. Although poaching and hunting is illegal in many parts of the world, individuals are continuing to kill these mammals.

Understanding dolphins

In South Africa there are three common species of dolphins; the common bottlenose dolphin, the Indo-pacific humpbacked dolphin and the long-beaked bottlenose dolphin. Each has its own quirky characteristics but they all share a common trait of vocal communication.

Various studies conclude that these mammals communicate with one another through the mechanism of sound. They let out a squeaking sound in order to relay a ‘hey’ to their friend or even a ‘I am not happy to see you’.

According to the University of Pretoria, studies are still being conducted to understand the difference in tone and the messages being communicated. The study concludes that there are differences in the sounds communicated, based on the type of dolphin – and on the level of echoes that were monitored.

This type of dolphin is known as the common bottlenose dolphin and is spotted across South Africa. Surfers and swimmers usually encounter these warm animals in the ocean.

 

Online Article