Maui's dolphins: threats
Their underwater home is a dangerous place
The main threats to Maui's dolphins today are:Why are gill nets a serious threat?
The most significant threat to Maui's dolphins is from gill net fishing. Dolphins do not seem able to detect the fine nylon nets and swim into them.
They cannot swim backwards so are unable to free themselves from the net. Unable to reach the surface to breathe, they drown within a couple of minutes.
WWF's campaign for a ban on gill netting was partially successful; it is now banned to 7.4 kilometres (4 nautical miles) off the coast in the Maui's dolphin range.
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Trawling a threat to the dolphin and their habitat
Fishing trawlers can be dangerous as they capture almost everything in their path. The interaction between trawlers and Maui's dolphin is currently being studied to see how trawling in the region and the Maui's range overlap and what further protection is required.
Trawling is currently only banned to 1.85 kilometres (1 nautical mile) off the coast. It is known that dolphins can drown when they get entangled in the trawl nets being pulled behind the boats.
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Pollution the silent killer
Maui's inhabit shallow coastal waters and are vulnerable to marine pollution. Chemicals from industrial waste, storm water and agricultural runoff like PCBs, DDT, dioxins and metals have been found in Maui's dolphins. These pollutants bio-accumulate, which means they increase in potency as they move up the food chain.
Maui's dolphins are near the top of their food chain and these pollutants can be passed on to young dolphins through their mother's milk. High levels of exposure can cause loss of fertility and compromise immune systems in marine mammals.
Another form of pollution which threatens Maui's dolphins is solid rubbish such as plastic shopping bags which can be mistaken for jellyfish or squid and eaten, killing the dolphin. In New Zealand alone, 22 million plastic bags are used every week.
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One boat strike is all it takes
The Maui's dolphin lives in an area that sees plenty of summer tourists and regular fishing locals, year round. Boat strikes are sometimes accidental, but other times people are curious and go closer than the advised 300 metre distance.
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Related links:
- WWF Story - A whale of a tragedy
- Threatened species: Cetaceans
- News Articles from www.mauisdolphin.org.nz
