Speeding boats are killing our Port River dolphins

HALF of the dolphins killed in the Adelaide Dolphin Sanctuary in the past 13 years have died from being hit by boats - including baby Holly who was found dead last month. Environmentalists are now calling for a crack down on speeding drivers.

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HALF of the dolphins killed in the Adelaide Dolphin Sanctuary in the past 13 years have died from being hit by boats - with environmentalists calling for a crack down on speeding drivers.

A new report released today by the South Australian Museum found of the 35 known dolphin fatalities in the past 13 years, 17 were the result of blunt trauma - almost certainly from speeding boats.

An autopsy on bottlenose calf Holly – who, despite appearing healthy, was mysteriously found dead on January 2 – revealed the week old calf was killed by blunt trauma.

Baby Holly with her mother Ripple, before she was found dead last month. Picture: Marianna Boorman.

South Australian Museum senior researcher of mammals Dr Cath Kemper undertook the post-mortem on February 6.

“Our examination showed Holly was a healthy little dolphin with no apparent signs of disease,” Dr Kemper said.

“However, he had severe, deep haemorrhaging on the head and chest, which would have been caused by strong impact, possibly from a boat.”

Adelaide dolphin expert Mike Bossley said authorities needed to crack down on speeding drivers within the Adelaide Dolphin Sanctuary, particularly given three new calves have just been born in the river who “certainly don’t deserve” to be put at risk.

“If they are doing the speed limit they (dolphins) would be ok,” Dr Bossley said.

“The trouble is there are places that have got a speed limit of 10 knots (20km/h) that people just ignore and go flat out and there are plenty of places where there is no speed limit – that’s why there needs to be a review of the speed limits.”

He said the existing laws needed to be better policed by the authorities and river users need to be educated on how easy it is to injure a baby dolphin given how vulnerable they are when learning to swim.

One of the new calves born in the Port River and spotted yesterday for the first time. Picture: Sharon Sharp

He said there were only two ways a dolphin can die as a result of blunt trauma – being attacked by another dolphin, which is so rare there’s only been two cases documented worldwide, or being hit by a boat.

“Therefore, the only thing that could cause a blunt trauma injury is being a hit by a speeding boat – which suggests that half of the dolphins in our area have been killed by speeding boats.”

Dolphin conservationist Marianna Boorman said it was “heartbreaking” to know Holly was killed by a boat.

“Holly should still be swimming in the river and Ripple should still have her beautiful baby,” Ms Boorman said.

“There are currently three calves in the river – DPTI and the rangers need to be doing more to protect them so they don’t have to suffer the same loss as Ripple has.”

The 118sq km area covers the inner Port, Outer Harbor, the North Haven marina and stretches north to Port Gawler.

Boats are required to stay at least 300m away from dolphins.

The South Australian Museum has been monitoring Adelaide dolphin deaths for the past 30 years.

Lisien Loan from the Adelaide and Mount Lofty Ranges Natural Resources Management Board said the maximum penalty for interfering, harassing or intentionally harming a marine mammal is $100,000 fine or two years imprisonment.

“If a dolphin approaches your boat and you are travelling, you should maintain your current speed and direction,” Ms Loan said.

“Don’t make any sudden changes in direction, slow down or stop suddenly as this could injure the animal.”