Petra Stock
Large ships are frequently sailing through Australia’s marine parks, risking collisions with whales and whale sharks and polluting protected environments with noise and chemicals.
Around 18 per cent of marine parks are exposed to high shipping traffic involving more than 365 vessels each year, according to research in Marine & Freshwater Research.
Half of all marine parks are exposed to what the report describes as “moderate rates” of shipping exposure — more than 90 vessels per year.
Australia has 3,340 identified marine parks, reserves and protected zones, including UNESCO-listed world heritage areas such as the Great Barrier Reef and Ningaloo Coast.
These protected zones are a mix of both national and state identified areas and are designed to conserve underwater species and habitats by limiting disturbance from human activities.
But lead author Dr Vincent Raolt, an ecologist from the University of Newcastle, says when it comes to shipping, “there’s actually very little that says you can’t drive a ship through different marine parks.”
Most of Australia’s east coast and parts of the western coast are exposed to high rates of shipping.
Large ships are a problem for marine environments because they can collide with whales and whale sharks and pollute marine environments with noise and chemicals.
The study overlaid marine protected areas, with data on shipping routes from the Australian Maritime Safety Authority from 2018 to 2021, and satellite-tag reports from 52 whale sharks, 18 pygmy blue and 137 humpback whales.
The results show tagged whales and whale sharks are often exposed to at least moderate rates of shipping activity.
Ships pose a risk directly to marine giants like whales and whale sharks through collisions, and indirectly through underwater noise.
Raolt says collisions with whales and whale sharks are underreported, in part because many animals sink when struck, and are unlikely to be noticed by ships when they occur.
“It’s quite morbid, because usually the only time the captains recognise that they’ve hit a whale is when they pull up the port and there’s literally a whale draped across the bow,” he says.
An earlier study of whale sharks found almost one in five had major scars or injuries, thought to be mostly caused by encounters with ships and propellors.
The underwater noise created by ships is significant. At normal cruising, propellors produce low frequency noise – which can be as high 190 decibels the paper states, much louder than a jet engine – able to travel further through water than air.
Raolt says, “those low frequency sounds are the ones that travel the furthest. And they’re the ones that whales, for example, used to communicate over large distances. So you can imagine if there’s all this background noise of ships, basically whales have to shout to communicate.”
Read more: Boats bug whales
It’s not just whales affected by the noise pollution. Many marine animals – even oysters – are sensitive to underwater sounds. Modifying the ocean soundscape, with shipping noise, might be degrading it, says Raolt.
Then there’s the chemical pollution from shipping which can include oil spills and the leaching of copper used to protect ships from biofouling.
Raolt hopes the study – a collaborative effort by six universities, government agencies and ECOCEAN Inc – will draw attention to the environmental impacts of shipping in marine parks.