Commercial shipping and the water ballast systems aboard large ships have long been identified as responsible for the spread of marine pests that can wreak havoc on our marine ecosystems. As home to the port of Melbourne – Australia’s busiest container port – and to the Port of Geelong, it’s therefore no surprise that Port Phillip Bay is riddled with marine pests.
The most common of these is the highly invasive and predatory Northern Pacific Seastar, Asterias amurensis. Parks Victoria’s State-wide Leader – Marine and Coasts Mark Rodrigue describes the seastars as ‘voracious’. ‘They will eat essentially anything that’s not bolted down,’ say’s Mark. And, horrifyingly, at their peak there was a greater mass of the seastars than fish in the bay. Other invasive species, such as Wakame, Undaria pinnatifida, are also thriving and competing with native algae for habitat.
Wakame growing on a boat in Port Phillip Bay.
Roellen Gillmore, Marine Communications Officer for Parks Victoria and a keen sailor, only recently realised the extent of the problem, and what she describes an ‘opportunity to contain the marine pests’. ‘As sailors, we just aren’t aware,’ says Roe. ‘We don’t really think about what’s going on below, but there’s a whole new world under our keels.’
She explains that Wakame, Northern Pacific Seastars and their microscopic offspring can easily become attached to boats and marine equipment and spread to new waterways. While Roe jokes that she now has an environmental incentive for washing her boat down, she’s deadly serious when she says that she wouldn’t want to be the person who causes the spread. ‘Once they become established, it’s nearly impossible to get rid of them,’ say’s Roe. ‘The best management option is to prevent the spread, and it’s the human factor that we all can control.’
A Northern Pacific Seastar found by Marine Ranger Chris Hayward in Tidal River in late 2017.
Thankfully these marine pests have, to date, been largely contained to Port Phillip. While some natural dispersal is unavoidable as it occurs with the tidal movements, in Victoria, New Zealand, and across the world, there is an increasing recognition that there is a danger of all vessels, including travelling boaties, unintentionally spreading pests. Past outbreaks of pests at Apollo Bay and Wilsons Promontory indicate we’re only just keeping a grip on the issue.
So while there’s already plenty on our minds as we prepare to set off through Port Phillip Heads or travel to another waterway or coastline, we also need to ensure we’re not taking dangerous stowaways with us. Here are the key things we need to do to avoid spreading marine pests;
1. Use fresh water to wash all equipment. Everything from kayaks, fishing equipment, diving gear, fenders, and anchor chain.
2. Ensure that all equipment, including sails and lines are dried as microscopic offspring can survive for long periods in the damp.
3. Yacht owners should ensure that their antifoul is kept up to date and that hulls are checked for attached marine life.
4. Sewage and bilge water should be emptied at an approved facility, and any saltwater systems on board should be flushed out or treated regularly.
5. Keep your eyes out for these pests beyond Port Phillip Bay and report sightings to email@example.com.
Parks Victoria divers removing Wakame at Popes Eye, Port Phillip Bay.
While any opinions expressed by the author are absolutely her own, this article has been produced in collaboration with Parks Victoria. For more information on how boaties can prevent the spread of marine pests and to report any sightings, please see Parks Victoria’s website.