Quarantine protocols help contain Cockburn Sound marine pest

The Department of Primary Industries and Regional Development (DPIRD) is issuing a Quarantine Area Notice to prevent the spread of carpet sea squirt (Didemnum vexillum) detected at a Henderson marine facility.

Carpet sea squirt is a highly invasive marine invertebrate that can overgrow and smother shellfish, sponges and algae, and cause fouling of vessels, marine or aquaculture infrastructure.

DPIRD incident manager Peter Adams said carpet sea squirt was detected through a long-running targeted surveillance program for marine pests operating at WA ports which offered a vital early warning system.

The department extended its surveillance for carpet sea squirt after it was identified on wharf infrastructure at the Australian Marine Complex at Henderson in January 2023.

Expert divers are conducting underwater surveys of marine habitats and infrastructure in surrounding waters to determine if it has spread further.

DPIRD has also been supporting the Australian Government Department of Agriculture, Fisheries and Forestry and the Department of Defence to respond to a previous detection at Garden Island in 2021.

Dr Adams said the Quarantine Area covered the waters adjacent to the Australian Marine Complex (AMC) at Henderson South, and encompassed by seawalls to the north and west, and extending 250 metres down the coastline south of the AMC.

“Since the detection, we’ve been working closely with local operators within the Quarantine Area and Fremantle Ports to manage commercial vessel movements and procedures to minimise the risk of spread,” he said.

“The Quarantine notice further strengthens the requirements for biofouling inspections and treatments for vessels that regularly operate in the Quarantine Area or have been in the Quarantine Area for a period of six days or more.

“There are no restrictions or requirements for vessels berthed for less than six days. The Quarantine Area covers waters that are typically restricted access waters, and recreational vessels should avoid the area.”

Dr Adams said boat users could help stop the spread of any marine pests by keeping their boats, trailers and equipment clean and free of marine fouling.

“We recommend using soapy water to clean boats and trailers, fishing rods and other equipment on land, ensuring marine life does not re-enter the water when cleaning, and allow them to dry completely before using them at another location.”

“The public can also report any unusual marine species attached to vessels or submerged infrastructure to www.marinepests.gov.au/report