Invasive marine pest found in Fiordland

A single specimen of the introduced Japanese kelp Undaria pinnatifida has been found in the remote Sunday Cove, Breaksea Sound in Fiordland. This is the first discovery of an introduced marine pest in Fiordland.

Undaria is an unwanted organism under the Biosecurity Act and is also designated as a pest in Environment Southland’s Regional Pest Management Strategy. It is a fast-growing seaweed that can spread rapidly, displacing native species, and having major impacts on marine ecosystems. It was accidentally introduced to New Zealand waters in the mid-1980s and has become widespread throughout much of the country’s east coast ports and harbours.

The solitary mature plant was found on a barge during a joint-agency surveillance and compliance checking exercise in the Fiords involving staff from the Ministry of Fisheries, Environment Southland, Department of Conservation and MAF Biosecurity New Zealand.

Environment Southland Biosecurity Manager, Richard Bowman says the Fiordland specimen was growing on a rope tethering the barge to the shoreline.

“The plant was a mature specimen with its reproductive parts well developed. It was completely removed from the rope and sent away for confirmed identification. We have now received that positive ID,” Mr Bowman says.

Malcolm Lawson, Chair of the Fiordland Marine Guardians (a group of community representatives who advise central and local government on managing the Fiordland marine environment), says the find is hugely disappointing.

“Fiordland has a special and unique marine environment and a lot of effort by various agencies has gone into protecting the area from the introduction of marine pest species.”

Mr Lawson says, however, that everyone involved is heartened that only a single plant was found, and a search of the area, including the barge itself and an adjacent permanently moored vessel, did not reveal any further plants.

“This find reinforces the need for everyone entering the Fiordland Marine Area to take care not to introduce or spread marine pests. It is vital that that the owners and operators of boats entering Fiordland ensure their vessel hulls are clean and thoroughly antifouled, and that all marine equipment such as ropes, mooring lines, pots, buoys, fishing and dive gear are clean and dry.”

Environment Southland, MAF Biosecurity New Zealand and the Department of Conservation are now considering investigation and potential management options.