Over The Horizon

Mussels Invade Pearl Harbour

Victoria University researchers Dr Jonathan Gardner and Smita Apte have used DNA detective work to track a stowaway mussel colony all the way from the Pacific coast of the United States to Pearl Harbour Hawai'i.

Gardner says the tenacious blue mussel, which stowed away on the USS Missouri, has defeated the best efforts of the US navy to prevent a biological invasion of Pearl Harbour.

"The USS Missouri was originally moored close to a mussel farm at Bremerton, Washington," says Gardner. "That's where the mussels first got on board."

"They then travelled with the USS Missouri to Astoria, Oregon, where the ship was moored for nine days in an attempt to prevent a biological invasion of Pearl Harbour. However, the mussels not only survived the mooring, but appear to have thrived during their two-week tow across the Pacific to Pearl Harbour."

"No sooner did the mussels reach Pearl Harbour than they started spawning. More very young mussels were then found on a submarine moored in Pearl Harbour."

"This shows how Pearl Harbour could be used by the mussels as a stepping stone for further invasions, and why the prevention of even temporary biological invasions is really important. Close monitoring of the situation within Pearl Harbour and the spread of the mussels outside is needed."

Gardner says the 70-80 mm blue mussels, which are eaten widely overseas, are extremely dominant. "They've got an ability to out-compete many native species."

DNA analysis has definitively identified the mussels as Mytilus galloprovincialis, a species which also occurs in Wellington Harbour. While it is not known whether the species was introduced to New Zealand or occurred here naturally, researchers believe it has invaded Japan, Hong Kong, South Africa and California within the last 150 years.