Asian green mussels are not native to Florida, but have become a permanent resident in some parts of the state.
The Asian green mussel (Perna viridis) is an invasive species, meaning it is not native to Florida waters. The green mussel is originally from the Indian and Pacific oceans but was introduced into the Gulf of Mexico in the 1990s, presumably as larvae trapped in cargo and tanker ballast water, which large ships take in to increase stability during transit and release upon arrival. Green mussels were first observed in Tampa Bay in 1999. They outcompeted local species for space and were not initially eaten by local predators, which allowed the mussels to rapidly increase in numbers and spread throughout the waters surrounding the Florida peninsula. Green mussels spread to Charlotte Harbor by 2000, Ten Thousand Islands and Mosquito Lagoon by 2002, Jacksonville and Savannah, Ga. by 2003, and have been reported as far north as Charleston, SC. The FWC is currently monitoring the spread of juvenile green mussels at sites around the Gulf of Mexico.
Green mussel larvae settle on hard, submerged surfaces and can form large masses that can clog intake pipes and restrict water flow to power plants and hatcheries. These masses can also affect floating structures, sinking buoys and increasing drag on boat hulls. Since they can grow so fast and have fewer predators, green mussels thrive in Florida waters and settle onto substrates (surfaces) that native mussels or oysters would normally use. With no space to attach, local populations of native species may collapse, and as a result the local crab and fish populations may also decline if they rely on those mussels for food.
The green mussel usually has a bright emerald green shell that can exceed six inches (160 millimeters). It is a prized food in China, the Philippines and Malaysia. But shellfish harvesting in a large portion of Tampa Bay is prohibited, and most Tampa Bay shellfish, including mussels, are not safe to eat. For shellfish harvesting area information, including the current status of Tampa Bay, please visit the Florida Department of Agriculture and Consumer Services website.
To help prevent the spread of these mussels, boaters can follow these suggestions:
- Inspect any boat that has been in Tampa Bay unprotected (without fresh bottom paint); remove and dispose of mussels if you see them.
- Prior to transporting boats to other water bodies, drain the bilge at an appropriate disposal station or, if no oil is present in the bilge water, into Tampa Bay.
- Spread the word; make others aware of the problem nonnative species can cause.
Green mussels are edible, but consumers should follow the Florida Department of Health seafood safety guidelines and only consume shellfish collected from areas open to harvesting, which can be found on Florida Department of Agriculture and Consumer Services website.