They attach to rocks, jetties and piers and sometimes form dense beds on sandy flat substrates. They can be found from the low tide level to a depth of 10 metres, and they prefer sites with significant water movement. Blue mussels have a minor spawning period in June, followed by a second, extended spawning period from August to January. The fertilised eggs are planktonic, averaging 0.07mm in diameter and develop into unshelled larvae within a day. Larvae are free swimming and the planktonic stage can last from 2 weeks to several months, although most larvae settle 3-4 weeks after spawning.
Blue mussels are filter feeders, straining plankton from the water.
They are preyed on by crabs, starfish, leatherjackets, pufferfish and flat worms. Blue mussels are an important commercial fishery. There are only small sectors still harvesting wild mussels. Most mussels are aquacultured, grown using long line methods, with sprat collected via natural settlement. All farmed product is sold live and whole in the shell.