Mediterranean mussel

1. What is it?

Mediterranean mussels (Mytilus galloprovincialis) are medium-sized, widely distributed mussels that were introduced into South African shores in the late 1970s. Since then, this invasive species has spread rapidly along the coastline dominating nearly 2000 kilometers of our shoreline. Within South Africa, the blue mussel stocks are said to be under-fished, at a rate which is likely to maintain or increase the stock to healthy levels.

2. How was it caught or farmed?

Mediterranean mussels are collected by hand off rocks and other substrates within the intertidal zone. Hand collection of blue mussels is a highly selective method with little or no bycatch. There should be little damage to the environment although some damage is possible from dragging sacks or baskets over the bottom.

Mediterranean mussels are farmed on ropes suspended in the water column from floating rafts in sheltered bays in the sea. As mussels are filter feeders no feed is required and damage to the environment is minor and generally limited to the immediate area (waste discharge that has settled on the floor). Mussels actually enhance water quality by clarifying water and reducing concentrations of organic matter and nutrients in the water column.

3. Where is it from?

Mediterranean mussels are found all along South Africa's coastline. Management is in the form of permits and daily bag limits (30 pp/pd). Only recreational and subsistence fishers are allowed to hand collect blue mussels.

Mediterranean mussels are farmed largely around Saldanha Bay. Management is in the form of strict environmental assessments and permit regulations. Measure need to be put in place to minimize further introduction as wild populations have already been established in Port Elizabeth after blue mussels escaped from areas designated for aquaculture purposes.