We have a pretty deep mussel aquaculture history here. Plump, grit/beard free and reasonably priced. An under-appreciated shellfish https://www.independent.com/news/2015/apr/02/flexing-muscles-over-mussels/
Not sure if the oil rig thing is still viable but it sure was/is interesting http://www.nytimes.com/1985/11/05/us/offshore-oil-rigs-prove-fertile-farm-for-mussels-on-the-coast.html