Reusable bins of shell carried out for use on the Hampton River in Virginia. This is a much better use of plastic than filling the river with plastic mesh bags stuffed with oysters.
Actually, from my observations, at several sites, oyster bags they tend to break over time. Rebar and other ways have been used to strap them down. But one of the most important points to note is that as an oyster gets larger its sharp edges end up cutting the mesh bag and the shell is then loose. We should be keeping plastics out of the water, and marsh.
So, why not start with loose shell?
Don’t forget you may need some relief to get your oysters started, or at least an area with less silty water allowing a surface for spat to settle. Reef Balls have been proven very effective at accomplishing what you need for shellfish restoration, not just oysters but EFH and breakwaters.
Oyster Bags at Morris Landing NC 2016