Brailing is a form of early commercial pearl and mussel harvesting (in the 1930s, 40s and 50s).
When brailing, you extend hooks across a bar and pull the bar through the river. The mussels close on the hooks. Why? When a mussel feels the hook on its open shell, it thinks one of two things.. that it is food or a predator. Its response is to clamp down onto the hook.
Brailing boats travel down the river with the brails on the upstream side of the boat. Most mussel catchers know when the brail is full by the weight. The loaded brail is then pulled on the boat and an empty one is loaded in its place. That way, while men are picking mussels off the hooks, they can continue to catch more. Brailing is effective when there are a lot of mussel beds, otherwise it is tough to catch many mussels.
Today, brailing is a lot less effective and is pretty much obsolete. Check out our brailing video...