"wrecking" was the practice of scavenging from shipwrecks, technically a crime from the 17th century onwards, but among the people it was a long standing folk tradition that anything which washes up on the beach is fair game.
It would have been so much fun though, imagine it - you get pulled out of bed in the middle of the night, down to the beach as the wind whips and the waves crash, seeing by flaming torch light…it could literally be anything that washes up, so much trade is done by sea - could be gold, could be weapons, silk, whisky, food, anything..a carnival atmosphere as everyone splashes around helping themselves to whatever fate has brought them.
It was one of those things that was illegal for decades before anyone even considered it to be wrong, like poaching and distilling. It’s a pure property crime, expecting people to respect someone’s property even after it has been dispersed by an act of god in such a way that they’ll never get it back. It’s completely illogical not to take the stuff, unless you are attempting to invest private property with some kind of sacred force field which people respect in a religious manner.