Oceanographers were able to collaborate with beachcombers in the western US (and eventually as far away as the UK) to validate their models of how the currents would move the ducks.
They had places they’d go after bad weather, knowing that’s where wrecks ended up.
Sometimes local traditon encuraged potential salvage, by setting up false lights.
edit:
https://en.wikipedia.org/wiki/Wrecking_(shipwreck)
but wikipedia actually says, this might be a urban legend, as there is no clear evidence this ever happened
https://www.japantimes.co.jp/culture/1999/06/08/books/the-da...
http://www.bbc.com/travel/story/20190908-a-shipwreck-worth-b...
In the UK there is some dispute about 'finders keepers' in any case, there was a case last year where a couple of guys got jail time for stealing a hoard
https://www.bbc.com/news/uk-england-hereford-worcester-50516...