There have been quite a few caught in that general area over the years, its common knowledge. The mussel beds would be one reason they come in there at a guess.
Some of the biggest have been caught close to the river mouths though, and there no shellfish beds there.
I think these big solitary fish tend to roam up and down the beach eating crabs and whatever else they can find, and if you happen to have a bait in the water as they come past you're this years lucky angler