a lot of shark meat is sold as 'scallops', if your scallops are all the same size & look like they're perfect circles, odds are they are shark masquerading as the more expensive scallop.
i sympathise with the diver, fish can be extraordinarily tough, my cutter was anchored in one of the little bays in the aleutians one sunday, one of the deckies was fishing off the stern & thought he'd snagged a big rock. turned out to be a 250+ lb. fluke (think BIG flounder). 4 hrs later he'd got it to the surface ( a relay of crewmen manned the pole, switching off as they tired ). after unsuccessful attempts to gaff it, the captain allowed a launch to be lowered, they tried from that, no luck. one of the cox's asked for his .44 mag from the armory & after a bit put 6 into the fish's head. finally it expired & they got it aboard. we ate fluke for days, breakfast, lunch & dinner.