I can't identify. The scope misses some offshore denizens who get tantalizingly close. There were a dozen last winter, more the year before. The pups were missing or grown last winter, and the yearlings allow passage within feet. A few were cut and bleeding, but survived.
Brown Shark are here in quantity.
I've come across badly mangled ones up to five feet, on the beach. I've had lots of good ones led by Jackie Sones from Wellfleet Bay Audubon . Monomoy's have been productive, and I had fun at my youthful favorite, Cuttyhunk. Peter Trul got me out last April 1 to view non existent duck with his radio transgression. I know what birds have been seen where and when by others, as well as my own sightings.