This photo is reportedly of "something" a fisherman killed in New Jersey.
A spokeswoman for New York's Department of Environmental Conservation, when asked for a positive ID, stated via email: "The photo doesn't allow counting of gill openings (seven per side for sea lamprey), but based on size alone, this does appear to be a sea lamprey."
According to the DEC, sea lampreys are eel-like jaw-less and boneless parasites, boasting mouths full of rasping teeth and a file-like tongue.
Whatever it is was not killed recently because if you notice the trees are green, so this must have happened back in the summer or something.
It's a weird looking thing that is for sure.
Thanks
~Tom~