20 Yards Off Scusset Beach
The presence of Great White Sharks off of Chatham has been national news all summer, but the sharks seem to have avoided Cape Cod Bay. That changed this week, but not in a bad way.
Multiple witnesses saw a dorsal fin at the Sagamore mouth of the Cape Cod Canal Wednesday morning. The fin was estimated to be 14-18 inches high. Descriptions of the beast lead this reporter to say that it was a Basking Shark.
Basking Sharks are generally harmless, but it's not a fun thing to suddenly have swim by you. They only eat plankton, but there aren't that many huge fish with dorsal fins that frequent the colder waters of Cape Cod Bay. You basically have 3-5 choices, and one of them (the Great White Shark) is a very bad booby prize.
The town of Orleans has this handy website that tells you how to differentiate between a Great White Shark and a Basking Shark. This is important stuff to know, because A) a Basking Shark is a cool thing to dive around, and it tolerates humans well, and B) a Great White Shark is a terrible thing to dive around, and it eats humans well. Both go from 10-20 feet long (bigger Basking Sharks can grow past 25 feet, and the record is a 40 footer caught in a herring net off the Bay Of Fundy), and both are frequently present in our waters.
The shark off Scusset Beach had a dorsal fin estimated to be 14-18 inches high. It flopped around to the sides, a sure sign of a Basking Shark. It also had a more rounded point (the Basking Shark dorsal fin looks like the end of a surfboard, while the Great White's fin has more of a sharp point), and was black in color. Only the fin was visible, taking away the easy way to distinguish between the two- the Basking Shark has a cavernous mouth that goes about a yard across, and the gill slits go right up to the top of the shark.
Basking Sharks like to show up off South Shore beaches and slowly cruise the water, gathering up the plankton. Chatham officials say that 99% of the shark sightings they get turn out to be Basking Sharks. The Scusset Beach shark was most likely one of these, as my eyewitness (John Kerrigan of Plymouth) provided "surfboard" to describe the fin without me suggesting it to him, and he also noted the size and floppy nature of the dorsal fin..
Great Whites do like colder water, and have been caught in Cape Cod Bay in places like Duxbury and Scituate. An 18 foot Great White was caught in the nets of a fisherman off Gurnet Point in 1938.
Two of the five fatal shark attacks in Southern New England history went down in Cape Cod Bay. An 1830 episode in Scituate saw a shark knock a fisherman out of a dory, while a similar thing happened in Boston Harbor in colonial times (est. 1730). I don't know if the Wampanoags lost anyone to the sharks. The other two attacks went down in Rhode Island (one was off Noyes Point in 1895, and the other involved a child swimming in from a fishing boat). The last fatal attack was in 1936, off Mattapoisett. The last non-fatal attack was off Truro earlier this summer.
Anyhow, make a point to check out that Chatham site. There are lots of useless things to know, but the difference between a harmless gentle giant and a brutal limo-sized killing machine isn't one of them.