NEW SHOREHAM, R.I. (WPRI) — The New Shoreham Harbors Department is urging everyone to remain vigilant after a series of shark sightings were reported Monday morning.

Harbormaster Kate McConville said in a Facebook post that the shark was spotted in and around Block Island’s Old Harbor basin.

Jon Dodd, the executive director of the Atlantic Shark Institute, confirmed that the shark spotted Monday was a rare shortfin mako. Mako sharks are an endangered species that can grow up to 13 feet long.

Anyone who sees a shark in the waters off Block Island should report it to the New Shoreham Harbors Department by calling (401) 466-3204.