NEW YORK - Multiple dolphins were spotted swimming in the murky waters of the East River on Tuesday, March 23, close to the shore in Brooklyn. The dolphins swam together near WNYC Transmitter Park in Greenpoint. A crowd gathered to watch the graceful marine mammals bobbing up and down in the water. Adam Figman and Cailin Anne posted videos on Twitter showing the dolphins exploring the area. Sightings of dolphins and even whales in the waters of New York City aren't unheard of but are a rare treat. In December, a humpback whale was seen swimming in the Hudson River near Midtown Manhattan. 'Tremendous surge' of whales in waters around New York City In 2017, a half-ton minke whale got stranded in shallow water off Orchard Beach in the Bronx. Despite the best efforts of police officers to try to coax the whale back into deeper water, marine biologists had to euthanize it. In 2013, a dolphin swam into the highly polluted Gowanus Canal in Brooklyn. The creature meandered around the Superfund site for some time and then died. Endangered right whales having a baby boom off East Coast Dolphins, porpoises, and whales face a number of potentially deadly threats in nature, including entanglements in fishing gear, collisions with vessels, and pollution. Marine mammals are protected under federal law. How can you help the efforts to protect and learn from these beautiful but endangered animals? Here are four ways, adapted from NOAA Fisheries: REPORT A WHALE SIGHTING – Virginia to Maine: 866-755-6622; Florida to North Carolina: 877-WHALE-HELP. STAY 500 YARDS AWAY – This applies to all aircraft, vessels, surfboards, and kayaks; NOAA Enforcement: 800-853-1964. REPORT MARINE LIFE IN DISTRESS – Report a sick, injured, entangled, stranded; or dead animal; never approach or try to save the animal yourself. BE INFORMED AND GET INVOLVED – Learn about conservation efforts, participate in public meetings, and volunteer with wildlife groups. With Storyful