NEW YORK (AP) Andrew Orkin was taking a break from his evening jog to sit by Prospect Park Lake when he turned around and was startled to see a tangle of wriggling snakes.

And quite a big pile fully alive, said Orkin, a music composer who lives near the Brooklyn park.

They turned out to be eels that had escaped from one of two large plastic bags that split open as a man dragged them to the shoreline. After dumping the eels in the lake, the man walked away, explaining to bystanders that I just want to save lives.

The illegal release late last month became a curiosity on social media, but the dumping of exotic animals in urban parks isnt new. In cities across the country, nonnative birds, turtles, fish and lizards have settled into, and often disturbed, local ecosystems.

New Yorkers free thousands of non-native animals every year, many of them abandoned pets that quickly die. But others can survive, reproduce and end up causing lasting harm.

People like animals and they sometimes think theyre doing a good thing by letting them go, said Jason Munshi-South, urban ecologist at Fordham University. Most will die. Some will become a problem, and then theres no going back.

New York state and city officials say its too soon to know how the eels in Prospect Park might affect local species. But based on photos taken by bystanders, officials identified them as swamp eels native to Southeast Asia like those that have been found in at least eight states.