A Chicago resident was fishing for salmon off Waukegan Harbor in Lake Michigan when he found a 4-foot-long caiman in the water.

The Chicago Tribune reported that David Castaneda was kayaking as he was fishing and initially thought the reptile, which is related to the alligator, was a dead salmon.

“I went closer to see if it was real,” Castaneda said. “I was just in shock. I wasn’t sure if it was a real alligator or a toy.”

>> Read more trending news

Castaneda called 911 and Waukegan Police Animal Control and staff at Larsen Marine Service, Inc. arrived to rescue the animal, which had tape over its mouth.

"It is not every day someone reports an alligator in Lake Michigan and the report is true," the city of Waukegan wrote on its Facebook page Monday. "This time the call was followed up with video of this four foot alligator slowly swimming in the Lake."

The Chicago Tribune reported that the caiman is being taken to the Wildlife Discovery Center in Lake Forest, Illinois. The center's curator, Rob Carmiachael, said the animal was "definitely on borrowed time."

“I would say it would be lucky if it lived another couple weeks,” Carmichael said. “Lake Michigan is only getting colder and colder each week.”

City of Waukegan spokesman David Motley said there will be an investigation to determine if the animal was abandoned, which is illegal.