NEW YORK—A marine biologist says an aging dolphin that was stranded in a polluted New York canal and died there was ill and might not have survived anywhere.

Kim Durham of the Riverhead Foundation for Marine Research and Preservation on Long Island conducted a post-mortem exam of the wayward mammal. She says the dolphin suffered from a series of chronic conditions: stomach ulcers, kidney stones and parasites.

Durham says the 7-foot male weighing about 340 pounds struggled before it died on Friday in Brooklyn's Gowanus (guh-WAH'-nuhs) Canal, splashing around and shaking black gunk from its snout. The canal is a Superfund site, where for years factories and fuel refineries operated.

The dolphin likely entered the canal from the Atlantic Ocean and got pinned at low tide.