There are bull shark occasionally in the Delaware river. One was caught in a net in 1908 basically across the river from where the Philly Airport is today.

Bull sharks are indeed present in the Delaware River, particularly during the warmer summer months. Unlike most shark species, bull sharks have a unique physiological ability to tolerate freshwater, allowing them to swim hundreds of miles inland. In 2026, sightings and scientific tracking continue to confirm their presence as far north as the Philadelphia area, though they are most common in the brackish waters of the Delaware Bay. While their presence often sparks concern among swimmers and boaters, unprovoked attacks in the river remain exceptionally rare. These sharks are primarily following prey, such as Atlantic menhaden or striped bass, into the river system. Biologists note that as water temperatures rise globally, the window of time these sharks spend in northern estuaries like the Delaware has gradually widened. Despite their reputation, they generally avoid human interaction, sticking to the deeper, murky channels of the river.