You’re standing on the banks of the Delaware, maybe near Penn’s Landing or further up toward the Delaware Water Gap, and the water looks... murky. Dark. A little bit mysterious. It’s a natural thought to have, especially when the summer heat hits and you're thinking about taking a dip. Are there sharks in the Delaware River? The short answer is yes. But honestly, it’s not the "Jaws" scenario you’re probably picturing in your head.
People tend to think of rivers as safe zones, these freshwater barriers where the terrors of the deep can't reach. That’s a mistake. Nature doesn’t really care about our geographic labels. While you won't find a Great White chasing a kayak near the Ben Franklin Bridge, the Delaware River is a massive, tidal waterway that acts as a highway for all sorts of marine life.
👉 See also: How Far is Jackson MS From New Orleans: What Most People Get Wrong
The Bull Shark: The Only One That Matters
If we’re talking about real, toothy residents, we’re talking about the Bull shark (Carcharhinus leucas). These guys are the biological anomalies of the shark world. Most sharks would literally die if they swam into freshwater because their cells would explode from the osmotic pressure. Bull sharks are different. They have specialized kidneys and glands that allow them to recycle salts, meaning they can thrive in the salty Atlantic, the brackish Delaware Bay, and the almost entirely fresh water of the river itself.
They aren't just "passing through" either.
Scientists have tracked Bull sharks hundreds of miles up rivers globally. In the Delaware, they’ve been documented well past the bay. They like shallow, warm water. They like where the river gets a bit silted.
It's a nursery.
Female Bull sharks often head into estuaries and lower river reaches to give birth. Why? Because it’s safer for the pups. Large oceanic predators won't follow them there. So, while you might not be swimming with an eleven-foot monster, the "young of the year" are absolutely present in the Delaware during the warmer months.
Where the Sightings Usually Happen
The Delaware River is long. It starts up in the Catskills and dumps out into the Atlantic. You aren't going to see a shark in the shallow, rocky rapids of the Upper Delaware near Hancock, New York. That’s trout territory.
The action is south.
Most sightings and catches occur in the Delaware Bay and the lower tidal river, roughly from the mouth of the bay up toward the C&D Canal and sometimes as far north as the waters off Wilmington or Chester. The water here is brackish—a mix of salt and fresh—which is the "sweet spot" for these animals.
In 2021, a viral video claimed to show a shark near the Burlington-Bristol Bridge. People freaked out. Was it a shark? Maybe. Could have been a large sturgeon or even a wayward Atlantic stinger. But the fact that people believed it shows how much we know these waters are connected to the ocean.
Sandbar Sharks and Smooth Dogfish
While the Bull shark is the one that gets the headlines because of its reputation, it isn't the most common. If you’re fishing the lower Delaware, you’re much more likely to hook a Sandbar shark or a Smooth Dogfish (often called "sand sharks" by locals).
The Sandbar shark is actually one of the most abundant large sharks on the Atlantic coast. They love the Delaware Bay. In fact, the Delaware Bay is one of the most critical nursery grounds for Sandbar sharks in the entire Western North Atlantic.
They stay in the saltier parts of the bay, but they’re still technically "in the river" system.
The Smooth Dogfish is even more common. They don't have the "scary" teeth—they have blunt plates for crushing crabs and mollusks. If you've ever gone "sharking" in Cape May or Lewes, you've probably caught a dozen of these. They’re harmless to humans, but they are, by definition, sharks.
The Sturgeon Confusion
We have to talk about the Atlantic Sturgeon.
These things are dinosaurs. Literally. They’ve been around for millions of years, and the Delaware River is home to a small, endangered population of them. They can grow to be 14 feet long and weigh over 800 pounds.
When a sturgeon breaches—which they do, jumping clear out of the water for reasons scientists still argue about—it looks like a monster. They have bony plates called scutes along their sides that can look like fins from a distance. A lot of "shark sightings" in the Delaware River, especially further north toward Philadelphia and Trenton, are actually just people seeing a massive, ancient sturgeon doing its thing.
It’s easy to misidentify something when you’re looking through 50 feet of river haze and splashes.
Why You Shouldn't Be Scared to Swim
Okay, so we established that sharks are in the Delaware River. Does that mean you’re going to get bitten?
Statistically, no.
✨ Don't miss: Weather for Estacada Oregon: What Most People Get Wrong
There has never been a recorded, unprovoked shark attack in the Delaware River. Not one. The water is generally too murky for sharks to see humans as anything interesting, and we aren't their natural prey. Bull sharks are opportunistic, but they’re looking for fish like menhaden (bunker), shad, and eels.
Honestly, you should be more worried about the current. The Delaware has wicked undertows and tidal pulls that drown people every single year. The bacteria levels after a heavy rain are also a much more immediate threat to your health than a shark fin.
The Impact of Water Quality
Back in the 1950s and 60s, the Delaware River near Philly was basically a dead zone. The dissolved oxygen levels were so low that fish couldn't breathe. If fish can't breathe, sharks don't come around. There’s no buffet.
But thanks to the Clean Water Act and decades of restoration work, the river is cleaner than it’s been in a century. The shad runs are returning. The striped bass are thriving.
When the prey comes back, the predators follow.
Seeing or knowing there are sharks in the Delaware is actually a good sign. It’s a sign of a functioning ecosystem. A river that can support a top-tier predator like a Bull shark is a river that is alive.
Real World Incidents
In August of 2024, a juvenile shark was found washed up on the shores of the river in Northeast Philadelphia. It caused a stir, but experts from the New Jersey State Aquarium and local biologists noted that it’s not entirely "unnatural," even if it’s rare for them to end up that far north and then expire.
Most of the time, if a shark is up that high, it’s a youngster that got turned around or a sick individual. But the "nursery" aspect of the Delaware Bay cannot be overstated. Researchers like those from the University of Delaware’s ORB Lab (Ocean Exploration, Remote Sensing, and Biogeography) spend a lot of time tagging sharks in these waters. Their data shows a consistent, seasonal migration.
They come in when the water warms up in June. They leave when it cools down in September.
📖 Related: Finding a New York to Arkansas Flight That Doesn't Break the Bank
What to Do if You Encounter One
If you’re fishing and you hook a shark in the Delaware, don't play hero.
- Keep it in the water. Most of the sharks found here, like the Sandbar shark, are protected. It is illegal to take them out of the water in many jurisdictions.
- Cut the line. If you can’t safely remove the hook with long-nose pliers, just cut the leader as close as possible. The hook will eventually rust out or be shed.
- Don't bleed your catch. If you're keeping perch or stripers, don't string them over the side of the boat in the lower river/bay. That’s a dinner bell.
For swimmers, the advice is simple: Stay in designated areas. Avoid swimming at dusk or dawn when predators are most active. And if you have a cut, stay out of the brackish water.
The Verdict
The Delaware River is a complex, wild artery of the East Coast. It isn't a swimming pool. It’s a massive habitat.
Yes, there are sharks. Yes, they are mostly in the bay. Yes, Bull sharks can and do venture into the river proper. But they aren't "infesting" the water. They are a tiny, mostly invisible part of a massive underwater world that includes shipwrecks, sturgeon, and the occasional lost harbor seal.
Actionable Next Steps:
- Check Water Quality: Before swimming in the Delaware, always check the DRBC (Delaware River Basin Commission) reports for bacteria levels, which are a far greater risk than wildlife.
- Visit the Shore: If you want to see these animals safely, the Adventure Aquarium in Camden actually uses water filtered from the Delaware River (after massive treatment) and features many of the species found in the local coastal shelf.
- Report Sightings: If you see something unusual, like a stranded animal or a massive breach, contact the Marine Mammal Stranding Center. They handle sea turtles and sharks too, and your data helps them track the health of the river.
- Understand the Tides: If you are on the river south of Trenton, remember it is tidal. The "sharks" move with these tides, often pushing further upstream on a strong flood tide. Plan your boating or kayaking with this movement in mind to stay safe from the currents.
The river is cleaner, the fish are back, and the sharks are just doing what they've done for millennia. Respect the water, and you'll be fine.