5 Sharks Found in the North Sea – Is It Safe to Swim?

The North Sea is part of the northeast Atlantic Ocean. It is located off the UK’s eastern coast, north of the Netherlands, and to the southwest of Norway. This sea connects to the Atlantic Ocean via the English Channel and the Norwegian Sea. Both migratory and year-round resident shark species swim in these cool, temperate waters.

In this guide, we’ll discuss five species of sharks found in the North Sea and provide our perspective on sharing the ocean with these magnificent animals.

Sharks Found in the North Sea

1. Porbeagle Shark (Lamna nasus)

A species of mackerel shark in the Lamnidae family, the porbeagle shark (Lamna nasus) is a year-round resident of the North Sea. This cold-adapted shark is one of a few endothermic species, meaning this shark can generate and retain its body heat, regardless of a body of water’s temperature. It literally can raise its body temperature above that of the surrounding water temperature. As such, the porbeagle is able to comfortably cruise the waters of the North Sea, even as the water’s temperature dips into the 40s (or 4-10 degrees Celsius) during winter.

Like other species in the Lamnidae family, the porbeagle features a sleek, torpedo-like body, conical snout, and countershading. Note that its first dorsal fin has a large white patch on the trailing edge. The porbeagle can reach a maximum length of 12 feet, weigh over 500 pounds, and live up to 38 years.

An opportunistic feeder, the porbeagle feeds primarily on small and medium-sized bony fish and cephalopods like squid, a favorite. This shark is fairly shy, and interactions between humans and the porbeagle are quite rare and marked by the shark’s curiosity.

2. Greenland Shark (Somniosus microcephalus)

Despite its common name, the Greenland shark (Somniosus microcephalus) does not only live in the waters surrounding its namesake. Rather, this long-lived species of the Somniosidae (sleeper shark) family occurs throughout the waters of the Northern Atlantic and Arctic.

The Greenland shark tends to spend winters closer to shore and in shallower waters. During the summer, they may travel into cooler, open ocean waters and can dive down to about 7,000 feet. These elusive sharks can reach up to 23 feet in length, can weigh over 2,200 pounds, and, incredibly, are estimated to live for 500 years. They are a quite sluggish shark, moving slowly and silently through the waters. It is estimated that these sharks can only reach a max speed of 1.8 miles per hour.

This shark preys on squid, a range of coastal and pelagic fish, and some marine mammals such as seals and sea lions. Of note, however, is that they scavenge a variety of dead animals. Scientists have even found the contents of drowned horses, reindeer, and polar bears in their stomachs.

Much is speculated and unknown about this shark, but there have been no reported attacks by this shark on humans, according to the International Shark Attack File.

3. Atlantic Thresher Shark (Alopias vulpinus)

A highly migratory species, the Atlantic thresher shark (Alopias vulpinus) primarily travels through the North Sea from summer through early fall. They tend to prefer warm to temperate waters between 60-70 degrees Fahrenheit (15-21 degrees Celsius), but because they are endothermic, they can manage the colder temperatures often found in the North Sea.

This shark most commonly occupies shallow coastal and pelagic waters, although it will dive down to about 1,800 feet in search of food. A defining feature of thresher sharks is their elongated caudal (tail) fin, which they use as a weapon against prey. They can use their tail to both directly hit their prey and slap the water with such speed and intensity that it stuns nearby prey, such as schools of sardines.

While Atlantic thresher sharks are apex predators, they see no reason to hunt humans (no shark species does). Encounters between humans and these timid sharks are extremely rare and accidental.

4. Basking Shark (Cetorhinus maximus)

The second-largest shark and fish species, the basking shark (Cetorhinus maximus), can reach up to about 30 feet in length and weigh over 10,000 pounds. This gigantic filter-feeding shark migrates across the globe seeking out plankton populations, but it is typically present in the North Sea during the late spring and early summer months due to increased nutrient levels in the water from melting sea ice and runoff from northern European rivers.

While it feeds on these tiny organisms by filtering around 2 million liters or half a million gallons of water per hour through its gills, the basking shark has 1,500 teeth. Not to worry, their teeth aren’t designed to eat large prey or people—not that they would want to anyway.

They get their name from the fact that they appear to be sunbathing or basking in the sun when feeding near the surface of the water where plankton is more plentiful. Like the other sharks on this list, they are placid in demeanor but known to bump boats.

5. Starry Smooth-Hound Shark (Mustelus asterias)

Native to the northeast Atlantic Ocean, the starry smooth-hound shark (Mustelus asterias) does well in shallow waters and inhabits inshore and offshore continental and insular oceanic shelves down to about 600 feet.

This lovely little shark features star-like patterning along its back and upper sides and can grow up to 5 feet in length. Although it looks like an apex predator, the starry smooth-hound shark preys, not on fish, but on crustaceans by scouring the seabed and snatching them up with their small, blunt conical teeth and powerful crushing plates at night along sandy and gravelly bottoms as they are nocturnal feeders.

This species of shark does well in captivity. Like the other sharks on this list, they do not present any threat to people.

Is It Safe to Swim?

The short answer? Probably, as long as you can endure the cold temperatures. The North Sea’s average temperature is about 55 degrees Fahrenheit. However, as it pertains to swimming with sharks in the North Sea, the answer will depend on a person’s comfort with sharing the same space with them, although there is plenty of room in the North Sea for both humans and sharks.

It’s important to put the risk into perspective. Humans kill an estimated 100 million sharks annually, whereas about 5-8 people are killed by sharks each year globally, often accidentally. We’re not on the menu of these magnificent ocean predators.

If you want to further to reduce the minute risk of a shark bite or encounter while swimming in the North Sea, here are a few tips:

• Avoid swimming at dusk or dawn.
• Swim in groups.
• Use extra caution in murky water.
• Do not swim with flashy jewelry on.
• Remain calm and swim slowly and intentionally if you spot a shark.
• Avoid splashing, doggy-paddling, or swimming with pets.