Marine Species: Basking Shark

The basking shark is the world’s second-largest shark species, after the whale shark. The sharks have been recorded reaching an astounding length of 40 feet (12 m). These filter-feeders cruises slowly on the surface during the summer months, consuming huge mouthfuls of tiny planktonic creatures, much like baleen whales.

Where to see basking sharks

While basking sharks are well-managed and protected in Europe, their status worldwide is vulnerable. In certain parts of the world, such as the North Atlantic, they are classified as endangered due to heavy fishing between 1946 and 1995, when the sharks were killed for their meat, liver oil and large fins. It is now illegal to catch basking sharks and doing so will result in a 6-month imprisonment and a large fine in Britain.

Basking shark anatomy and conservation

The shark’s liver, which fishermen so prized during the mid-part of the century, is a key feature of its anatomy. Covering 25 percent of the shark’s body, the liver is a fundamental organ that regulates their buoyancy and energy storage.

Basking sharks give birth only once every two to four years, to litters of around six pups. Because of that long gestation period and with a life expectancy of around 50 years, basking shark numbers have been slow to recover.

Basking sharks migrate thousands of miles, cruising at depths of 700 to 3,300 feet (200 to 1000 m) along continental shelves, only ascending to the surface for certain months of the year.

The sharks most recognizable and famous feature is its enormous mouth, capable of engulfing up to 396,000 gallons (1.5 million liters) of water per hour. Because of their size, basking sharks must eat large quantities of plankton and fish eggs to survive. Preferring water temperatures ranging from 46 to 58 F (8 to 15 C), it’s no surprise that they are seen in northern and southern latitudes further away from the equator where plankton stocks are minimal.

The slow-moving basking sharks are not shy of marine craft. They have even been spotted breaching from the water, perhaps to dislodge parasites or as a form of communication or display to other sharks in the area. Usually a solitary species, basking sharks are known to form groups of up to 100 individuals during summer months when lucky snorkelers might see multiple huge dorsal fins protruding from the surface.