Common names: Basking shark, elephant shark, bone shark, nurse shark, sunfish, sailfish, hoe-mother
French common names: Requin pèlerin, squale pèlerin, squale géant, éléphant de mer, poisson à voile
Scientific name: Cetorhinus maximus

Cetorhinus maximus roughly means “great-nosed sea monster” in Greek and Latin. Cetorhinus is derived from the Greek ketos (“sea monster”) and rhinos (“nose”), while maximus is Latin for “great” or “largest.”

• Occasionally observed swimming in slow circular formations with other basking sharks, a behaviour thought to be associated with courtship or reproduction.[2]
• Seasonal visitor to Atlantic Canada and Québec, including the Gulf and Estuary of the St. Lawrence.

Basking sharks are among the shark species most frequently mistaken for white sharks when observed from a boat or shoreline. Both species often swim close to the surface with their dorsal fin exposed, especially in the coastal waters of Atlantic Canada and the Gulf of St. Lawrence. At a distance, the two can appear surprisingly similar, but several features help distinguish them.

The dorsal fin of a basking shark is generally broader and more rounded, with a smooth, curved rear edge. In contrast, the fin of a white shark is usually taller and more pointed, often with a straighter or jagged trailing edge. White sharks also typically display a more distinct two-tone coloration, with a dark upper body and sharply contrasting white underside, whereas basking sharks tend to appear more uniformly coloured.

Unlike the predatory white shark, the basking shark is completely harmless to humans. It is a slow-moving filter feeder that swims with its enormous mouth open to strain plankton from the water. Despite its massive size, the basking shark poses no threat to people and is often one of the most gentle giants encountered in Atlantic Canadian waters.

The basking shark is found in almost all of the worlds’ oceans. Its American habitat extends from the North Atlantic off Newfoundland, to the South Atlantic. In Québec, the basking shark is found in the St. Lawrence Gulf and Estuary in the summer and fall. It is frequently observed off the Gaspé Peninsula, especially in the Bay of Chaleur, where recreational boaters and fishers have increasingly been reporting basking shark encounters by posting video and photos on social networks. Specimens have been captured by trawlers in the dead of winter, which may be an indication that a certain number remain in the Gulf of St. Lawrence year-round. A basking shark tagged in the UK was even tracked by satellite as it swam across the North Atlantic, almost reaching the coast of Labrador.

Although the basking shark feeds exclusively by filtering plankton, it possesses hundreds of tiny teeth in both the upper and lower jaws. These teeth are so small that they are usually noticeable only at close range on stranded or captured specimens. Their function in adults remains uncertain, but they may help developing embryos feed on unfertilised eggs produced by the mother (oophagy) before switching to filter feeding after birth[1].

The basking shark feeds primarily on plankton, including copepods, fish eggs, and other small drifting organisms. As it swims slowly near the surface, it filters enormous quantities of seawater through its gills, processing an estimated 2,000 tonnes of water per hour while travelling at speeds of roughly 2 knots (3.7 km/h; 2.3 mph).

Plankton-rich water enters the shark’s cavernous open mouth and passes across specialised gill rakers lining the gill slits, where prey is trapped before the filtered water is expelled.

The basking shark is ovoviviparous. Developing embryos are nourished first by a yolk sac and later by unfertilised eggs produced by the mother (oophagy). The tiny teeth present in embryos may assist during this stage before becoming largely unnecessary after birth, when the shark switches to filter feeding[1].

Reproduction in the basking shark remains poorly understood. Gestation is estimated to last between two and three years, making it one of the longest known among sharks[2]. Pups are born fully developed at lengths of approximately 1.5 to 2 metres (4.9–6.6 ft). Litter size is believed to be small, around six pups, although reproductive biology remains difficult to study because only one pregnant female has ever been scientifically described. Courtship, mating, and pupping are all thought to occur in shallow coastal waters during the summer months.

Current estimates suggest that the basking shark may live for at least 50 years[1], although its exact lifespan remains uncertain because the species is difficult to age accurately.

According to the St. Lawrence Shark Observatory’s Canadian Shark Attack Registry, no deliberate attacks on humans have ever been attributed to the basking shark. Most documented incidents have involved people approaching too closely and being struck accidentally by the powerful caudal fin (tail), or coming into contact with the shark’s rough skin. The skin is covered with large dermal denticles that can inflict abrasions or cuts on divers and researchers[1].

The basking shark is no longer targeted by fisheries in Canada or the United States, and many directed fisheries elsewhere in the world have also been closed. Nevertheless, limited fisheries still exist in some regions, particularly in parts of Asia, where the species is sought for its liver oil, meat, cartilage, and fins. Additional mortality occurs through bycatch and the illegal shark fin trade.

In British Columbia, basking sharks were deliberately hunted to near-extirpation during the mid-twentieth century by government patrol vessels and fishers, which viewed the species as a competitor for commercially valuable fisheries. Thousands are believed to have been killed during this eradication campaign.