The basking shark, or Cetorhinus maximus, is the second largest fish in the world after the whale shark. Although it is not a targeted species by sport fishermen due to its peaceful nature and diet, it generates great interest among marine wildlife enthusiasts. This giant of the seas is known for its impressive appearance and its method of filter feeding, primarily consuming plankton. In Quebec, its presence is sporadic, usually observed in the cold, nutrient-rich waters of the Gulf of St. Lawrence. Due to its size and feeding habits, the basking shark does not provide a fight in sport fishing, but it is a fascinating sight for nature watchers and divers.

The basking shark has a massive, streamlined body, often gray-brown to black in color. Its skin is rough, covered with small dermal denticles. It is distinguished by a large crescent-shaped mouth that can open very wide to filter water. Its pectoral fins are broad and pointed, while its dorsal fin is large and triangular. The tail is asymmetrical with a more developed upper lobe. Young basking sharks resemble adults, although smaller in size, and the differences between males and females are not obvious to the naked eye. Basking sharks do not display marked patterns, which can make their identification tricky from a distance.

In Quebec, the basking shark is mainly observed in the Gulf of St. Lawrence, particularly around Anticosti Island and the Belle Isle Strait. Although it is not abundant, it is regularly reported in these cold, plankton-rich waters. Observations are more frequent during the summer months, when plankton is abundant. The basking shark is absent from Quebec's inland waters and does not venture into the St. Lawrence River beyond Tadoussac.

The basking shark prefers cold, nutrient-rich coastal waters. It is often observed near the surface, where it follows concentrations of plankton. Although it can dive to great depths, it spends a lot of time in shallow waters, especially during feeding periods. Basking sharks are often seen near ocean fronts and tidal currents that concentrate plankton.

The reproduction of the basking shark remains poorly understood, but it is believed to be ovoviviparous, with young being born alive after developing in eggs inside the mother. Growth is slow, and young basking sharks reach sexual maturity between 12 and 16 years. With a lifespan of up to 50 years, these sharks have a long life cycle. Spring → Spawning and surface feeding → Summer → Peak observations and intensive feeding → Autumn → Migration to deeper waters → Winter → Less active, in deep waters.

Basking sharks are generally solitary, although they may be observed in small groups, especially when feeding. They are not territorial and often move large distances in search of food. Sensitive to changes in water temperature, they follow concentrations of plankton that vary with the seasons and currents. Their behavior is little influenced by noise or light, and they continue to filter water even in rough weather.

The basking shark feeds almost exclusively on plankton, which it filters through its gills by swimming slowly with its mouth open. Both young and adults have the same diet, but young sharks may occasionally consume small fish or crustaceans. In spring and summer, when plankton is abundant, their feeding is more intense, while in autumn and winter, they may reduce their feeding activity and dive deeper.

Observations of basking sharks in Quebec are more frequent in spring and summer when plankton is abundant. They can be seen at the surface during sunny hours, but also in overcast weather. Wind and atmospheric pressure conditions do not significantly affect their surface behavior. In autumn, they begin to migrate to deeper waters and are less often observed, while in winter, they are rarely seen at the surface.

Although the basking shark is not fished, observing colors and movements in the water can help spot it. Clear waters make it easier to see their dark dorsal fin. In overcast weather, their silhouette may be harder to distinguish, while in sunny weather, it contrasts well with the water.

For observing basking sharks, a stable boat and quality binoculars are essential. A wetsuit is recommended for those wishing to observe underwater, due to the cold temperatures. No fishing gear is needed, but an underwater camera can be valuable for documenting the sighting.

It is highly discouraged to handle a basking shark due to its size and protected nature. If you observe a basking shark caught in a net or in distress, contact local authorities for appropriate intervention. Always maintain a safe distance for the well-being of the animal and your safety.

Adult basking sharks have few natural predators due to their size. However, young sharks may be vulnerable to large sharks and orcas. Interactions with humans, particularly through boats and fishing nets, pose a more significant threat.

The basking shark is a protected species in many regions due to its vulnerability to commercial fishing and habitat degradation. In Quebec, it is illegal to intentionally fish for it. Sightings should be reported to authorities to aid in the conservation and study of this fascinating species.