The spiny dogfish, or "Squalus acanthias," is a small shark widely found in the salt and brackish waters of the North Atlantic, including in Quebec. Although it is not the most sought-after fish for sport anglers, it still piques some interest for those venturing into the coastal waters of the Saint Lawrence. Its moderate fighting ability and capacity for long battles make it an interesting opponent, especially for anglers seeking a different experience. It is primarily found in the Gulf and Estuary of the Saint Lawrence, where it moves in schools, often searching for small fish and crustaceans. Although its fishing is not particularly popular, the spiny dogfish is an excellent example of the diversity of marine species in Quebec.

The spiny dogfish has a streamlined body that gives it great agility in the water. Its color is generally dark gray to gray-blue on the back, lightening on the sides and becoming almost white on the belly. It is easily recognizable by its two dorsal fins, each equipped with a venomous spine at the base. Its mouth is located ventrally, typical of sharks, with small, sharp teeth adapted to its carnivorous diet. The pectoral fins are well-developed, while the caudal fin is heterocercal, with a longer upper lobe. Young dogfish are similar to adults but generally paler. Males and females are difficult to distinguish with the naked eye, except during the breeding season when males develop claspers, visible copulatory appendages. This species does not exhibit marked sexual dimorphism outside the spawning period.

The spiny dogfish is primarily present in the Gulf and Estuary of the Saint Lawrence. It is often found near the coasts, in shallow waters, but can also descend to depths of up to 650 feet. Although it is more abundant in maritime regions like Côte-Nord and Gaspésie, it is relatively rare in the fresher or colder waters of northern Quebec. Its distribution generally follows that of the fish schools it feeds on, which can vary depending on the seasons and water conditions.

The spiny dogfish prefers salty or slightly brackish waters, often near coasts where food is abundant. It frequents sandy or muddy bottoms but does not hesitate to explore rocky structures where small fish and crustaceans hide. It generally moves between the surface and a depth of 650 feet, although most catches occur in waters 65 to 330 feet deep. The ideal temperatures for the dogfish range from 45 to 59 °F, which explains its preference for the colder waters of the North Atlantic.

The spiny dogfish has a relatively long life cycle for a fish. It reaches sexual maturity around 12 to 14 years, which is late compared to other species. Females give birth to live young after a gestation of 18 to 24 months, one of the longest among fish. Each litter usually consists of 1 to 20 pups, depending on the size of the female. Young dogfish remain in shallow waters to protect themselves from predators and grow slowly, reaching adult size after several years. Spring: mating and gestation. Summer: continuous gestation. Autumn: birth of young. Winter: slow growth in deeper waters.

The spiny dogfish is a gregarious fish, often observed in large schools, especially when hunting. It is not particularly territorial and can travel great distances in search of food. Generally, it is unresponsive to noise and weather changes, but it tends to avoid overly turbulent or clear waters. It prefers to hunt in low-light conditions, such as dusk or dawn, making it less visible to its prey.

The diet of the spiny dogfish varies with age. Young ones primarily feed on small crustaceans and marine worms. As they grow, their diet expands to include larger fish such as herring, flounder, and even other small sharks. Adults are opportunistic predators, able to adapt to the available prey depending on the season. In spring and summer, when food is abundant, they eat more frequently, while in winter, their metabolism slows down, reducing their food needs.

In spring, the spiny dogfish is active, taking advantage of rising temperatures and abundant prey. The best times to fish for it are early in the morning and late in the day. In summer, it moves closer to the shores, although very hot days can drive it to seek cooler waters at depth. Autumn is a transitional period when dogfish prepare for winter, reducing their activity. In winter, they descend into deeper, colder waters, making them harder to catch. Weather conditions, like overcast skies or stable atmospheric pressure, can influence their behavior, making them more or less active.

To fish for the spiny dogfish, choose lures with natural colors like blue, green, and white, which mimic baitfish. In clear water, opt for more subtle colors, while in murky water, brighter colors may be necessary to attract attention. Lures with metallic reflections can also be effective, especially on sunny days, as they mimic the scales of shiny fish underwater. In deep water, go for heavier lures that can sink quickly.

To fish for the spiny dogfish, a rod of 7 to 8 feet with medium to heavy power is recommended. A robust reel of size 4000 to 6000, with good line capacity, is ideal for handling fights. Use a braided line of 20 to 30 lb for its strength and sensitivity. Hooks of size 2/0 to 4/0 are suitable, with a steel leader to avoid cuts from the sharp teeth of the dogfish. Ensure your equipment is well maintained to avoid breakage during prolonged fights.

When handling the spiny dogfish, be careful of the venomous spines on its dorsal fins. Use gloves to grip it firmly without injuring yourself. If you wish to release it back into the water, minimize the time out of the water and support its body well. For a photo, hold it horizontally and avoid pressing its internal organs. Release it gently back into the water, holding it until it swims away on its own.

The main predators of the spiny dogfish in Quebec include larger sharks, such as the porbeagle, as well as some marine mammals like seals. Seabirds, such as gulls, can also attack young dogfish when they are near the surface.

The spiny dogfish is not currently endangered in Quebec, but it is subject to rigorous management to prevent overfishing. Regulations include quotas and minimum capture sizes. Catch and release is encouraged for unwanted or too small specimens to preserve the population.