The Esmark cod, although little known to sport fishermen, is a fascinating species from the cold waters of northern Quebec. This bottom fish is more often studied by ichthyologists than targeted by anglers, due to its deep habitat and low fighting ability. Its distribution is mainly circumpolar, with populations observed in the brackish and salt waters of northern regions. Its presence in Quebec is mainly noted in the estuaries and marine waters of the St. Lawrence estuary.

The Esmark cod has an elongated, serpentine body with a relatively small, flattened head. Its color ranges from grayish-brown to olive green, often with marbling or dark spots that allow it to camouflage itself in rocky and sandy bottoms. The pectoral fins are well developed, while the dorsal and anal fins extend almost the entire length of the body, merging towards a tapered tail. The scales are small and barely visible, giving the skin a smooth texture. Young fish may be slightly lighter than adults, but there are no marked differences between males and females, even during spawning.

In Quebec, the Esmark cod is primarily found in the estuary and Gulf of St. Lawrence, as well as in some sheltered bays in northern regions. Its abundance is relatively low due to its preference for deeper, colder waters. This species is not present in fresh waters, limiting itself to marine and brackish areas where temperatures are low. Its general distribution extends across the circumpolar waters of the North Atlantic.

The Esmark cod prefers deep, cold waters, often beyond 50 meters in depth. It frequents rocky, sandy, or muddy bottoms, where it can hide and hunt its prey. The ideal temperatures for this species are between 2 and 8 °C, which explains its presence in northern regions. To find it, look in crevices or under stones where it camouflages itself to escape predators and catch prey.

The spawning of the Esmark cod generally occurs at the end of winter or the beginning of spring, when temperatures are still low. Females lay adhesive eggs on rocky substrates, where they are protected until hatching. The larvae, once hatched, feed on zooplankton and spend several months drifting before settling on the bottom. Growth is slow, and these fish reach sexual maturity between 3 and 4 years. Spring → Spawning → Summer → Growth → Autumn → Preparation for winter → Winter → Spawning

The Esmark cod is a solitary fish, spending most of its time hidden in crevices or among rocks. It is not particularly territorial, but it defends its immediate space against intruders. Sensitive to changes in light, it prefers low-light conditions and is more active at night or during overcast weather. Variations in temperature or pressure have little impact on its behavior, due to its deep habitat.

The diet of the Esmark cod varies with age. Young fish primarily feed on zooplankton, while adults consume benthic invertebrates such as small crustaceans, mollusks, and worms. In winter, when prey is scarcer, it may also target small fish. This diverse diet allows it to survive in environments where food resources are limited.

Due to its deep habitat, the Esmark cod is little affected by the surface seasons. However, it is more active during the colder months, from autumn to winter, when water temperatures are closer to its optimum. The best times to observe or catch it are generally at night or early in the morning. Weather conditions such as cloud cover and moderate winds can enhance its activity, as they reduce the light penetrating the water.

For the Esmark cod, using lures is generally not recommended, as it is more responsive to natural baits. However, if you opt for lures, prefer dark or natural colors that blend into the marine environment. Jigger lures can be effective in murky or low-light waters.

To target the Esmark cod, a robust rod of 2 to 3 meters is recommended, with a medium-heavy power to support the weights needed for deep fishing. A spinning reel filled with 20 to 30 lb braided line allows you to feel light bites well. Circular hooks sized 2/0 to 4/0 can be used with fluorocarbon leaders for maximum stealth.

Handle the Esmark cod with care, avoiding excessive stress. Use wet gloves to protect its sensitive skin. If you release it back into the water, do so quickly and gently. For a photo, support its body without squeezing, and take the photo quickly to minimize its time out of the water.

The main predators of the Esmark cod are larger fish like cod and some opportunistic seabirds. Seals may also prey on adults in deeper waters.

The Esmark cod is not currently a species at risk in Quebec. However, its capture is rare and often accidental. It is important to respect local regulations and practice catch and release to preserve this uncommon species.