The stout knifejaw, or Serrivomer beanii, is a little-known species from the deep waters of the Saint Lawrence. This eel-like fish is rarely targeted by sport fishermen due to its difficult-to-access habitat and low fighting potential. It is mainly of interest to researchers and ichthyology enthusiasts interested in the diversity of marine species in Quebec. Its distribution is primarily in the deep, cold waters of the Gulf of Saint Lawrence, where it mingles with other bathypelagic species. Although discreet, the stout knifejaw plays an important role in the marine ecosystem as an opportunistic predator of small fish and invertebrates.

The stout knifejaw features an elongated, serpentine body, typical of the eel family. Its color ranges from dark brown to blackish, allowing it to blend into the dark depths of its habitat. The patterns on its body are generally faint, but slight silver hues can sometimes be observed. The mouth is wide and equipped with sharp teeth, suited for grasping its prey. The pectoral fins are reduced, and its dorsal fin extends over a large part of its back, merging with the caudal fin. The scales are small and not easily visible. Young individuals resemble adults but are often lighter and more translucent. There is no apparent sexual dimorphism between males and females, even during the spawning period.

In Quebec, the stout knifejaw is mainly found in the Gulf of Saint Lawrence, where it inhabits deep waters. It is also sporadically encountered in certain areas of the Saint Lawrence River watershed, but it is absent from shallower and less deep waters. Its distribution is limited by its preference for cold marine environments, usually below 200 meters deep. This species is scarce and difficult to observe, making it more of a study subject than a target for recreational fishing.

The stout knifejaw prefers the deep waters of the Gulf of Saint Lawrence, where it finds ideal conditions for its lifestyle. It frequents bathypelagic zones, often at depths of 200 to 1000 meters, where temperatures are low and light is nearly nonexistent. It hides among rocky structures and muddy bottoms, taking advantage of the dimness to hunt its prey. Fishermen wishing to observe it will need to target these specific areas, usually with specialized equipment for deep waters.

The reproduction of the stout knifejaw remains partially mysterious, but it is known to spawn in deep waters. The eggs are likely left to drift in marine currents until hatching. The larvae, called leptocephali, drift in pelagic waters before becoming juveniles and joining the deeper zones where adults live. Sexual maturity is reached around the age of 3 to 4 years, and the species' longevity is relatively short, at 4 to 6 years.

Spring: Spawning → Summer: Hatching → Autumn: Juvenile growth → Winter: Adult life in depth

The stout knifejaw is a rather solitary fish, rarely moving in groups. It is not particularly territorial but avoids areas too frequented by other predators. It is sensitive to changes in light and prefers dark environments. Disturbances in the environment, such as loud noises or sudden temperature changes, may drive it to move to calmer areas. It is primarily active at night, taking advantage of the darkness to feed.

The diet of the stout knifejaw consists mainly of small fish and invertebrates that it hunts in the depths. Young individuals feed on zooplankton and other small organisms, while adults target larger prey, such as lanternfish and small crustaceans. Its hunting strategy is opportunistic, using its dark color and discretion to approach prey undetected.

The stout knifejaw is active year-round, but its hunting periods vary with the seasons. In spring and summer, it takes advantage of slightly higher temperatures to increase its feeding activity. In autumn and winter, although temperatures are colder, it maintains a constant level of activity due to the abundance of prey in the depths. The best times to observe it are at night when it is most active, and it is minimally affected by weather conditions due to its deep habitat.

Although sport fishing for the stout knifejaw is not common, if you were to attempt to attract it, opt for lures mimicking its natural prey, such as small fish or crustaceans. In dark waters, phosphorescent lures could be effective. In clearer waters, natural and discreet colors are preferable.

For observations or studies, a robust rod for deep fishing is necessary, although sport fishing is not practiced for this species. Use a reel capable of withstanding the pressure of deep waters and a strong line of 20 to 30 lb. Hooks should be suited to the size of the stout knifejaw's usual prey.

If you capture a stout knifejaw for study, handle it carefully to avoid injuring it. Use gloves and minimize the time out of the water. For release, ensure it is healthy and able to dive quickly.

In the depths of the Saint Lawrence, the stout knifejaw must be wary of predators such as certain sharks and large carnivorous fish. Seabirds pose no threat due to the species' deep habitat.

The conservation status of the stout knifejaw in Quebec is of little concern, but its specific habitat makes it vulnerable to environmental changes. Catch limits should be enforced for scientific purposes with strict regulations to preserve local populations.