The cutthroat eel, or Synaphobranchus kaupii, is a snake-like fish species that primarily inhabits the deep waters of the North Atlantic, including off the coast of Quebec. Known for its elongated shape and ability to adapt to extreme environments, it sparks scientific interest rather than sporting interest. It is not particularly favored by sport fishermen due to its low fighting ability and rarity in shallow waters. However, it plays an important role in the marine ecosystem as a predator and scavenger.

The cutthroat eel has an elongated, snake-like body typically reaching up to 120 cm in length. Its skin is smooth and covered with small, hard-to-see scales. It is grayish to brownish in color with lighter shades on the belly. Its head is relatively small with a wide mouth and sharp teeth adapted for grasping slippery prey. The dorsal, anal, and caudal fins are fused, forming a long continuous fringe that allows it to move with agility in the depths. The young are similar to adults, though often paler. There are no marked differences between males and females, even during spawning season.

In Quebec, the cutthroat eel is primarily found in the depths of the North Atlantic, off the coasts of Gaspésie and the Côte-Nord. It is not common in the St. Lawrence, where the waters are generally too shallow for its preferred habitat. This species is mainly observed by researchers and commercial fishermen operating in deep waters. Globally, it has a circumglobal distribution in the North Atlantic and Pacific Oceans, preferring abyssal zones.

The cutthroat eel prefers deep waters, usually at depths of 650 to 6,500 feet. It is often found near the ocean floor, in dark and cold environments. Ideal water temperatures for this species range between 39 and 50 °F. It is often associated with muddy or sandy seabeds, where it can easily hide and hunt. Fishermen can find it using deep-sea fishing techniques, although it is rarely specifically targeted.

The cutthroat eel begins its life as larvae drifting in ocean currents before metamorphosing into young eels. It reaches sexual maturity after 3 to 5 years. Reproduction occurs in the open sea, but the exact details of spawning remain poorly known due to the difficulty of observation in natural environments. Its lifespan is estimated between 8 and 10 years. In spring, adults sometimes move closer to breeding areas but remain mostly in deep waters during summer, fall, and winter.

The cutthroat eel is a rather solitary species, not forming schools. It is not territorial but prefers areas where food is abundant. It is relatively insensitive to changes in weather conditions due to its deep-water life, but it can be sensitive to pressure variations caused by storms. It spends most of its time hunting or resting in marine sediments.

The diet of the cutthroat eel mainly consists of small fish, crustaceans, and sometimes carrion. Young eels primarily feed on zooplankton and small prey. As they grow, they start hunting larger and more varied prey. Adults are opportunistic and can consume anything they find on the ocean floor, making them important for cleaning the seabed.

The cutthroat eel does not exhibit marked seasonality in its activities due to its life in deep waters where seasonal variations are less pronounced. However, it may be slightly more active in spring when ocean currents bring more food. It is generally more active at night when its potential prey is also more active. Surface weather conditions, such as atmospheric pressure or wind, have little impact on the cutthroat eel due to its habitat depth.

For the cutthroat eel, natural baits are preferred. However, if you opt for lures, choose dark or phosphorescent colors to mimic deep-sea prey. In deep and dark waters, lures that emit light or vibrate can attract the attention of this species.

To fish for the cutthroat eel, a sturdy rod of 8 to 10 feet with heavy power is recommended. A sea reel capable of holding a 30 to 50 lb line is necessary to support the depth and potential size of the eel. Use reinforced hooks sized 3/0 to 5/0 and a steel leader to withstand the eel's sharp teeth.

Handle the cutthroat eel with care, using gloves to avoid slipping and injuries from its teeth. If you catch an eel you do not wish to keep, make sure to release it quickly and gently to minimize stress. Take photos quickly and avoid keeping it out of the water for too long.

Predators of the cutthroat eel include large deep-sea fish such as sharks and certain species of large abyssal fish. Due to its habitat, it is less exposed to avian or terrestrial predators.

The cutthroat eel is not currently considered endangered in Quebec, but it is subject to the impacts of deep-sea commercial fishing. It is important to respect local regulations regarding deep-sea fishing to ensure population sustainability. Catch and release is encouraged for accidental catches.