Cusk

The cusk is a solitary bottom-dwelling fish of the North Atlantic and a member of the cod-like fish group, though it is placed in its own genus, Brosme, within the related family Lotidae. It has a stout, elongated, almost eel-like body and is easily separated from true cods by its single unbroken dorsal fin. Cusk range from Arctic Canada and Iceland south to the mid-Atlantic coast of the United States, and across to Scandinavia and the British Isles. It favors cold water and rocky, uneven seafloor where it can shelter among boulders and crevices. Populations in parts of its range have declined due to bycatch pressure, and the species is considered vulnerable in some regional assessments, making accurate identification useful for monitoring efforts.

Cusk are recognized by a heavy, tapering body that looks like a cross between a cod and an eel.

• Single long dorsal fin running unbroken from just behind the head to the tail
• Long anal fin mirroring the dorsal fin along the lower body
• One short barbel on the chin
• Mottled yellowish-brown to reddish-brown coloration with a pale lateral line
• Thick, rubbery lips and a rounded tail fin

Unlike true cod or hake, cusk lack a divided dorsal fin and have no obvious notch between fin sections. Adults typically measure 50-90 cm, occasionally exceeding 1 meter. The combination of a single continuous dorsal fin and thick-lipped, mottled appearance separates it from red hake and white hake, which both show two distinct dorsal fin sections.

Cusk inhabit cold, deep waters of the North Atlantic, from the Gulf of Maine and Georges Bank north to Labrador, Iceland, and the Barents Sea, and east to Norway and the British Isles. They are strongly associated with rocky, uneven bottoms, boulder fields, and ledges where they can wedge into crevices, typically at depths of 100-400 meters, though they range from shallow rocky shorelines to over 1,000 meters. Cusk prefer water temperatures between about 3-10°C and rarely stray far from complex rocky structure, making them uncommon over soft mud or sand. Their deep, cold-water rocky habitat overlaps with species like grenadier and red hake but at generally shallower depths than true abyssal fishes.

Cusk are solitary, sedentary fish that spend most of their time resting near or within rocky shelter rather than swimming in open water. They are opportunistic bottom predators, feeding mainly on crustaceans, mollusks, and small fish located by sight and by sensing prey near the seafloor. Cusk are slow-growing and long-lived, with individuals reaching several decades of age, which makes populations slow to recover from fishing pressure. Spawning occurs in deeper offshore waters, where females release large numbers of buoyant eggs that drift and hatch in the open water column before juveniles settle onto rocky bottom habitat. As a solitary ambush-style predator tied to structured seafloor, the cusk plays a role in controlling benthic invertebrate populations within its rocky habitat.