Latin name

Coryphaenoides rupestris

Other names

Roundnose grenadier, roundhead rat-tail, grenadier de roche, granadero de roca.

Identification

Body elongated, tapering caudally to a thin filament, covered with fine cycloid scales with numerous denticles. From the middle of the base of the first dorsal fin to the lateral line there are 6.5 rows of scales. The tail fin is absent. The head is large, broad and high. The snout is short, broad and rounded, with a small tubercle at the end. It extends beyond the lower jaw. The length of the muzzle is less than the interorbital space. The chin strap is very small. Teeth on both jaws, small, conical in shape, larger in the three outer rows then in the single row behind. There are 6 rays in the gill rays. There are 13-21 gill stamens on the first gill arch. The abdomen is short. The anal opening is just before the beginning of the anal fin. Swim bladder large. There are 29-31 pyloric appendages, which are thin and elongated.

Fish fin structure

The first dorsal fin is high with a short base and two barbed rays, one of which is difficult to distinguish and the second is well developed with serrated edges. The first dorsal fin has 8-10 soft rays. The second dorsal and anal fins are long and low and continue to the caudal part of the body. The second dorsal fin has 103-183 soft rays and the anal fin has 104-187 soft rays. The rays of the second dorsal fin are shorter than those of the anal fin. The pectoral fins have 17-20 rays. The pelvic fins with 7-14 rays are located on the belly below the pectoral fins, the first ray is elongated, its length is almost equal to the length of the head. 

Fish colouring

The body is brown or greyish. The eye orbits, mouth, gill cavity and fins are dark purple to grayish brown.

Distribution

Widespread in subtropical, temperate and cold waters of the Atlantic Ocean. Eastern Atlantic: from Cape Hatteras to Baffin Land and Greenland. Western: from Iceland and Norway to North Africa (20°N) and in some places on the North Atlantic Ridge. Individual records have been made of the Bahamas and in the coastal waters of Mauritania.

Habitat

Marine gregarious bathy- and benthopelagic fishes. They live at depths from 180 to 2200 metres and are most commonly found between 400 and 1200 metres. They move to deeper water layers in summer and return to shallower depths in winter when water temperatures drop. They make daily vertical migrations, rising from the bottom to the water column at night in search of food.

Size

Slow growth is characteristic. The maximum length is 110 cm and the mass is 1.7 kg. At the same age, females weigh more than males.

Behavior

The locality of groupings or herds of these fish has not been studied. Some researchers believe that this species makes long spawning migrations to southern Iceland and then feeding migrations to the Canadian mainland slope, while others believe that this fish does not make long migrations and spawns close to the mainland slope in deep water. The maximum life expectancy of the rock grenadier is 54 years.

Food and feeding habits

Feeds on a variety of invertebrates and fish. Small invertebrates such as shrimps, amphipods, cumaceans and to a lesser extent cephalopods, various fish including lanternfish form the basis of the diet. In larger individuals, the proportion of fish and squid in the diet increases. The greatest feeding activity is observed in the morning and evening hours.

Reproduction

50% of males mature at 8-10 years with a body length (to anus) of about 10 cm, and females mature at 9-11 years with a body length of 12 cm. Spawning is portioned. The spawning season in populations is very long, lasting from July to November. Each female lays 3-4 portions of eggs in a short period of time. Males produce sperm repeatedly over several months. Eggs are bathypelagic, spherical, 2.8-3 mm in diameter, with a fat droplet. Fecundity ranges from 11,000 to 55,000 eggs. The larvae are pelagic, their fins have elongated rays. The larval stage is long, and only when they reach a length of about 10 cm does the period of juvenile growth begin.

Fishing

It is a valuable commercial fish. The flesh is very watery but has a pleasant flavour.