Depth-distribution of deepwater species in Flemish Pass

Abstract

The depth-distribution of the main deep-sea fish species in Divisions 3LMN of the NAFO Regulatory Area is analysed using data from a longline survey carried out between 708 and 3 028 m depths in 1996. The results indicate that the most commercially important deep-sea species, Greenland halibut and roughhead grenadier, were only distributed up to 2 000 m depth. Below this depth another deep-sea species, the armed grenadier, replaced Greenland halibut and roughhead grenadier. The species which showed the widest depth-distribution were blue antimora, smalleyed rabbitfish and skates (700 m to about 3 000 m). Two species, the roughhead grenadier and the blue antimora, made up more than 60% of the catch in weight. Depth was the factor which most influenced the distribution of the species, affecting both yield and mean length of the catch. Mean length of the catch increased with depth in the majority of species. The yield of all species combined increased with depth between 700 and 1 500 m, where it reached a mean yield of 536 kg per 1 430 hooks. Below this depth the yield diminished.