Application of underwater photography to study ecology of bottom commercial objects

On the basis of visual observations and underwater photography it was stated that cod (Gadus morhua L.), haddock (Melanogrammus aeglefinus) and roundnose grenadier (Macrourus rupestris Gunn.) had been concentrated in front of the net part of bottom and midwater trawls and the density of fish distribution in this zone is in direct linear dependence to that of their distribution under the environmental conditions. In contrast to fish, the northern deep-water shrimp (Pandalus borealis Kroüger) do not aggregate in front of a trawl aperture, that is due to some specific features of their response to the different parts of the bottom trawl rig. The data obtained can be used for assessment on absolute density of concentrations of bottom commercial objects and fishing efficiency of trawls.