SURVIVAL OF YOUNG GADOIDS EXCLUDED FROM A SHRIMP TRAWL BY A RIGID DEFLECTING GRID

The survival of one-year-old cod (Gadus morhua), haddock (Melanogrammu s aeglefinus) and whiting (Merlangius merlangus), excluded from a shri mp trawl by a diagonal metal grid placed in front of the codend (the N ordmore grid), was studied during June 1993 and 1994. Fish leaving the gear in front of this grid during trawling were retained by a net cov ering the fish outlet, and led into a collecting cage. The collecting cages were released from the trawl at the fishing depth and anchored f or 5 to 12 days. The fish in the cages were then observed daily by und erwater television, and in the second season also by divers. The escap ees from separate trawl hauls were analysed for body damage. No mortal ity was found among the young gadoids during the observation period, e xcept for one haddock in the control group. There were almost no visib le skin injuries or scale loss in cod, while in whiting and haddock th ere was a significantly larger incidence of these factors. No correlat ion was observed between fish size and the amount of scale loss. (C) 1 997 International Council for the Exploration of the Sea.