Abstract
In most trawl fisheries, drag forces tend to close the meshes in large areas of diamond mesh codends, negatively
affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based
on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp
is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting
codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not
affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile
fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected.
When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on
catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes.
affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based
on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp
is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting
codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not
affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile
fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected.
When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on
catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes.