A lightweight sorting grid was developed to reduce bycatch in the Danish small-meshed
trawl fishery (22 mm full mesh in the cod end) for Norway pout in the North Sea.
Experimental fishing with the grid demonstrated the possibility to capture Norway pout
with only a minimum of unintended bycatch. Fishing with two different grid orientations,
backwards and forwards-leaning, in distinct day and night hauls, resulted in an estimated
release of between 88.4 and 100% of the total number of haddock (Melanogrammus
aeglefinus) and whiting (Merlangius merlangus) entering the
trawl. However, bycatch reductions were not significantly different between day and night
or between grid orientations, indicating that the grid rejection of haddock and whiting is
not influenced by fish behaviour. The loss of the target species, Norway pout, was low
(between 5.6% and 13.7%) in comparison with the bycatch excluded, and clearly length
dependent. Consequently, loss of target species would vary with the size structure of the
population fished. Although results were not statistically significant, length-based
analyses indicated that the grid rejection likelihood for particularly smaller Norway pout
(<16 cm) was higher when fishing with the forwards-leaning grid during the night;
this might be explained by behavioural and visual aspects of the fish-grid encounter
process for Norway pout.