Opening of the Norway pout box: will it change the ecological impacts of the North Sea Norway pout fishery?

The small-mesh Norway pout (Trisopterus esmarkii) fishery intensified in the northern North Sea during the 1970s. Concerns about juvenile gadoid bycatch led to the “Norway pout box” closure along the Scottish coast in 1977. To assess the justification of the box today and the potential current impacts of opening the box, we evaluate the closure effects on selected fish stocks by analysing high-resolution research survey and commercial fishery data.

The species- and size-specific distribution patterns in relation to environmental influencing factors are analysed for Norway pout and important bycatch species inside and outside the box. Relative distribution of benthic habitats is compared between inside–outside areas according to fish occurrence and fishery spatial footprint.

No area differences in fish size composition are observed. However, species abundance depends significantly on habitat and depth whose area distribution is not homogenous. The current fishery is mainly in deeper, muddy seabeds. Haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus) density is higher in shallow and sandy habitats, with a relatively larger area coverage inside the box.

If a box opening implies relatively more fishery in those habitats, then increased bycatch can be expected. Consequently, closure of certain benthic habitats may instead be better management, opening new fishing opportunities without risk.