Page "Trawling" Paragraph 16

Size selectivity is controlled by the mesh size of the " cod-end "— the part of the trawl where fish are retained.

Fishermen complain that mesh sizes which allow undersized fish to escape also allows some legally – catchable fish to escape as well.

There are a number of " fixes ", such as tying a rope around the " cod-end " to prevent the mesh from opening fully, which have been developed to work around technical regulation of size selectivity.

One problem is when the mesh gets pulled into narrow diamond shapes ( rhombuses ) instead of squares.