Studies on C. harengus were conducted in the N. Baltic to assess whether the mortality from escaping through a rigid sorting grid placed in front of the codend was different from that of escaping from a diamond mesh codend. On the basis of the results, the authors argue that a considerable part of the mortality observed may be attributed to mechanical contacts with the trawl netting and exhaustion during the capture process, and that damage can occur in the net long before fish reach the codend.