Effect of netting direction and number of meshes around on size selection in the codend for Baltic cod (Gadus morhua)

We investigated experimentally the effect that turning the netting direction 90° (T90) and halving the number of meshes around in the circumference in a diamond mesh codend had on size selection of Baltic cod. The results generally agreed with predictions of a previous simulation-based study. Both modifications had a significant positive effect on the size selection of cod. The best selection results were obtained for a codend in which both factors were applied together. For that codend, very little between-haul variation in cod size selection was detected, especially compared to the reference codend in which none of the modifications were applied.

Research highlights
► We investigated experimentally the effect that turning the netting direction 90° (T90) and halving the number of meshes around in the circumference in a diamond mesh codend had on size selection of Baltic cod.
► The results generally agreed with predictions of a previous simulation-based study.
► Both modifications had a significant positive effect on the size selection of cod.
► The best selection results were obtained for a codend in which both factors were applied together.