Even when an increase in mesh size is expected to increase the catch in the long term, the immediate effect is a loss of fish.
For example, for M. merluccius, it is estimated that the immediate effect of an increase in mesh size from 40 mm to 60 mm would be a loss of catch of 17 percent. For an increase from 40 m to 70 m, the immediate loss would be about 25 percent.
After the meeting of the working group an assessment of the immediate and long-term effects of changes in mesh size were made in FAO headquarters, Rome, using a slightly different technique, see Appendix 8. The results are in close agreement with those found by the working group, particularly as regards the very considerable benefits that would arise from the use of a larger mesh size in the M. merluccius fishery.
