Dr Carl O'Brien:
The problem is that the stocks in European waters, Icelandic waters and Faroese waters, and in the Barents sea for Norway, are assessed on a single-species basis. The reference points that we have in terms of biological reference points and harvest rates are determined on a single-species basis. Unfortunately, when you put your fishing net in the water, you cannot catch just cod or haddock, or if you try to fish for plaice you cannot catch just plaice; you end up with sole and other species, so you have the so-called mixed fishery problem.
The reference points themselves would be fine in an ideal world where you could fish for just those species. The mixed fishery issue is that you cannot simultaneously achieve all those single-species FMSY values. The approach that scientists have come up with is basically to ask, “Can you find a range around MSY?” The UK was very instrumental in this, and the Minister took our paper to Council in, I think, 2013—the first time we tried it with the Commission.
The idea was to look at ranges. Can you find a range of fishing mortalities that are consistent with high long-term yield? The value that ICES took was 95% of the maximum. Some academics, such as Ray Hilborn, take 80%, which ICES thought was going too far—that could give you quite high Fs. ICES is being quite constrained in the way in which it is trying to manage the mixed fisheries and the choke issues. The reason for the range is that it allows you to try to deal with some of the mismatches between the availability of fish on the ground and the fact that the gear may not be as selective as it needs to be.