Both ICES and NAFO have had difficulties in deciding on how to set RPs in multispecies fisheries, and this is a major problem, given the multispecies nature of most of their fisheries. Some conclusions seem to emerge from this process, however:
Multispecies reference points which take into account impacts of the fishery not only on the target species but on its by catch-species, predators, prey and competitors, would normally have to be more conservative than if the target stock is considered alone. This is not only because there is a need under the Biodiversity Convention and UN Agreement to maintain self-sustaining stocks of all species concerned (including incidental captures) but because some of them (e.g. dolphins) probably require lower RPs in terms of fishing mortality than the target species. For most oceanic tunas, the prey species are rarely heavily exploited and predators are not well defined, so this problem seems somewhat simpler than for demersal fish assemblages, a situation that is far from the case for shelf fisheries.
Comparable considerations would seem to apply for shelf fisheries, and multi-species RPs could be derived from ecological/food web models.
