At present, the target catch within pelagic longline fisheries is only a handful of the more than 70 species of fish taken during these operations. However, a considerable number of non-target species are marketed in Australia and elsewhere as a byproduct. While considerable attention has been focussed on target species and, in recent years, on bycatch species, assessment of the threats to, and opportunities for, the sustainable development of the harvest of byproduct species in Australia's tuna and billfish fisheries is long overdue. In particular, these species may represent significant opportunities for increased production from Australia's commercial fisheries including supply to export markets.
One of the key aims of the Commonwealth's Bycatch Action Plan (BAP) for Australia's tuna and billfish fisheries is the development of mechanisms to convert bycatch into byproduct where appropriate. One of the key impacts on the sustainable utilisation of these species are the current suite of Offshore Constituional Settlement (OCS) agreements that describe catch limits for many species taken in Australia's tuna and billfish fisheries. Analysis of spatial and temporal trends in catch and effort data for byproduct species would greatly assist future actions under the BAP including OCS re-negotiations.
In addition, management action taken to address issues facing target or bycatch species (e.g. spatial and/or temporal closures) may have considerable impacts on the take of economically-important, byproduct species. A wholistic approach is required and this approach needs to be supported by complete information from the fishery including all available information on byproduct species. As evidence for the significance of byproduct species to operators and managers it should be noted that operators in the Eastern Tuna and Billfish Fishery have launched legal proceeding against AFMA twice since 1999 specifically in relation to byproduct species (i.e. southern bluefin tuna and pelagic sharks).