Towards Ecosystem-Based Fisheries Management in an Economically Constrained Context: Giving More Consideration to the Ecosystem Approach to Fisheries Management

Achieving ecosystem-based fisheries management (EBFM), which seeks to optimise fisheries catches whilst maintaining the structure and functioning of ecosystems, is becoming more challenging in the current context associated with budget cuts and the restructuring of many research and management institutions. As such, more consideration could be given to the ecosystem approach to fisheries management (EAFM) which focuses on individual fisheries, to build strong foundations for EBFM. Here, we report an approach we developed to identify relevant tools to assist EAFM in New Zealand, towards EBFM. We present it and demonstrate it through an application to the west coast South Island (WCSI). Our application includes principal component analyses (PCAs) and heatmaps on landing compositions from the WCSI mixed bottom trawl fishery and research survey biomasses. Analyses indicated that the last 34 years can be divided into four clusters, starting with a period where the biomasses and landings of flatfishes and associated bycatch species were particularly high and ending with a period where the biomasses and landings of the commercially valuable snapper (Chrysophrys auratus) and red gurnard (Chelidonichthys kumu) increased markedly. Using the literature and knowledge from resource managers and stakeholders, we were able to interpret the clusters of years in light of changes from natural or anthropogenic causes. For example, the increased snapper biomass and landings in the most recent years may be partly explained by warming and more regular marine heatwaves that benefited the snapper population. The tools we identified will help progress EAFM in New Zealand and can support current management in several ways. In particular, user-friendly visual analyses based on PCAs and heatmaps and métier analysis can contribute to a better framework for defining fisheries, by delivering an understanding of catch composition as an emergent property of fisheries. We recommend further applications of the tools we identified in New Zealand, and our approach can also be adapted in other world regions.