The effects of commercial fishing on seamount biodiversity: an analysis of New Zealand policy

Abstract

Although hidden from the view of most New Zealanders, approximately 800 undersea "mountains" are peppered throughout New Zealand waters. Many of these seamounts host remarkably diverse benthic communities, including corals and sponges, which favour the hard substrate and swift currents of the features. Seamounts are also the main commercial fishing grounds for orange roughy, a lucrative deepwater species that is caught by dragging heavy trawl gear down seamount flanks. In 2001 the Minister of Fisheries banned trawling on 19 deepwater seamounts in New Zealand's exclusive economic zone based on concerns that the effects of fishing on benthic biodiversity and habitat were substantial and long-lasting. This study uses economic and ecological theory to examine government intervention on seamounts and the selection of spatially-based management measures to achieve the sustainability mandate of the Fisheries Act 1996. It sets out goals and criteria, derived from international and domestic obligations and public policy norms, to which a seamount policy should aspire. Using the selected goals and criteria, outcomes are projected for the current implementation option and two alternative options. Analysis of the outcomes indicates that the current measures undertaken to address seamount biodiversity loss do not hinder present extractive utilisation patterns of seamount resources, but do little to provide for non-extractive uses. They rate poorly on substantive goals including sustainability, maintenance of biodiversity, ecosystem-based management, the precautionary principle, adaptive management, and economic efficiency. An alternative that seeks to diminish uncertainty through more strategic design and research is presented as an improvement on the status quo, but retains the weaknesses of the "representative sample" approach. The option to limit trawling to those seamounts already fished does not curtail present extraction, but proposes the greatest departure from the status quo by shifting the “onus of proof” from society to the agent of environmental change. Design of marine policy that that holds up to rigorous scrutiny against a robust set of goals and criteria will require adoption of such a paradigm.