Evaluating anthropogenic threats to the Northwestern Hawaiian Islands

Abstract

Abstract Every manager must assess and prioritize anthropogenic impacts on their management area from a long list of threats, but data which allow comparison of the relative ecological impacts of threats for decision‐making is often unavailable. This study employed a systematic and standardized method to collect and quantitatively synthesize expert opinion on the ecological effects of anthropogenic threats to the world's largest marine protected area: the Papahānaumokuākea Marine National Monument (MNM) in the Northwestern Hawaiian Islands (NWHI). In contrast to most threat ranking exercises, the method provides detail on the reasons behind a particular ranking of threats to an area and why the ranking may vary across the ecological landscape. Survey results from 25 experts allowed the comparison of the vulnerability of eight NWHI ecozones to 24 anthropogenic threats in a quantitative manner. Ecozones tended to have distinct top threats: sea‐level rise was identified as the top threat to rocky intertidal, beach and terrestrial ecozones; sea temperature rise was the top threat to the coral reef ecozones; bottom fishing was the top threat to the deep reef/bank ecozone; and pelagic fishing in the wider Pacific was the top threat to the pelagic ecozone owing to impacts on bird, turtle and fish fauna that forage outside the Papahānaumokuākea MNM boundaries. Many of these top threats are difficult for local managers to control because they arise from activities outside the Papahānaumokuākea MNM boundaries, indicating that additional work is needed to preserve the NWHI despite its highly protected status. The analysis indicates where inter‐agency cooperation in removing and mitigating threats should be focused. Copyright © 2008 John Wiley & Sons, Ltd.