Joint ASU-Hawaii State study reveals long-term human impacts on reef fish

By Arizona State University

A school of fish swims amongst healthy coral reefs in South Kona, Hawaii Island.
Photo by Greg Asner, Arizona State University Center for Global Discovery and Conservation Science

Resource fishes — species targeted for human consumption — play a key role in reef ecosystems long before they end up on the dinner table. In Hawaii, subsistence and recreational fishing of local resource fish represent more than half of the share of annual reef seafood consumption, while also playing a vital role in indigenous cultural life.

These same fishes also help reefs to stay healthy by removing algae from coral surfaces, which in turn, helps coral recover from bleaching. Given the beneficial relationship between resource fishes and corals, determining how local pressures impact resource fish biomass is necessary for improving reef conservation and management.

In a new study investigating human impacts on resource fish biomass on the island of Hawaii, researchers from the Arizona State University Center for Global Discovery and Conservation Science and Hawaii Division of Aquatic Resources observed an alarming 45% decrease in fish biomass over a decade of surveys. The scientists proposed actionable solutions to mitigate future losses. The study was published Aug. 5 in Ecological Applications

The researchers investigated the influence of local factors on the nearshore resource fisheries of West Hawaii Island and compared the impact of distinct types of marine protections. They considered a range of factors including commercial and noncommercial fishing as well as nitrogen pollution from sewage disposal systems and golf courses. They also used ASU’s Global Airborne Observatory to map the 3D reef habitat to assess how it affects fish diversity, abundance and biomass. The researchers analyzed extensive fish survey data collected by the Division of Aquatic Resources between 2008 and 2018 at more than 300 sites spanning 180 km of coastline.

“Resource fish have been greatly reduced over the past decade in West Hawaii. We see that negative impacts of nitrogen pollution can outweigh other habitat and land-use stresses on resource fish,” said Shawna Foo, a postdoctoral researcher at the Center for Global Discovery and Conservation Science and lead author of the study. Nitrogen effluent from sewage and golf courses contaminates nearshore waters, creating stress for corals, and was a major driver of resource fish declines documented in the study.

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Read the study in Ecological Applications here: