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Research Spotlight: Long-term human impacts on reef fish in Hawaii

Shawna A. Foo,  William J. Walsh,  Joey Lecky,  Stacia Marcoux, Gregory P. Asner (2020). Impacts of pollution, fishing pressure, and reef rugosity on resource fish biomass in West Hawai‘i. Ecological Applications.

The Upshot

Resource fishes—species targeted for human consumption—play a key role in reef ecosystems long before they end up on the dinner table. They help reefs to stay healthy by removing algae from coral surfaces, which in turn, help 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

The Discovery

Researchers from the Arizona State University Center for Global Discovery and Conservation Science (GDCS) and Hawai‘i Division of Aquatic Resources observed an alarming 45% decrease in fish biomass over a decade of surveys. The researchers also found that different types of management resulted in different levels of fish biomass. They found significantly greater fish abundance and biomass in areas that banned spearfishing compared to areas that did not, likely due to the fact that four of the five most common species from the surveys are primarily caught by spears. Additionally, marine management areas with multiple bans on spearfishing, aquarium collection, and lay nets had the highest overall fish biomass compared to other managed or unmanaged areas, especially for herbivorous fish. The study was published in Ecological Applications.

The Impact 

“These results are among the clearest to emerge for Hawaiʻi. Based on the long-term monitoring efforts of our Hawaiʻi DAR partners, we were able to ascertain unequivocal evidence for a decline in shallow reef fish populations along the famous Kona coast of Hawaiʻi Island. We were also able to connect both the decline and the remaining fish stocks to specific actions that can be taken now to enhance the fishery and protect reefs. This is a triple win for science, management, and the fisher community.” - Greg Asner, Director of GDCS.

The Researchers

Shawna A. Foo is a postdoctoral researcher at GDCS,  William J. Walsh a researcher at Hawai‘i Division of Aquatic Resources,  Joey Lecky is a researcher at Lynker Technologies LLC, Marine, Ocean, and Coastal Science and Information Group,  Stacia Marcoux is a Fish and Habitat Monitoring Technician at Hawai‘i Division of Aquatic Resources, Pacific Cooperative Studies Unit, and Gregory P. Asner is the Director of GDCS