Hawaii & Alaska
A large school of surgeonfishes swims over a shallow Hawaiian reef. Noam Altman-Kurosaki / University of Hawaii at Manoa

HI - Oahu marine protected areas offer limited protection of coral reef herbivorous fishes

Marine protected areas (MPAs) around O'ahu do not adequately protect populations of herbivorous reef fishes that eat algae on coral reefs.

That is the primary conclusion of a study published in Coral Reefs by researchers from the University of Hawai'i at Mānoa School of Ocean and Earth Science and Technology (SOEST).

There are over 20 species of herbivorous fishes and ten species of herbivorous urchins commonly observed on Hawaiian reefs. These species eat algae that grows on reefs, a process called herbivory, that contributes to the resilience of coral reefs by preventing algae dominance that can lead to overgrowth of corals.

The team of researchers found that of the four marine protected areas around O'ahu they assessed in the study, three did not provide biologically significant benefits for herbivorous fish populations compared to reefs outside the areas.

"Marine protected areas are a fishery management tool to limit or prevent fishing to help the recovery and maintenance of fish abundance and biomass inside the MPA," said senior author Erik Franklin, Associate Research Professor at the Hawai'i Institute of Marine Biology in SOEST. "An effective MPA should lead to a considerably higher abundance and biomass of fishes inside the MPA boundaries that would otherwise be caught by fishers but that wasn't what our study found."

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