Fishing is driving enormous changes in Hawaii's nearshore fisheries populations, a study by six Hawaii fishery scientists shows.

“;There is a strong signal across the state that fishing is having a real impact,”; said Ivor Williams, lead author of the study published in the current issue of the scientific journal Environmental Conservation.

Near the main islands, the difference is threefold from the lowest to highest fish populations, he said in an interview.

Habitat degradation and coastal pollution are also important factors in populated, developed areas of Oahu, said Williams, with the University of Hawaii's Cooperative Fishery Research Unit on the Big Island.

But declining fish would have been seen across the board if the chief cause was habitat loss or environmental degradation related to development and pollution, he said. “;Instead, fish declines along human population trends were only really apparent for species preferred by fishers.”;

The preferred reef fishes - uhu, ulua and redfish - are severely depleted, with fishing the main cause, Williams said.

Fish populations were compared at 89 sites throughout the seven main Hawaiian Islands by Williams, co-author Alan Friedlander of the Oceanic Institute and NOAA National Ocean Service, William Walsh and Kosta Stamoulis of the state Division of Aquatic Resources, and Robert Schroeder and Benjamin Richards of the UH Joint Institute for Marine and Atmospheric Research.

Knowing that human activities on land can significantly affect the coastal environment, the researchers studied data from 128 fish surveys to separate fishing impacts from other human impacts.

In areas with more people and fewer fish overall, the species disappearing are those most prized by fishers, they reported. Hawk fishes, butterfly fishes and some small triggerfish and surgeonfish species that are not popular food items are doing better, the scientists said.

One of the most disturbing findings is the uhu, or parrotfish, biomass around Oahu sites was only about 3 percent of that in remote parts of the islands, Williams said.

Parrotfish are herbivores that control algae and maintain the health of reefs, and they are “;massively impacted by fishing,”; Williams said.

Friedlander said he was surprised that some remote areas, even around the main islands, still look quite healthy. “;The flip side is how poor conditions are in some populated areas as far as reef fish populations.”;

Waikiki and Hawaii Kai once were important nursery habitats for a lot of keiki fishes, he said. “;Those are gone because of a combination of many things.”;

Some people say parrotfish are still there but in deeper water because of fishing pressure, Friedlander said. “;You can argue that. ... What we do know is parrotfish are important contributors to overall reef health.

“;They're big grazers on the reef,”; he said. “;They produce a lot of sand and keep reefs clean. It is important for coral reefs to function properly. If they're in deeper water, you lose that ecological service.”;

Friedlander said a multipronged approach is needed to address the problems, and it will take time. Where appropriate, he suggests community-managed fishing areas. They have proved effective in a number of areas where communities have taken responsibility to manage their fishery resources in a more traditional fashion, he said.

The one thing almost everyone can agree upon, Friedlander added, is that “;enforcement is lacking greatly.”;