State officials hope to increase public fishing opportunities off 'Ewa by building an artificial reef of at least 50 acres near Kalaeloa, while marine researchers are suggesting that the most important way to improve the number of marine species is simply to stop fishing in some areas by creating permanent marine reserves.

"Hawai'i's populations of reef fish have been decreasing for many years, largely as a result of human activities," says the state's draft environmental impact statement for its proposed Kalaeloa Artificial Reef. While runoff and dredging have impacts, fishing itself is a big problem, it said.

"Population growth has exerted pressure on fish stocks, and advanced technology has given commercial fisherman the ability to effectively exploit many coral reef fish species throughout their entire ranges," the report says.

The proposed concrete structures of the artificial reef would provide complex surfaces for corals, seaweeds and other species to populate, and provide food and hiding places for fish, lobsters and other marine creatures.

Meanwhile, a new study of marine reserves in the Islands shows that another way to improve the amount of marine life on the reefs is to select large enough areas and close them to fishing. The study, with the ponderous title "Fish Habitat Utilization Patterns and Evaluation of the Efficacy of Marine Protected Areas in Hawaii: Integration of NOAH Digital Benthic Habitat Mapping and Coral Reef Ecological Studies," found what you might expect: If you close an area to fishing, you end up with a greater overall mass of fish, bigger fish and more kinds of marine life in that area.

There were also a couple of other pieces of information in the report. You need to select the right kinds of areas with the right kinds of reef; the closed areas need to be big enough if you hope to spill excess fish into neighboring areas where they can be fished; and rotating closed zones doesn't work well.

The study, headed by Alan Friedlander, of NOAA's National Centers for Ocean Science and Oceanic Institute, an affiliate of Hawai'i Pacific University, looked at existing marine protected areas in Hawai'i and the adjacent unprotected waters.

Building reefs for more fishing and closing other areas to reduce fishing pressure may seem contradictory, but maybe they simply show that the science of improving nearshore marine production is complex and dynamic. And maybe they also show that someone ought to put all the ideas into a sensible framework.

If you have a question or concern about the Hawaiian environment, drop a note to Jan TenBruggencate at P.O. Box 524, Lihu'e, HI 96766 or jant@honoluluadvertiser.com. Or call him at (808) 245-3074.