During the peak recruitment season (July–August) in 1984 and 1985 at Midway lagoon, Northwestern Hawaiian Islands, experiments were conducted to determine if either size or degree of isolation of artificial reef units affected fish recruitment rates. Small, standardized attractors
(coils of coarse wire mesh) were arranged on open sand flats at depths of 3 m to 6 m. To analyze the effect of reef size on recruitment rates, a group of six contiguous attractors (simulating a large reef) was compared to individual unit attractors (controls) about 100 m apart. To analyze
the effect of reef isolation, a set of six attractors (spaced 10 m from each other) was compared to the same controls. Newly recruited postlarval fishes were collected daily. Daily total recruitment to the large reef was about three times greater than to the small, single unit attractors,
suggesting that recruitment rate increases, although at diminishing densities, with reef size. Daily total recruitment to the widely isolated single unit attractors was higher than to the closely spaced attractors. Abundances of recently recruited fishes censused on neighboring, natural patch
reefs (much larger than attractors) increased with reef size. The effect of isolation on these natural reefs was confounded by the stronger effect of reef size. Results have value to efforts by managers to improve local fisheries by enhancing recruitment through use of artificial reefs or
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