Quantitative assessment of different artificial reef designs in mitigating losses to kelp forest fishes

Determining the success of artificial reefs as a tool for mitigating human-induced losses to fish populations requires explicit standards for performance assessment, and a robust monitoring program designed to collect the information necessary to evaluate those standards. Here we describe: (1) the biological performance standards established for kelp forest fishes on an artificial reef designed to compensate for the loss of kelp forest habitat caused by the operation of a coastal power plant in southern California, (2) results of a 5 yr experiment that tested the efficacy of six artificial reef designs in meeting these standards, and (3) an assessment of two different analytical approaches to evaluate the performance standards. Our results indicated that all six configurations of reef material and bottom coverage tested provided suitable habitat for kelp forest fishes. Fish standing stock, density, species richness, and recruitment on all the artificial reef designs were either similar to, or greater than, that observed at two nearby natural reefs. The amount, but not the type, of reef material had a substantial influence on the fish assemblage, with higher densities and numbers of species occurring on artificial reef modules with greater coverage of hard substrate.