Relating fish populations to coral colony size and complexity.

A goal of coral reef management is to provide habitat and nursery areas for fish populations. This requires simple and reliable methods for characterizing biological and physical reef features that contribute to fish habitat. Most attempts to establish this relationship have been performed on small-scale, site-specific study areas where variability in fish populations and reef structure is limited and results may be insufficiently robust for extrapolation beyond those sites. Most studies also include geological structures, like ridges and rock formations that provide fish habitat but are not amenable to management action. A focus on the role of Scleractinia (stony corals) may better inform decisions aimed at improving fish habitat. Stony corals provide the structural foundation of coral reefs and are the target of numerous management actions. Data from three broad-area, multi-station reef surveys of fish and stony coral colonies were examined to identify correlations between fish population measures (density, taxa richness and biomass) and both biological (taxa richness and live surface area) and physical (number, size and structural complexity) attributes of scleractinian coral populations. Strongest correlations were found with physical coral features, particularly coral colony height. Characterizing this relationship will improve fishery management tools and support status and trend assessment of the worldwide decline in the physical stature of reefs.