Reef Fish Crowding Effects Vary Across Species and Contexts

This meta-analysis of 38 reef fish species across 56 studies shows that density-dependent mortality varies substantially both within and among species, changing how scientists think about fish population regulation. The researchers conducted a broad meta-analysis examining 147 estimates of intraspecific density-dependent mortality from studies of reef fish, primarily during early life stages. The magnitude of density-dependent mortality was inconsistent both within and among species. Predators amplified the negative effects of density on fish survival. Density-dependent mortality was greater for species that typically colonize at low densities or achieve larger maximum sizes. Even within a single species, the strength of density-dependent mortality varied substantially, often by several orders of magnitude, and sometimes changed sign. Understanding population regulation is essential for fisheries management and conservation. The study shows that density dependence does not operate consistently. Environmental context, predator presence, and species traits all shape how fish populations respond to crowding.

Citation

Stier, Adrian C.; Osenberg, Craig W. (2025). Widespread Heterogeneity in Density-Dependent Mortality of Nearshore Fishes. Ecology Letters.

"Even within a single species, the strength of density-dependent mortality varied substantially, often by several orders of magnitude, and sometimes changed sign."