Modeling Reef Fish Biomass, Recovery Potential, and Management Priorities in the Western Indian Ocean

• Published in: PloS one Vol. 11; no. 5; p. e0154585
• Main Authors: McClanahan, Timothy R., Maina, Joseph M., Graham, Nicholas A. J., Jones, Kendall R.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 05.05.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Biodiversity; Biology and Life Sciences; Biomass; Collaboration; Conservation; Conservation areas; Conservation of Natural Resources; Coral reef ecosystems; Coral Reefs; Earth Sciences; Ecology and Environmental Sciences; Economic conditions; Ecosystem services; Ecosystem stability; Environmental aspects; Fish; Fish conservation; Fisheries; Fisheries management; Fishery conservation; Fishery management; Fishing; Fishing (Recreation); Human populations; Indian Ocean; Management; Marine biology; Marine ecosystems; Models, Biological; Oceans; Recovery (Medical); Recovery time; Reef fish; Reefs; Spatial distribution; Studies; Sustainability; Sustainable fisheries; Sustainable yield; Indian Ocean; Queensland Australia; Australia; Kenya; St Lucia; Western Indian Ocean
• DOI: 10.1371/journal.pone.0154585
• ISSN: 1932-6203

Fish biomass is a primary driver of coral reef ecosystem services and has high sensitivity to human disturbances, particularly fishing. Estimates of fish biomass, their spatial distribution, and recovery potential are important for evaluating reef status and crucial for setting management targets. Here we modeled fish biomass estimates across all reefs of the western Indian Ocean using key variables that predicted the empirical data collected from 337 sites. These variables were used to create biomass and recovery time maps to prioritize spatially explicit conservation actions. The resultant fish biomass map showed high variability ranging from ~15 to 2900 kg/ha, primarily driven by human populations, distance to markets, and fisheries management restrictions. Lastly, we assembled data based on the age of fisheries closures and showed that biomass takes ~ 25 years to recover to typical equilibrium values of ~1200 kg/ha. The recovery times to biomass levels for sustainable fishing yields, maximum diversity, and ecosystem stability or conservation targets once fishing is suspended was modeled to estimate temporal costs of restrictions. The mean time to recovery for the whole region to the conservation target was 8.1(± 3SD) years, while recovery to sustainable fishing thresholds was between 0.5 and 4 years, but with high spatial variation. Recovery prioritization scenario models included one where local governance prioritized recovery of degraded reefs and two that prioritized minimizing recovery time, where countries either operated independently or collaborated. The regional collaboration scenario selected remote areas for conservation with uneven national responsibilities and spatial coverage, which could undermine collaboration. There is the potential to achieve sustainable fisheries within a decade by promoting these pathways according to their social-ecological suitability.