Protection outcomes for fish trophic groups across a range of management regimes

• Published in: Marine pollution bulletin 2021-12, Vol.173 (Pt A), p.113010-113010, Article 113010
• Main Authors: Osuka, Kennedy E., Stewart, Bryce D., Samoilys, Melita A., Roche, Ronan C., Turner, John, McClean, Colin
• Format: Article
• Language: English
• Subjects: Animals; Anthropogenic Effects; Anthropogenic factors; Biomass; Compliance; Conservation of Natural Resources; Coral Reefs; Ecosystem; Fish; Fish biomass; Fisheries; Fishes; Fishing effects; Herbivores; Human population density; Human populations; Humans; Marine invertebrates; Marine parks; Marine protected areas; Piscivores; Population density; Protected areas; Protection; Relative abundance; Restoration; Size-spectra; Spectra
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.113010

Understanding how Marine Protected Areas (MPAs) improve conservation outcomes across anthropogenic pressures can improve the benefits derived from them. Effects of protection for coral reefs in the western and central Indian Ocean were assessed using size-spectra analysis of fish and the relationships of trophic group biomass with human population density. Length-spectra relationships quantifying the relative abundance of small and large fish (slope) and overall productivity of the system (intercept) showed inconsistent patterns with MPA protection. The results suggest that both the slopes and intercepts were significantly higher in highly and well-protected MPAs. This indicates that effective MPAs are more productive and support higher abundances of smaller fish, relative to moderately protected MPAs. Trophic group biomass spanning piscivores and herbivores, decreased with increasing human density implying restoration of fish functional structure is needed. This would require addressing fisher needs and supporting effective MPA management to secure ecosystem benefits for coastal communities. [Display omitted] •Fish size spectra slopes differ with level of protection for coral reef areas.•Fish productivity in highly and well protected areas is greater than fished areas.•No apparent benefits of moderately protected areas.•Significant biomass reduction with increasing human density across trophic groups.•Reducing fisheries impacts and supporting MPAs is critical in densely populated areas.