Reduced fish diversity despite increased fish biomass in a Gulf of California Marine Protected Area

A study of the Islands and Protected Areas of the Gulf of California reveals that while fish biomass has increased in a Marine Protected Area (MPA), fish diversity has declined. This counterintuitive finding suggests that moderate fishing pressure, despite being less intensive than commercial fishing, still hampers biodiversity conservation. Researchers used traditional and functional metrics to analyze fish assemblages from 2005 to 2017 at Espíritu Santo Island, Mexico, comparing sustainable fishing, traditional fishing, and no-take zones. They found declines in species and functional richness, indicating potential risks of local extinction and loss of ecosystem processes. The increase in biomass was linked to larger average fish sizes rather than commercial species, highlighting the need for stricter enforcement of fishing regulations and expansion of no-take areas to preserve functional diversity.

Ramírez-Ortiz, G., Reyes-Bonilla, H., Balart, E. F., Olivier, D., Huato-Soberanis, L., Micheli, F., & Edgar, G. J. (2020). Reduced fish diversity despite increased fish biomass in a Gulf of California Marine Protected Area. PeerJ, 8, e8885. Portico. https://doi.org/10.7717/peerj.8885