Article by: Nur Hidayahanum Hamid

Source: Smithsonian

Marine protected areas (MPAs) are intended to rebuild fish populations, but many fail to do so effectively. A study published in Global Change Biology on April 4 analyzed the age breakdown of reef fish in MPAs and found that adult fish populations in most areas have either flatlined or declined. Adult fish are crucial for breeding and supporting fisheries, as larger and older females produce more and better eggs. This study is significant as the world aims to protect 30% of the ocean by 2030, a goal set at the United Nations Biodiversity Conference in December 2022.

The study focused on the Mesoamerican Reef, the longest reef in the Western Hemisphere, spanning over 600 miles and home to diverse marine life. Researchers examined fish biomass in 139 reef sites, both protected and unprotected. Protected sites were categorized into fully protected areas, highly protected areas, and general use zones. Only 24% of the protected sites fell into the fully or highly protected categories.

Results showed that only 11 sites (8% of the total) saw significant increases in adult biomass. Most sites saw no change or declines, especially those with heavy coastal development and warming waters, and inadequate enforcement. In contrast, the sites with rebounding adult populations had strong enforcement, less climate impact, and lower human footprint.

The study highlights the importance of strong enforcement and effective management for MPAs. It also emphasizes the need to consider climate refuges and community support when selecting new sites for protection. Understanding the different responses of adult and juvenile fish to environmental changes is crucial for maximizing the benefits of MPAs and achieving global conservation targets.

Picture 1: Bluestriped grunts and gray snapper, two fish species vital to the local economy, in Belize's Hol Chan Marine Reserve (Credit: Pete Oxford/iLCP)

Picture 2: Bluestriped grunts swim around a reef in Hol Chan Marine Reserve, Belize (Credit: Luciano Candisani /iLCP)

Date of Input: 29/05/2024 | Updated: 07/06/2024 | hidayahanum