The purpose of marine protected areas (MPAs) is to facilitate the recovery of fish populations from overfishing, yet a 12-year study has found that fish numbers within Caribbean MPAs have not rebounded. Researchers suggest lax enforcement of marine protection regulations, coastal development, and rising water temperatures could be to blame. The findings were recently published in Global Change Biology.
The snapper at Hol Chan Marine Reserve, Belize. Image Source: Pete Oxford/ILCP
Stretching over 1000 kilometers along the Caribbean coasts of Belize, Guatemala, Honduras, and Mexico, the Mesoamerican Barrier Reef is home to a plethora of wildlife, including over 500 fish species and 65 types of coral.
Over the past few decades, governments of these countries have established numerous marine protected areas with the aim of safeguarding the precious biodiversity of the coral reefs and restoring fish populations depleted by overfishing. These areas may impose fishing bans during certain times of the year, prohibit certain types of fishing gear, or restrict other activities such as tourism and mining.
To assess the effectiveness of these marine protected areas, Steven Canty and colleagues from the Smithsonian Environmental Research Center analyzed changes in fish biomass across 111 protected areas and 28 unprotected areas from 2006 to 2018. As part of the Healthy Reefs Initiative, these data were collected by scuba divers during surveys.
The research team found that during the study period, only 11 marine protected areas showed an increase in adult fish biomass. Meanwhile, the number of adult fish decreased in 28 protected areas, with no change in the remaining protected areas.
The study revealed that in the 11 areas where fish populations rebounded, marine protected area regulations were effectively enforced, and sea surface temperature fluctuations were minimal. Poorly recovering areas often exhibited the opposite, with weak enforcement of protection measures, increased coastal activities, and more frequent temperature anomalies.
"The success of enforcement in some areas plays a significant role," suggested Canty, emphasizing the importance of local communities who depend on fishing to play a greater role in managing marine protected areas, ensuring they are located in areas less affected by climate change and easier to manage.
"There is still much we don't understand about marine protected areas," added Justin Nowakowski, another team member at the Smithsonian Environmental Research Center. "Therefore, being able to review the past and optimize the future layout and management of marine protected areas is crucial."
Related paper: https://doi.org/10.1111/gcb.17257
