Overfishing even harms marine protected areas
Marine protected areas appear to be havens for the fish that inhabit them, but a new study from Tel Aviv University shows that this is only the case for those fortunate enough to reside in the center of them, not around their edges.
The study, conducted by doctoral student Sarah Ohayon and recently published in Ecology and evolution of nature, shows that overfishing at the borders of marine protected areas (MPAs) leads to a sharp reduction in the fish population on their edges, reducing the efficiency of the entire area.
This “edge effect” can reach up to 1.5 kilometers (1 mile) inside the AMP. It has already been studied in terrestrial but not marine protected areas.
“This phenomenon occurs when there are disturbances and human pressures around the MPA, such as hunting / fishing, noise or light pollution which reduce the size of natural populations within MPAs near their borders” , explains Ohayon.
She conducted a meta-analysis that included spatial data on the marine populations of dozens of MPAs in different oceans.
The study showed that 40 percent of the world’s “no-take” MPAs (areas where fishing activity is prohibited) are less than one square kilometer, which means that the entire MPA is susceptible. to undergo a border effect.
Additionally, 64% of all non-harvest MPAs are less than 10 square kilometers in area and may only contain about half of the expected population in their area compared to a no-edge situation.
These results indicate that the effectiveness of existing non-harvesting MPAs is much lower than previously thought.
The research also showed that no edge effect patterns were recorded in MPAs with buffer zones, and a smaller edge effect was observed in well-applied MPAs compared to those where illegal fishing. has been reported.
“When planning new MPAs, in addition to establishing regulated buffer zones, we recommend that non-harvest MPAs targeted for protection be at least 10 km away.2 and as round as possible, ”concluded Ohayon. “The results of our research provide practical guidelines for improving the planning and management of MPAs, so that we can better protect our oceans. “