Well over half of the world’s marine protected areas are failing to do the job for which they were created, mainly due to illegal overfishing, a Tel Aviv University study shows.
Marine protected areas, or MPAs, are designed to protect marine ecosystems and help to conserve and restore fish populations and marine invertebrates whose numbers are increasingly dwindling due to overfishing.
When an MPA functions properly, marine stocks within it are supposed to not only recover within the protected area, but to spill over and migrate beyond it, strengthening numbers immediately outside of the MPA as well.
The effectiveness of MPAs has been proven in thousands of studies conducted worldwide. But most have sampled only the “inside” and “outside” of the MPAs, with little research into the areas in between.
Doctoral students Sarah Ohayon and Itai Granot combined estimates of the numbers of fish and invertebrates belonging to 72 taxonomical groups, with their spatial distributions across 27 MPAs in different parts of the world where fishing is banned.
Under the supervision of Prof. Yoni Belmaker of Tel Aviv University’s Zoology Department and Steinhardt Museum of Natural History, the two found that “there is a prominent and consistent edge effect that extends approximately 1 kilometer (0.62 miles) within the MPA, in which [fish] population sizes…are 60 percent smaller than those in the core area,” mainly because of fishing.
MPAs that are smaller than ten square kilometers, or 6.2 square miles — and these account for 64% of all ‘no-take’ MPAs in the world, where fishing is totally banned — “may hold only about half (45-56%) of the fish population” that is commonly assumed, the researchers wrote recently in Nature Ecology and Evolution.
Some 40% of MPAs are just one square kilometer, which means that the entire area probably experiences this edge effect, they added.
The findings, the researchers concluded, indicate that the “global effectiveness of existing no-take MPAs is far less than previously thought.”
No edge effects were found in MPAs which had no-fishing buffer zones created around them and there were less of these effects where there were no buffer zones, but bans against fishing were enforced.
“These findings are encouraging,” the researchers said, “as they signify that by putting buffer zones in place, managing fishing activity around MPAs and improving enforcement, we can increase the effectiveness of the existing MPAs and most probably also increase the benefits they can provide through fish spillover.”
In Israel, much hope is being pinned on the series of marine nature reserves along Israel’s northern coast, where six surveys have been carried out under the direction of the Israel Nature and Parks Authority since 2015, the most recent in 2019.
These have found that since a fisheries reform in 2016 and the creation of a marine enforcement unit within the INPA in 2018, commercial fish numbers in the Achziv-Rosh HaNikra Reserve, in northern Israel, the largest and oldest, have grown to three times more than those outside of the reserve. The number of groupers — which are commercially important but also sensitive to fishing — was four times greater than those outside, and their biomass (living material) was eight times greater.
Grouper numbers increased in all marine reserves, as well as outside of them, suggesting — the scientists said — that both the existence of the reserves and the enforcement of fishing bans during the breeding season were having a positive effect.
Out of the breeding season, groupers within the reserves were able to grow well, produce more offspring, and better resist disease and parasites, the research suggested.
Yigal Ben-Ari, the INPA’s head of marine enforcement, told The Times of Israel that he “senses” stabilization, even slight improvement, along Israel’s stretch of the Mediterranean Sea.
The 2016 reform banned certain types of fishing, determined minimum sizes of fish that can be caught (to give juveniles the chance to reach sexual maturity and reproduce), set the sizes for the holes in nets, empowered a chief fishery officer to issue bans on fishing during the breeding and recruitment (a stage of juvenile fish growth) seasons and gave the INPA responsibility for enforcement.
That enforcement unit, now in its third year, has already opened 1,300 files on violations and taken some NIS 2 million ($615,000) in fines. Fines start at NIS 750 ($230). Just a week ago, the unit confiscated a fishing boat and fined the owner NIS 8,000 ($2,465) and a further NIS 20,000 ($6,160) if the regulations are violated again.
Dr. Nir Stern, who started monitoring fish populations at the country’s Oceanographic and Limnological Research Institute in 2014, said there was no real data from before the fisheries reform that could be used to assess whether overfishing had taken place.
His research is showing ups and downs in different fish populations, he said, adding that it is too early to connect any trends with the 2016 reform and the enforcement unit.
“People who dive say they’re seeing more fish than usual,” he said. “I think the sea is recovering, but it takes time.”
Ben-Ari stressed that most recreational and commercial fishermen obeyed the law and shared the INPA’s interests in maintaining healthy seas.
But with 12 inspectors responsible for the 190 km (118 mile) Mediterranean coast, one for Eilat’s 14 km (8.7 mile) coast (and one for the Sea of Galilee, a lake), the unit is stretched.