The number of fish caught in a marine protected area in Hawaii has seen an increase in recent years, indicating that the expansion of the reserve in 2016 may have supported the fish populations in the area.
When President Barack Obama quadrupled the size of the Marine National Monument in Papahānaumokuākeanow at 1,510,000 square kilometers, marine conservationists around the world have rejoiced.
Fishermen did not participate in the festivities as fishing is prohibited in this protected area. Defenders of the reserve have argued, however, that creating space for the recovery of declining tuna populations would also benefit fishing.
In fact, according to them, if the populations within the boundaries of the reserve were to increase continuously, the fish would necessarily spread to the surrounding areas, thus increasing the amount of tuna available for fishing.
However, as tuna cannot be directly counted and their numbers can fluctuate for various reasons other than stock expansion, it is difficult to prove this. But a new study published this week in the magazine Sciencesuggests, based on data collected between early 2010 and late 2019, that the number of fish caught very close to the protected area is higher today than a few years ago.
Alan Friedlander, chief scientist of the National Geographic Society Pristine Seas Projectcalls the study “a very rigorous test of the effects of marine protected areas”.
“This is one of the few studies to show the real benefits of relapse [de ces mesures], which are often difficult to prove. This is great news, as it offers a solid approach that we can use to assess and improve protected areas in other parts of the world. “
A FAVORABLE ECONOMY
According to John Lynham, an environmental economist at the University of Hawaii who participated in the writing of the study, it is important to specify that the increase in the number of tuna caught near the reserve is also observed in the average number of catches of each fisherman. This element indicates that the effect is not due to new, more efficient crews that would have arrived in these waters in the meantime, he explains. To allow for a more accurate assessment, the numbers taken were divided by the increasing number of hooks cast in these waters.
“There are about 150 fishing boats in Hawaii that drop between 40 and 50 million hooks a year,” explains the economist. “To maintain a high catch rate, fishermen are constantly adding more. “
Hawaii-based vessels account for about two-thirds of the region’s fisheries. “Some boats come from Japan, China and Taiwan, but we don’t have access to detailed data on what they catch,” she said.
Based on catches reported by fishing vessels and marine biologists at the US Oceanic and Atmospheric Observation Agency, Lynham and her colleagues found that hook and line catches increased over the ten-year study. On average, between 2010 and 2019, the team calculated that for every 10,000 hooks, fishermen caught 6 more yellowfin and 5 bigeye tuna a year since the area expanded.
“The latter particularly surprised us because it is much more economically important and because fewer data points to an increase,” says Lynham.