In order to preserve worldwide fish stocks, fisheries around the world will have to curtail their current overfishing. Without sustainability efforts, profitable fish stocks could rapidly deplete, leaving once-booming fisheries with nothing to catch. Over time, reducing global fishing would not only bump up catch hauls and profits, but also help save a number of endangered species that are accidentally caught in nets and on fishing lines.
That’s the conclusion of a new study published in Science that examines the intersection of fisheries sustainability and fishing industry profits, as well as its effect on bycatch. The study was led by marine biologists at the University of California, Santa Barbara. Study co-author Rebecca Lewison, a biologist at San Diego State University, provided expertise on the bycatch of threatened populations of marine mammals, sea turtles and sea birds.
In some ways, the idea that conservation and managing fisheries could go hand-in-hand is a radical notion, Lewison noted.
“Often we think of fisheries management and conservation as being irreconcilable,” she said. “Results from this work, and from other recent fisheries management initiatives, show how measures to promote sustainable fisheries can both support profits and protect threatened and endangered species.”
For the study, researchers analyzed the fishing effort and profits of 4,713 fisheries around the world, accounting for about 75 percent of all fisheries. Given the concerns with dwindling fisheries catches, the team first calculated how much fishing would need to be reduced to maximize profits over time. They then calculated how much fishing would need to be reduced in order for 20 threatened bycatch populations to recover.
Comparing the two, the researchers found that by reducing maximum profit models by less than 5 percent, between seven and 13 bycatch species could be saved. In total, fishing effort around the world would need to be cut in half to reverse declines in most bycatch species, remain profitable and contribute to sustainable fish stocks.
The models do contain a fair amount of uncertainty—Mother Nature is rarely totally predictable—but “even if we’re somewhere in the ballpark with our models, the relationship between recovering fish stocks and protected bycatch species should hold,” Lewison said.
Under this profit-maximizing, bycatch-minimizing plan, some populations would fare better than others. For example, the threatened eastern Pacific leatherback turtle is imperiled by bycatch, but at the same time, overfishing is unsustainable in the region. Convincing local fishermen to reduce their catch in the short-term will result not only in higher longer-term profits, but also will help save the turtle. But saving other species, like the nearly extinct vaquita porpoise in the Gulf of California, would require a near-total stop to fishing in the region, which isn’t a realistic or likely proposition.
The economic demands of fisheries and their impacts on bycatch make for a tricky balancing act. How exactly governments and fisheries might come to an agreement over such a plan wasn’t addressed in this study, but Lewison said the findings represent a rare opportunity to align the efforts of fisheries and conservation.
“What’s exciting about this work is that it focuses attention on the possibility of meeting multiple objectives with a single management action,” she said. “These results suggest that reducing fishing pressure on some stocks can both rebuild fisheries and lead to meaningful population recoveries for species of conservation concern.”