CELS Researcher: Fisheries Outcomes Maximized Through Traditional Practice

A spearfisherman in the Solomon Islands, where periodic fisheries closures are commonly used for marine resource management. (Photo by Crow White/CalPoly)

A new study led by a University of Rhode Island doctoral student and published in the Journal of Applied Ecology has found a possible solution to one of the biggest conservation and livelihood challenges in the marine realm.

Paul Carvalho, along with URI Assistant Professor Austin Humphries and colleagues from several other institutions, found that fishing grounds with areas that are closed to fisheries but are periodically harvested are better than fishing grounds with permanent, no-take marine protected areas.

Further, they found that such “pulse” harvest marine protected areas also perform better than traditional measures that aim to keep fisheries at maximum sustainable yield.

Carvalho said that this study could help revolutionize fisheries management and settle a long-running debate between fisheries management and conservation sectors about the role of marine protected areas in balancing potential for stock recovery and maintaining yields.

“We were impressed by how well periodic closures continued to perform under different scenarios,” said Carvalho, who conducted the research while studying at California Polytechnic State University. “Across a large range of closure durations, closure sizes, fish population growth rates and movement patterns, fishing grounds with periodic closures consistently gave the best combined outcomes for stock, yield and catch efficiency.”

At the crux of the matter is the current model of fishing closures. Conservationists have argued that permanently closed, no-take marine protected areas are an effective means of mediating overfishing and allowing stock replenishment, and many global conservation agencies are thus calling on high levels of protection in 30 percent of the world’s oceans.

However, marine protected areas can shift fishing effort into remaining fishing grounds. More crowded fishing grounds can make it harder to find fish, thus reducing catch efficiency and driving up costs for the industry to maintain steady yields. Fisheries managers have long championed tools such as quotas and access restrictions—the second management strategy to prevent overfishing and let fish populations rebuild—to try to maintain sustainable catches. But global declines in fish stocks have called into question whether these measures on their own are effective enough. Therein lies a tradeoff, where managers seemingly need to balance competing objectives for keeping fish in the sea and fish on the dinner plate…[Read more]