Fish don't follow international boundaries or understand economic trade agreements. Different species live in regions all over the globe. If that wasn't complicated enough, they also migrate as they age.
"It's like trying to raise cattle when you've taken down all the fences," says Karrigan Bork of the McGeorge School of Law, University of the Pacific, whose background includes a PhD in ecology. "Except you can't even brand the fish. There's no way to know which fish is yours."
And in response to climate change, vital fisheries stocks such as salmon and mackerel are migrating without paperwork.
According to a new study being published yesterday in Science Magazine, coastal countries need to collaborate even more on international fishing regulations to prevent misuse of resources. Food, environmental and economic securities are at stake, it warns.
The study maps out the locations of fisheries and the national jurisdictions that govern them. The researchers' analysis is based on economic, legal, statistical and ecological data, which they used in sophisticated modelling to predict the future of international fisheries and to make recommendations for success.
"This isn't some imaginary future threat," said Malin Pinsky, an assistant professor at Rutgers University, who helped lead researchers at six universities in a half-dozen countries as part of the Nippon Foundation-University of British Columbia Nereus Programme.
Fisheries are critical to food security, jobs and economic stability. As far back as the 1600s, Great Britain and Iceland faced off over rights to the Atlantic cod; they negotiated their claims to the meaty half of fish and chips over the next several centuries. And after World War II, fishery disputes prompted militarised action in democratic countries. Navies were deployed. Protests were staged.
Modern international fishing rights are further complicated as oceans warm because of climate change. According to Angee Doerr, a research scientist who specialises in fisheries at the Stanford Centre for Ocean Solutions, developing countries in tropical areas are particularly at risk. "Equatorial countries are highly dependent on fish as a protein source," she said. As water temperatures increase, "fish are moving to stay within their comfortable range". This means they may be leaving their traditional waters altogether.
But changes in a single fish species do not occur in a vacuum. They affect the entire food web, potentially altering the ecosystem for all species once one is affected. With increasing technology and computer modelling, however, scientists are getting closer to understanding what our future oceans may look like.
Pinsky and his colleagues analysed 892 species of commercially important fish. They also examined 261 "Exclusive Economic Zones" - areas of the ocean where countries have jurisdiction under international law. Using this data plus complex climate models, which incorporated ocean temperature, currents and oxygen levels and other factors, the scientists created a map of global fisheries projections. They outlined the likelihood of specific stocks moving into new economic zones, depending on various climate scenarios.
The study, which reflects an unusual combination of expertise from law, policy, economics, oceanography and ecology, suggests multispecies movement across dozens of countries' waters. On average, it says, fish are venturing into new territories at 69km per decade, a pace expected to continue and accelerate.
Challenges will only increase, according to the researchers. One reason is that policymakers often move more slowly than the fish. The study identifies gaps in current international regulations for global fisheries, with the researchers expressing concern that limited attention is being paid to the cascading effect on the food chain.
Bork agreed that the issues around global fish stocks are increasingly interdisciplinary and need scientists and lawmakers working together to address them.
Neither he nor Doerr were involved in the new study.
Conflicts can arise from just one new species entering a nation's waters, which suggests the potential for big problems in the future. The study predicts that areas with unclear international jurisdiction will be targets for conflict.
Just this week in the South China Sea, fishing rights are being contested by Filipino officials, who say the Chinese coast guard is confiscating fish catches in disputed areas.
But if fish stocks migrate to a new country before management is in place, there may be a period when the fish are literally lawless, meaning not governed by any entity.
"A fishery that's shared for the first time is like two kids facing off for the last piece of cake. They'll race to grab it and get cake smeared all over the table," Pinsky said.