Study finds global fisheries shrinking due to climate change, overfishing

The effects of climate change have been well proven in areas like weather patterns and animal habitats, but a new study highlights how the same problems are found in our oceans, with rising sea temperatures having a significant impact on the world's fisheries. Led by Rutgers, the research shows that critical fisheries have seen at least a 4% drop in populations since 1930, with certain areas experiencing as much as a 35% decline.

Fisheries are what the fishing industry calls regional groups of fish populations that can be economically farmed. They are essential not only to the over 56 million workers in the fishing industry worldwide, but they also provide essential nourishment to parts of the world dependent on seafood, such as developing countries in coastal regions.

The study, which has just been published in the journal Science, was conducted by scientists combining the data on global fishery populations with maps of rising ocean temperatures from 1930 to 2010, in turn understanding the effects of temperature changes on sustainable catches. "We were stunned to find that fisheries around the world have already responded to ocean warming," said study co-author and Rutgers associate professor Malin Pinsky. "These aren't hypothetical changes sometime in the future."

Overall the scientists found a 4.1% decline in sustainable catches on average, with the worst areas being five regions that include the Sea of Japan/East China Sea and North Sea, where fisheries experienced losses between 15% and 35%. Magnifying these results are overfishing, which not only makes regional species more vulnerable to rising temperatures, but also makes it significantly harder for fisheries to rebuild populations alongside ocean warming.

Interestingly, the researchers also identified several fish species that have benefited from temperature changes, such as areas in Labrador-Newfoundland, Baltic Sea, and Indian Ocean. However, these gains are far outnumbered by the declining populations. "Fish populations can only tolerate so much warming, though," noted senior author Olaf Jensen of Rutgers' Department of Marine and Coastal Sciences. "Many of the species that have benefited from warming so far are likely to start declining as temperatures continue to rise."

The study emphasizes the point that its quantified data represents changes that have already taken place within global fisheries, and isn't hypothetical estimates of what could take place in the future. Along with suggesting that fisheries managers work to eliminate overfishing and focus on rebuilding populations, the researchers noted that ongoing regional disparities could be addressed with "trade agreements and partnerships to share seafood between winning and losing regions."