Global Fisheries Face Dramatic Decline in Productivity

University of California Irvine (UCI) climatologists say unbridled global warming is expected to result in dramatic declines in the productivity in global fisheries by 2300.

The world’s fisheries, on average, will be 20 percent less productive, those in much of the western Pacific will see declines of more than 50 percent, and those in the North Atlantic will be down nearly 60 percent, according to the UCI study published in Science in early March.

“There is still time to avoid most of this warming and get to a stable climate by the end of this century, but in order to do that, we have to aggressively reduce our fossil fuel and emissions of greenhouse gas pollutants,” said J. Keith Moore, a UCI professor of Earth system science, and lead author of the study.

The study presents the results of computer simulations showing a world subjected to nearly three more centuries of global warming, characterized by a 9.6 degree Celsius (17 degrees Fahrenheit) increase in mean surface air temperature, nearly 10 times the warming seen to this point. This warming will drastically alter wind patterns, boost ocean surface temperatures and melt nearly all sea ice in polar regions.

“These conditions will cause changes in phytoplankton growth and ocean circulation around Antarctica, with the net effect of transferring nutrients from the upper ocean to the deep ocean,” said Moore. “Marine ecosystems everywhere to the north will be increasingly starved for nutrients, leading to less primary production (photosynthesis) by phytoplankton, which form the base of ocean food chains.”

In today’s oceans, nutrients are brought up to the surface around Antarctica, then move north and eventually flow into the low latitudes, supporting plankton and fish populations there, Moore explained. With increased phytoplankton growth around Antarctica, the northward transfer of nutrients will be greatly reduced.

“You end up trapping the nutrients near Antarctica,” he said.

“By looking at the decline in fish food over time, we can estimate how much our total potential fisheries catch could be reduced,” he added.

Read the full paper at