Climate Change Already Causing Fisheries Collapse

Written by on October 19, 2012 in Marine Life, Physical Oceanography
Climate change is causing sardine populations near Venezuela to plummet. Photo credit: SWFSC/NOAA.

Climate change is causing sardine populations near Venezuela to plummet. Photo credit: SWFSC/NOAA.

A new study determined that climate change caused the collapse of a fishery in Venezuela, showing that even small increases in temperature are harming ocean life.

This study was conducted over a 15-year period, during which researchers from University of Southern California, Stony Brook University, University of South Florida and several Venezuelan institutions collected data regarding nutrient and chlorophyll concentrations, meteorological readings, and many other variables at a single point off the coast of Venezuela.

Throughout this period, the temperature only increased about 1 degree Celsius, but the population of many microscopic organisms, and the local sardine harvest plummeted consistently, beginning in 2006.

Robert Thunell, co-author from USC, explained the reason for the decline:

  • The “thermal equator” is the area just north of the geographic equator where the northeast and southeast trade winds meet
  • The location of the thermal equator causes the northern hemisphere to heat faster than the southern hemisphere
  • This uneven heating due to global warming causes the thermal equator to shift farther northward
  • The shift causes the trade winds to decrease in the southern Caribbean, where Thunell and colleagues have been collecting data for over a decade
  • Less wind means less mixing of the oceans
  • Less mixing means a diminished food supply for phytoplankton
  • Decrease in phytoplankton causes a decrease in fish populations

“That’s a big deal.  The plankton near the surface of the ocean are the base of the food chain,” said Thunell.  “This climatological change is driving a change in the food web structure, which we’re now seeing affect the fisheries.”

Islas Los Roques, a Venezuelan National Park known for its beautiful reefs and marine diversity, located in the Caribbean Sea. Photo credit Juan Valero.

Islas Los Roques, a Venezuelan National Park known for its beautiful reefs and marine diversity, located in the Caribbean Sea. Photo credit Juan Valero.

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Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of MarineScienceToday.com. She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .

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