The “sustainable” fishing industry has a dirty secret, according to new research presented at a conference in San Francisco, Calif.
“Sustainable” fishing programs which ban the use of purse seining, or dragnets, actually use three times as much fuel now as they did 25 years ago, doctoral student Brandi McKuin with the University of California, Merced told the New Scientist.
Fishing ships now must use methods like “troll and pole line fishing or longline fishing” that are comparatively less efficient than dragnets, according to the New Scientist. The methods indicated result in lower catch tallies per fishing trip, meaning that fishing boats must use more fuel and make more trips to increase their catches.
Extra trips use more fuel and consequently, produce more black carbon emissions. “Black carbon” is a pollutant and a large component of soot. Fine particles found in black carbon also absorb light, which McKuin says exacerbates global warming.
“If we’re including climate change in the sustainability criteria, it changes things,” McKuin told the New Scientist, referring to her study on global warming emissions from sustainable fishing.
McKuin’s study also “suggests that short-lived climate forcing may be particularly important in regions where fuel has a low sulfur content.” Sulfur is an aerosol emitted from fuel that reflects incoming light and can actually have a cooling effect on the climate.
Sulfur is also a pollutant, so environmental regulators in Europe, the U.S. and other developed countries have rules limited how much of it can be in fuel. McKuin’s work suggests a possible unintended consequence of limiting inclusion of sulfur in fuel is potentially more warming.
“These results have implications for proposed maritime policies and provide a foundation for future climate simulations to forecast climate change impacts in the Arctic,” McKuin wrote in her study.
McKuin also found that sustainable-caught tuna had more of a warming effect than any other land-based source of protein, except beef. Raising livestock is allegedly a major source of methane emissions.
“Sustainable” programs may prevent over-fishing, but the unintended consequence is more pollution and maybe more global warming, if McKuin’s findings are accurate.