Take Two for March 26, 2013

Study: Global warming may shrink fish size

PALESTINIAN-DAILYLIFE-FISHING

MOHAMMED ABED/AFP/Getty Images

Palestinian fisherwoman shows the fish on sale along the sea front in the Deir al-Balah Palestinian refugee camp, central of Gaza Strip, on September 18, 2012.

They say it's better to be a big fish in a small pond, but a new study shows that being a 'big fish' may be harder in the future.

Scientists believe that, because of warming ocean temperatures, fish may have trouble growing large and the world may end up with more small fish in the water. According to a study published in the journal Nature Climate Change, hundreds of species of fish could see their body mass percentages dwindle by 14-24 percent between the years 2000 and 2050. Fish in tropical climates could see an average body mass decrease of 20 percent.  

"One of the rare but universal principles in biology that seems to affect almost all living things is that the warmer the temperatures that bodies develop at, the smaller they end up," said marine biologist Pat Krug on Take Two. " So what scientists have found is that everything from bacteria to plants to fish to seaweeds show this trend where when temperatures are warmer, they grow smaller."

The authors of the study looked at 600 different species of fish and found that larger-bodied fish were most strongly affected by this phenomenon. Overfishing and pollution could exacerbate the problem further. 

"A medium-0sized fish would lose about 5 percent of its body mass for every degree centigrade that the water was warmer. So the difference of a few degrees would make a huge difference in terms of the body mass at which these fish would stop growing," said Krug. "The bigger you are typically the more eggs you can produce and often the larger and healthier the offspring you can produce are, so there is definitely some negative synergy going on in terms of how body size can constrain the  health of a population, a species and an ecosystem."

The affect these body mass changes will have on the seafood industry is difficult to predict, but Krug says it's safe to assume it would have a negative impact. 

"There's certainly going to be economic as well as ecological impacts of this, but it's something that up until now hasn't even been factored into these models," said Krug. 


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