March 11, 2014 — Warming oceans aren’t just shifting the migration patterns of some of our favorite fish; scientists say climate change may be stunting fish sizes too.
Widely consumed North Sea species, including haddock, whiting, herring, and others, have shrunk in size by as much as 29 percent over nearly 40 years, as water temperatures have increased between one and two degrees Celsius, researchers from the University of Aberdeen in Aberdeen, Scotland, revealed in a study published in the April issue of Global Change Biology.
Intense fishing pressure or low food supply may also contribute to smaller fish, but lead author Dr. Alan Baudron says concurrent size declines in different schools of fish points to climate change as a smoking gun.
“What is interesting is this was detected across a range of fish species eating different diets, living at different depths, and experiencing different levels of fishing mortality,” said Baudron. “The synchronicity suggests that the one common factor they all experienced—increasing water temperatures—could have been at least partly responsible for the observed reductions in length.”
Baudron and his team analyzed age and length data—collected by the International Councils for the Exploration of the Sea—from commercial fish caught between 1970 and 2008.
Not all species experienced a decline in size. Cod sizes were not affected, and female sole only shrank by 1 percent. Exactly why is unclear.
“Disentangling the effects of these factors can be extremely difficult,” Baudron said.
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