July 28, 2016 — Overfishing is a known culprit of the decline of Atlantic cod off the coast of New England but now, a new study co-authored by researchers at UC Santa Barbara and Columbia University has found that the climatological phenomenon known as the North Atlantic Oscillation (NAO) is also a factor. And it contributes in a predictable way that may enable fishery managers to protect cod stocks from future collapse.
“In the 1980s, the North Atlantic was stuck in a positive phase of NAO,” said lead author Kyle Meng, an economist at UCSB’s Bren School of Environmental Science & Management.
“We show not only that positive NAO conditions diminish a few consecutive cohorts of cod larvae but also that this effect follows a cohort as it matures.”
The NAO is a periodic climatic phenomenon that, like El Niño, causes changes in water temperatures, although the mechanism is different and the NAO affects the North Atlantic rather than the Pacific.
Also like El Niño, the NAO may be affected in terms of both strength and frequency by climate change. The researchers found that, since 1980, NAO conditions have accounted for up to 17 per cent of the decline in New England cod stocks.
“The Atlantic cod fishery has been the poster child of fishery science and challenges in the field,” said co-author Kimberly Oremus of Columbia University’s School of International and Public Affairs.