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Caribbean Sardine Collapse Driven By Climate Change, Overfishing, Study Says

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Sardines may be small, but they pack a big punch -- and we're not just talking about in a piping hot bowl of sardine-y Fisherman's Eggs.

As Huffington Post bloggers Lee Crockett and Glen Martin noted earlier this year, small fish like sardines and anchovies, as well as herring, may not get very much appreciation or press, but these tiny creatures are absolutely essential to maintaining the health of many marine ecosystems.

"As well as constituting the basis for idiosyncratic pizzas, sandwiches, and hors d'oeuvres, these three fish are critical forage for a great number of other marine species, including seabirds, whales, seals and sea lions, and valuable food fishes including salmon, lingcod and rockfish," Martin, author of "Game Changer: Animal Rights and the Fate of Africa's Wildlife," wrote last month.

However, according to a recent study, sardines in the Caribbean are facing diminishing numbers.

In the southern Caribbean, writes SciDev.net, sardine fisheries are collapsing and the decline has put the region at risk of serious consequences. Climate change, plankton decline and overfishing have all been cited as major factors behind the drop.

The study, conducted by researchers from the United States and Venezuela, was published in the Proceedings of the National Academies of Science last month.

SciDev.net explains some of the findings:

The sardine, Sardinella aurita, feeds on plankton but since 2005, plankton levels in the Caribbean have reduced significantly, which, coupled with overfishing, may have contributed to the collapse of these fisheries —- which plummeted by as much as 87 per cent, the study says.

The research team said that the decreasing levels of plankton production are the result of a reduction in ocean upwelling, whereby nutrients crucial for plankton production are brought from the sea's floor to the surface. The drop in upwelling has, in turn, been driven by changes in wind patterns and wind strength, themselves driven by global climate change.

The conclusions are based on monthly measurements taken over a period of 14 years in the Cariaco Basin, off the northern coast of Venezuela.

Cesar Lodeiros, a researcher at the Oceanographic Institute of Venezuela, added that the Venezuelan sardine catch "has dropped from about 200 thousand tons in 2004 to less than 40 thousand tons today."

"Global warming isn't occurring uniformly over the Earth's surface -- it's been much greater at the high latitudes in the Northern Hemisphere than it has been for the low latitudes," study co-author Robert Thunell, a University of South Carolina researcher, said, according to Science Daily.

"Because of that, some people have said, 'Well, we're probably not going to see much biotic change at low latitudes,' but we show nicely in this paper that even when the climatological changes are relatively modest, they can have a big impact on the marine ecosystem."

Thunell added that the drop in plankton populations is cause for real alarm.

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

Researchers added, however, that though "rising greenhouse gas emissions" in the last few decades have contributed to climate change, they are as yet unsure as to whether the decline in Caribbean sardines was triggered by man-made climate change specifically (rather than natural climate variation).

Either way, other than impacting the health of local ecosystems, the collapse of sardine populations in the Caribbean may have a serious impact on the economic health of the region.

In a 2009 report entitled "Vulnerability of national economies to the impacts of climate change on fisheries," scientists argued that global warming has "significantly influenced" and increased the economic vulnerability of some nations that are reliant on their fishing industries.

Venezuela was one of the 30 most vulnerable countries listed in the study.

Photo courtesy Flickr/blueberryfiles

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Filed by Dominique Mosbergen
 
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