The oceans ain't what they used to be, say researchers
By analyzing sport fishing photos, dated from 156 to 2007, from the Key West area near Florida, researchers found that the average fish size dropped from about 23 kilograms to only 2.3 kilograms. (AP / Jeff Barnard) |
Only decades before the factories of the industrial revolution sullied Europe's skies with smog in the 19th Century, coastal Great Britain teemed with marine wildlife like dolphins, orcas and blue whales, according to a new study.
Seven seas away, during the early 1800s, the waters surrounding New Zealand were home to nearly 30,000 southern right whales, which researches say is about 30 times today's population.
Those historical sketches are just some of the findings to be showcased during the Census of Marine Life conference, which takes place in Vancouver from May 26 - 28.
While the contention that today's oceans are less populated than they used to be isn't new -- school kids are taught that John Cabot's crew caught fish in Newfoundland with only a basket -- the experts behind the data say their findings are important in terms of perception and conservation.
According to University of New Hampshire researcher Andy Rosenberg, recent observations of the world's waterways have skewed perceptions about the health of our rivers, lakes and oceans.
Rosenberg, a top researcher for the Census' History of Marine Animal Population (HMAP) project, also says the historical findings are forcing officials to confront current preservation efforts.
One key region for researchers has been New Zealand, which is among the most recently populated places on earth.
While much of Eurasia and Africa have been heavily populated for thousands of years, New Zealand was first settled by pacific islanders around 1280 A.D., which gives researchers a clearer picture of human impact on marine life.
HMAP researchers analyzed more than 150 whaling logbooks and found that right whale population near New Zealand in the early 1800s was between 22,000 and 32,000.
However, by 1925, there were only 25 female whales capable of producing offspring, the researchers say. The findings are 95 per cent accurate, according to HMAP.
Today, about 1,000 of the whales are being closely monitored by researchers and the HMAP data is already being used to guide conservation efforts.
"These findings point up the need to re-examine the role southern right whales once played both as a grazer of zooplankton and prey, especially during calving close inshore, for killer whales and great white sharks," said Alison MacDiarmid, a conservationist employed by the New Zealand government.
Arguably, one of the most important findings is how much oceans have changed in the past few decades.
By analyzing sport fishing photos, dated from 1956 to 2007, from the Key West area near Florida, researchers found that the average fish size dropped from about 23 kilograms to only 2.3 kilograms.
The census team also found that big predators like sharks often dominated the early trophy photos. These days, however, small fish like snappers are the norm.
According to leading researchers, the findings are new and important to the overall health of the world's waters.
"Most histories of successful marine recoveries are found among mammals and birds, but cases involving marine reptiles and fish also exist. Only in a few cases, however, did they fully recover their former abundance," according to Dalhousie University researcher Heike Lotze.
"In the past, some combination of reduced or banned exploitation, pollution controls or habitat protection, especially of breeding colonies and feeding grounds, propelled recovery."(Source:Jered Stuffco, CTV.ca News)
