Study: Tunas, sharks ‘seriously exploited’
Populations of tunas, sharks, marlins and swordfish are in dire straits, according to a new study from the University of British Columbia’s (UBC) Fisheries Centre.
Funded by the Pew Charitable Trusts, the Natural Sciences and Engineering Research Council of Canada and the French Consulate-General in Vancouver, UBC researchers modeled the impact of fishing around the world using global landings databases from 1950 to 2006 and satellite images of phytoplankton, which are used to map where predators should be, based on food availability.
The researchers found that, in half of the North Atlantic and North Pacific waters under national jurisdiction, fishing has led to a 90 percent decline in top predators such as sharks and tunas since the 1950s.
“Species such as tuna have been seriously exploited because of high market demand,” says Laura Tremblay-Boyer, a PhD student at UBC Fisheries Centre and the study’s lead author of the study. “A constant theme throughout our study of global marine ecosystems is that these top predators are today prey for human beings, assisted by some serious technology. Top marine predators are more intrinsically vulnerable to the effects of fishing due to their life histories. Bluefin tuna, for instance, cannot reproduce until age nine.”