Europe’s most fished species ‘will be fractionally reduced’ by 2100
More than a quarter of Europe’s 20 most fished marine species will be reduced in number by the next century if climate change and overfishing continue to threaten their existence, Canadian researchers have warned.
Species – including scallops, mullet and octopus – could be ‘reduced to a fraction’ if not enough is done to address these, according to a new study from the University of British Columbia (UBC). problems as well as mercury contamination.
The three threats “work synergistically to create an unfavorable environment for fish,” said Dr. Vicky Lam, one of the study’s co-authors.
The study is one of the first to examine the combined effects of rising sea temperatures, overfishing and mercury pollution on fish in waters around the European Union.
The study’s lead author, Dr Ibrahim Issifu, a postdoctoral researcher at UBC’s Institute of Oceans and Fisheries (IOF), said popular fish purchased in the EU – such as the large scallop , red mullet and common octopus – “will be weakened by the assault combination” of threats.
“The population of these species will be reduced to a fraction of their current size by the end of the century,” he added.
The researchers selected the 20 fish species that have the highest average annual total catches and revenues in the EU, and determined the temperature tolerance range for each of the species using previous estimates of their environmental conditions. favorite water.
The authors then compared this range with temperature increases that were previously projected for EU waters up to 2100 under high and low carbon emission scenarios.
Finally, different levels of mercury concentrations, as well as unsustainable fishing rates, were incorporated into the model.
Impacts on European fish stocks will vary widely depending on each species’ average temperature tolerance, the results showed.
Species such as Norway lobster, common sole, sea scallop, rock mullet and European hake are expected to decline in both numbers and distribution if sea temperatures become too warm for them.
Additionally, some larger, longer-lived species, such as swordfish, are likely to be contaminated with up to 50% more mercury than current concentration levels of the heavy metal.
Higher concentrations of mercury would make fish unsafe to eat, especially species higher up the food chain like bluefin tuna.
Greater mercury contamination would cause reproductive problems in fish that are likely to further reduce existing fish populations, the researchers also warned.
IOF Associate Researcher Dr Lam added: “The most overexploited and exploited species are being severely impacted by both climate change and high mercury levels. It is a critical situation. »
His colleague, Dr. Juan Jose Alava, who is also the principal investigator of UBC’s Ocean Pollution Research Unit, called for a “binding international agreement to reduce both carbon dioxide emissions and mercury.
He added: “This international effort should be encouraged along with the elimination of harmful fisheries subsidies to eradicate overfishing.”
Dr Rashid Sumaila, a professor at IOF and the School of Public Policy and Global Affairs, said “governments and citizens must learn to be more proactive than reactive” to avoid multiple stressors on marine life .
He added: “One way to be proactive is to listen to scientists and community members who normally sound the alarm about impending dangers.”
The peer-reviewed study “Impact of Ocean Warming, Overfishing and Mercury on European Fisheries: A Risk Assessment and Policy Solution Framework” has been published in the journal Marine Science Frontiers.
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