A new study by an international team of scientists including researchers from The University of Western Australia, Universidade Federal de Sergipe in Brazil and the University of British Columbia has revealed an increase in the fishing of threatened sharks and rays.
The scientists found recreational catches of sharks and rays had increased over the past six decades around the world, now accounting for 5-6 per cent of the total catches.
In their paper published in Frontiers of Marine Science, the experts revealed more than 900,000 tonnes of fish are being extracted from marine waters by recreational fishers every year.
Overall, these recreational catches had grown from 280,000 tonnes per year in the 1950s to around 900,000 tonnes in mid-2010. Of this total amount, 54,000 tonnes comprises sharks and rays.
UWA Director of the Marine Futures Lab at The University of Western Australia Professor Jessica Meeuwig said in Australia recreational fishers were targeting large tiger sharks and hammerheads at beaches.
“Some species, such as hammerheads are unlikely to survive the experience of a lengthy fight and subsequently being dragged up the beach,” Professor Meeuwig said.
“Given the threatened status of these species globally, such practices put global populations further at risk.”
UWA Director of the Sea Around Us – Indian Ocean at The University of Western Australia Professor Dirk Zeller said even though information was scarce and difficult to compare, the researchers had been able to learn about what is being caught and had been caught in 125 countries over more than 60 years.
“We have assembled the first comprehensive global estimate of marine recreational catches, which is a major accomplishment,” he said.
“Even approximate estimates are better than saying ‘we have no data’ which translates into there are ‘zero recreational catches,’ which is not true in most countries and leads to an under-valuation of recreational fisheries and their impact on fish populations.”
Universidade Federal de Sergipe Professor Kátia Freire said the shark and ray catches started in the 1990s and were particularly significant in Oceania and South America.
“We may be underestimating the real amounts, as accessing recreational fisheries data is particularly difficult,” she said. “Most countries do not compile this data, or those that do, do not incorporate them it their national fisheries statistics that are reported to the Food and Agriculture Organization of the United Nations.”
Professor Daniel Pauly, from the Sea Around Us initiative at the University of British Columbia, said the problem with sharks and rays was that even if they were thrown back into the ocean, a practice that is not uncommon as many recreational fishers now practice ‘catch-and-release,’ not all individuals survive.
“For example, 98 per cent of scalloped hammerheads die,” he said. “The biology of sharks makes them slow when it comes to growing and maturing, which means that they produce only a small number of young in their lifetimes. If many individuals are caught before they have been able to reproduce sufficiently, then their population numbers start to dwindle.”