Controversy Project
For more than 400 million years, sharks have been powerful marine predators. They have survived five mass extinctions and take on a wide variety of forms and lifestyles. But due to the prevalence of overfishing and wasteful wing-cutting practices due to fisheries mismanagement, this ancient lineage is now one of the most threatened species groups in the world.
Countries around the world have introduced a series of regulations aimed at reducing shark fishing and shark finning, which often keeps valuable shark fins for use while carcasses are discarded at sea. But so far, there has been no assessment of how effective these measures are.
"Too many sharks are still dying; This is especially worrying for threatened species such as hammerhead sharks. ”
A new global assessment shows that while some regulations do work, overall, coastal fisheries are catching sharks at an increasing rate.
The findings in the journal Science are the result of an international team of researchers working to understand shark mortality trends in 150 fishing countries and on the high seas. They examined shark catches from 2012 to 2019 (during the implementation of many new regulations) to see if conservation measures had reduced species loss. They also conducted in-depth interviews with shark fishery experts to better understand current trends in shark fins and fishing activities. In summary, the dataset tracks the fate of about 1.1 billion sharks caught by fisheries around the world.
Led by researchers from Dalhousie University, the University of California, Santa Barbara, and The Nature Conservancy, the team came to a surprising conclusion. They found that the total mortality rate of sharks from fishing increased from 76 million to 80 million per year, despite a more than 10-fold increase in protective legislation to reduce finning over the same period. More than 30% of these catches are species currently threatened with extinction. If sharks that are not correctly identified by species are taken into account, the global shark mortality estimate rises to 10.1 billion.
"Unsustainable shark fishing is a global problem of staggering scale that could ultimately lead to the extinction of some of the oldest and most respected species on the planet," said senior author Darcy Bradley, an adjunct faculty member at the University of California, Santa Barbara. and a scientist from The Nature Conservancy of California. "We found that the total number of sharks killed each year by the fishery is not decreasing, despite numerous regulations aimed at curbing shark overfishing. If anything, it has changed slightly. ”
The increase was mainly driven by coastal shark fisheries. These activities account for 95% of global shark fishing mortality by the number of individual sharks caught and killed. Between 2012 and 2019, shark mortality in these fisheries steadily increased by 4%. This is in stark contrast to regulated high seas fisheries, particularly in the Atlantic and Western Pacific regions, where shark mortality is estimated to have dropped by 7%.
We show that broad legislation aimed at preventing shark fin cutting has been successful in addressing this wasteful behaviour, but has not reduced overall mortality," said lead author Boris Wurm, a research professor in the Department of Biology at Dalhousie University Nova Scotia. "Too many sharks are still dying; This is especially worrying for threatened species such as hammerhead sharks. ”
The team also analysed the relationship between individual countries' shark catches and shark fishing regulations, and found that shark fishing bans and responsible governance were the only measures associated with reducing mortality.
"A complete ban on shark fishing could be successful through conservation measures such as shark sanctuaries, highlighting the opportunity to prioritise these and other regional conservation measures," Bradley explained. ”
Nearly 70% of the world's maritime jurisdictions have introduced regulatory measures to eliminate shark fin harvesting and associated fishing mortality, which were almost non-existent 20 years ago.
Amazingly, not just one or two countries, but around the world** and some fishing companies have pledged to eliminate shark fins, often in response to public pressure. The challenge now is to build on this momentum and take stronger steps to reduce the overall shark catch," said co-author Laurenne Schiller, a postdoctoral fellow at Carleton University in Ottawa.
While the researchers found that the fin-cutting ban may reduce shark fin-cutting at sea, the provisions had little effect on the overall mortality rate. In fact, they may even increase their catches, which may be by incentivizing sharks to make the most of them and creating additional markets for shark meat and other products.
Co-author Leonardo Feitosa, a shark biologist from Brazil who currently works at the University of California, Santa Barbara, explains: "We are seeing a decrease in demand for shark fins and an increase in demand for shark meat, with Brazil and Italy being the main consumers. Since shark meat is a relatively inexpensive alternative to other fish, there is a large number of mislabels, leading some consumers to consume shark meat without knowing it. ”
The authors conclude that shark fishing continues to pose a significant threat to shark populations, but proven solutions are working. "It's clear from our analysis that cracking down on shark fins is not enough," said Echelle Burns, a data scientist at the University of California, Santa Barbara. "More concrete measures to address shark mortality – such as banning fishing in certain areas or requiring fishermen to release vulnerable species they accidentally catch – could help protect more sharks. ”
Effective shark conservation operations are often hampered by a lack of community awareness and stewardship programs," added co-author Nidi DaCosta, a shark researcher from Bangladesh who is currently working at Dalhousie. "This is especially important in countries where small-scale artisanal fisheries are a leading cause of shark mortality. ”
The authors suggest combining geographic conservation with fisheries regulations to improve the prospects for sharks. New policies need to specifically stop overfishing and the retention of threatened species, and help reduce shark bycatch. They also stressed the importance of accountability of fleets, fishing companies and governing bodies to support the successful implementation of these measures.
Our analysis highlights the need for greater transparency and reporting requirements," explains Sara Orofino, data analyst at the University of California, Santa Barbara. "Shark catches are often self-reported and aggregated into broad groups, and important information on discarding behavior is often lacking. Accurate, comprehensive, and accessible data is essential to effectively assess the role of regulations in protecting sharks and other threatened species. ”
Maria Deng Palomares, senior scientist and project manager at the University of British Columbia's Oceans Around Us program, concluded: "There is a way forward to avert the global extinction of sharks, but now is the time to act. ”
Source**: University of California, Santa Barbara.
Original Study doi: 101126/science.adf8984