Sharks can’t catch a break

A drop in reported catches is due to an increase in illegal fishing. - Momo Lin

Research at SFU has revealed that the decline in global shark and ray catches is not the result of improved conservation efforts, but instead the consequence of population declines.

In 2012, the Food and Agriculture Organization of the United Nations released a report showing an overall decrease of almost 20 per cent in reported catches since 2003.

However, the report didn’t look into why these decreases were observed; it was assumed that they were the result of improved fishing management.

Lindsay Davidson, a PhD candidate in the department of biological sciences, tested this hypothesis by studying 126 countries between 2003, the peak year in reported shark and ray catches, and 2007.

Davidson explained, “We looked at the fishing pressures and the types of management that the country had implemented, and then we tried to see what correlated with the decline in sharks and rays catch.”

Through the use of modeling, they were able to compare each country’s reported catches with their fisheries management performance and ecosystem attributes to determine which factors were playing a key role in the catch decline. Using this data they uncovered important information about not only the reason for the decline, but also what it means for chondrichthyans, the class that includes sharks and rays, around the globe.

Davidson commented that the decline “was likely driven by overfishing. We found that attributes such as indirect fishing population meat export was [. . .] associated with countries reporting a decline.”

The study also showed that there are flaws associated with the reporting of shark and ray catches because over a quarter of catches are not reported to a species level. As Davidson explained, “That doesn’t give us a lot of information about what is being caught.”

As more profitable fisheries decline, it is possible that more species of sharks will be targeted; this has been observed with the blue fin shark which has seen a 60,000 ton increase in catch rate. However, Davidson explained that while there is currently little regulation, there is still an opportunity to sustainably manage the blue fin shark and other species currently at risk.

She hopes that her research will encourage other researchers and NGOs to motivate governments to implement management tools that work.

“Sustainable fishing is possible. We have seen populations that have rebounded after some sort of strictly enforced scientifically based management measures have been put into place, so we know that this is something that is possible.”

Davidson added, “We just need to keep working towards it.”

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