SOURCE: The Revelator
DATE: October 14, 2020
SNIP: Oh what a difference a few decades make.
Back in in the 1980s and 1990s, a species known as the smalltail shark (Carcharhinus porosus) was one of the most common fish caught off the coast of northern Brazil.
That’s not the case anymore. A new paper by researchers from a trio of Brazilian science institutions calculates that smalltail shark populations in the country have declined by a shocking 90%. They say the species has now become critically endangered and is in need of “urgent conservation methods…to prevent its extinction in the near future.”
The problem, as with so many other declining oceanic species, stems from rampant overfishing.
In this case smalltail sharks face similar threats from two very different types of fisheries. Small-scale, artisanal fishers use gillnets to catch species like mackerel and weakfish, while industrial-fishing operations use trawl nets to catch shrimp and massive gillnets to scoop up catfish and other bottom-dwelling species. These industrial gillnets regularly reach up to 5.5 miles in length.
Each of these methods indiscriminately catches a wide range of species, including smalltail sharks, which swim in muddy coastal waters and estuaries. The sharks only reach 3-4 feet in length, so they’re easily swept up by these fishing operations.
Amplifying the fishing threat, the paper reports, a majority of smalltail sharks caught by the fisheries have always been juveniles. In the 1980s sharks younger than six years accounted for 90.6% of catches.
The elimination of so many immature sharks from the population removed any chance they’d get to breeding age and perpetuate the species.