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Judi Lynn

(160,217 posts)
Mon May 25, 2020, 10:19 PM May 2020

What Happens Next In Brazil Is Crucial For One Shark Species

May 25, 2020,09:25pm EDT

Melissa Cristina Márquez Contributor

Sharks are among the most endangered and data poor vertebrates in the world. Shark populations worldwide are subjected to a myriad of threats, such as overfishing and habitat degradation, which is concerning scientists about their long-term sustainability.

Sharks in Brazil are no different. Knowledge about how sharks use their habitats is limited, and this is problematic in and of itself for their overall conservation and management. If scientists lack shark habitat use knowledge, how can they protect them as priority areas for overall species conservation? One tool that is being used to better understand how sharks use their environments is by investigating the trace elements present in their vertebrae. This allows researchers to analyze species habitat use over individuals’ lifetimes. A team of scientists decided to apply vertebrae microchemistry to investigate habitat use of one particular shark, the smalltail shark (Carcharhinus porosus) in Brazil’s Northern Coast (BNC). “We did this project because our lab has been working with vertebrae microchemistry for a while, but never with a species from the Amazon coast. The region is a great mystery to us all, especially because we know very little about the abiotic features of the habitat. Its also one of the largest fishing areas in Brazil, and Dr. Lessa felt that applying this technique to investigate habitat use was a great opportunity,” said scientist Leonardo Manir Feitosa of Universidade Federal de Pernambuco in Brazil.



The smalltail shark (Carcharhinus porosus). KEYTON KYLSON FONSECA COELHO FROM UNIVERSIDADE FEDERAL DO MARANHÃO

This gray small (almost 5 feet long or <1.5 meters) shark occurs in the Western Atlantic. With its long, pointed snout and large eyes, it thrives in the muddy bottoms of estuaries where they hunt small fish and invertebrates. Due to being a smaller shark, they are often preyed on by larger sharks; they are also primarily caught as incidental bycatch in the gillnets of other fisheries. Increasing directed fishing effort by artisanal fisheries is the primary reason for this species' decline.

“We chose to focus on the smalltail shark because it is a critically endangered species in Brazil from which not a lot of information is available. It was the most important shark in terms of catch composition in northern Brazil during the 1980s and, from then on, its catches plummeted around 85%. Catches never increased since, so we needed to know how it uses the habitat in the Amazon coast to determine more effective conservation actions,” explained the Feitosa and Dr. Lessa in a joint statement.

More:
https://www.forbes.com/sites/melissacristinamarquez/2020/05/25/what-happens-next-in-brazil-is-crucial-for-one-shark-species/#4450609d5d0e

Also posted in Environment and other articles:
https://www.democraticunderground.com/1127138089

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