Project Results

For the results I presented at the Brazilian conference, we analyzed 25 samples and found 15 haplotypes. These data were compared to contemporary data from Australian (Feutry et al., 2015) and the haplotypes in Brazil did not match any of the haplotypes seen in Australia. The average haplotype diversity was 0.930 which is high compared to other elasmobranchs and the average nucleotide diversity was 0.002 which is low but typical for elasmobranchs. 

About This Project

The Critically Endangered Largetooth Sawfish is one of the most threatened of all marine fishes. They have historically been, and still are, exploited for their toothy saw. After global declines, Brazil is likely the last place this species is found in the Atlantic.This project aims to use DNA from old saws to assess Largetooth Sawfish genetic health in Brazil which is a critical step to giving this species a fighting chance against extinction.

Ask the Scientists

What is the context of this research?

Largetooth Sawfish in Brazil are vital to the survival of this species because outside of the Indo-West Pacific, Brazil is thought to have the largest, and likely the only, remaining population in the Atlantic of this once circumtropical ray. To effectively develop management plans for this species in Brazil we first need to understand their genetic health. Our knowledge of the genetic health of Largetooth Sawfish in Brazil is limited because they are so difficult to find and sample from in the wild. We are currently using the DNA from old saws found in museums to assess the genetic health of Largetooth Sawfish globally but had few samples from Brazil until one of our team members was able to gather over 100 old saws in Brazil for us to use.

What is the significance of this project?

The IUCN Shark Specialist Group recognizes Brazil as a “Beacon of Hope” population for Largetooth Sawfish and the first step to effectively managing this population is to understand their genetic health. The Largetooth Sawfish specimens our team member has in Brazil provide our only opportunity to gather their genetic data because this species is too rare to collect DNA from wild individuals. Analyzing the DNA from these specimens will immediately tell us how much genetic diversity is found in Largetooth Sawfish in Brazil and how genetically unique Brazil is compared to populations left in the Indo-West Pacific. Our earlier research has suggested that Brazil may be the last population of a genetically distinct Atlantic/Eastern Pacific clade of Largetooth Sawfish.

What are the goals of the project?

This project aims to analyze the genetic health of Largetooth Sawfish in Brazil by looking at their genetic diversity. The higher the genetic diversity the more equipped a population is to adapt to changes in their environment and withstand disease. We will use Largetooth Sawfish saws that were historically taken from sawfish in Brazil and kept as trophies. Our team member and colleagues were able to find over 100 saws in museum collections, people’s homes, etc. We will extract DNA from these saws using techniques we developed for saws and then amplify the DNA.We need funding for the final step in this process which is to determine the DNA sequence to analyze how much genetic diversity is found in the Brazil population.