The overfishing threatens from the short film, but science offers a survival strategy

Shortfin Mako Sharks (Isurus oxyrinchus) are the fastest sharks of the sea, but they fail to overcome the thing even by leading them towards extinction: overfishing. Global demand for their meat and precious fins have placed this predator on the International Union for the Conservation of the Threatened List of Nature and on Annex II of the Convention on the Trade of Species Threatened with Wild flora and fauna. The situation is particularly disastrous in the Atlantic, where populations are managed as two distinct “actions”. Fishing -based assessments indicate that Northern Atlantic Makos are overvalued, but independent studies of satellite marking suggest that real fishing mortality can be ten times higher than the previous estimates. With the growing pressure of international fisheries, scientists wonder if short film makos always have genetic resilience to adapt … and if the current management strategy to treat them as two populations is scientifically solid.

A new study conduit by Dr Andrea Bernard And Professor Mahmood Shivji of Save Our Seas Foundation Shark Research Center (SOSF-SRC) And Guy Harvey Institute of the Nova Southeastern University provides crucial answers to these questions. Published in Evolutionary applicationsThe works represent the first sequencing of the complete genome of mitochondrial DNA and high -resolution nuclear DNA scans from Makos in Finfin on almost the entire range of the Atlantic. These genetic evaluations have revealed a surprising discovery (and what some say they are a finding of hope): despite decades of high fishing pressure, short film Makos always have a relatively high genetic diversity. This is very important, because genetic diversity helps species to adapt to environmental changes and survive catastrophic events. Shivji explains that although overfishing is the greatest threat to sharks in the world, many species are also faced with additional dangers of loss of habitat, exploitation on the high seas, pollution and change climate. The fact that finfin makos have maintained genetic diversity means that they can always have the capacity to adapt, but only if overfishing is interrupted before their populations are exceeded beyond the recovery point.

“As a rule, in most species of exploited sharks, we are studying, we see a fairly low diversity,” explains Shivji. “We were rather surprised, but also happy to see that the genetic health of Makos in short film does not seem to have been seriously compromised – but – by the reductions of the population caused by overhaul. (…)

This means that if we can prevent additional erosion from this genetic diversity in Mako sharks to short film by reducing the overhanging, we have more hope for this species of maintaining the necessary resilience for its populations to ‘Adapt to our climate and quick survival. »»

The research team also noted that Shortfin Makos, known for its vast ocean migrations, mix freely across the Atlantic. High -resolution nuclear DNA analyzes (hereditary of both parents) confirm that male makos will in fact largely and distribute their genes across the Atlantic. However, mitochondrial DNA – transmitted only by mothers – tells a different story. It reveals that the Shortfin female makos have a strong matrilineal structure, which means that even if they can travel a lot, they return to specific areas of their hemisphere to give birth. This confirms that the populations in the North and South of the Atlantic are genetically distinct and strengthen the need to manage them as distinct stocks.

“With an increasing loss of the genetic diversity of species and evaluations and monitoring of genetic diversity now called by the United Nations Convention on Biological Diversity as important activities to clarify national political actions for conservation and Restoration of species, data on genetic diversity that we report here for MAKO sharks provide a reference base for the evaluation and future surveillance of genetic health of this emblematic species throughout its global distribution, ”concludes the ‘team in their work. Although the genetic health of short makos offers a rare opportunity to protect their future, their resilience is not infinite. Without immediate management and stronger science and international protections, even their remaining genetic diversity will not be enough to save them. The challenge is now to ensure that conservation measures follow the rhythm of science before it is too late for one of the most emblematic predators in the ocean.