Shortfin mako sharks are among the fastest fish in the ocean. Yet, these majestic predators are in serious trouble due to overfishing. They are increasingly sought after for their meat and valuable fins, putting them on the endangered list of the International Union for Conservation of Nature. The situation is particularly critical in the Atlantic, where two separate populations, or “stocks,” are recognized. While assessments show that northern Atlantic makos are overfished, some independent studies suggest that the real rates of fishing could be much worse—up to ten times higher than previously thought.
Scientists are worried about whether shortfin makos still have the genetic diversity needed to adapt to changes in their environment. A recent study led by Dr. Andrea Bernard and Professor Mahmood Shivji reveals important insights. This study is the first to completely analyze the mitochondrial DNA and nuclear DNA of makos across almost the entire Atlantic. Surprisingly, researchers found that shortfin makos still maintain a good level of genetic diversity, even after years of heavy fishing. This is crucial because genetic diversity plays a key role in helping species adapt to changing environments and survive crises.
Dr. Shivji noted that while overfishing is a significant threat to shark populations, they also face other dangers like habitat loss and climate change. The fact that shortfin makos retain their genetic diversity means there’s still hope for them, but only if fishing practices are improved before these sharks reach a point where recovery is impossible.
Typically, when scientists study sharks, they find low diversity, which raises concerns for their survival. In this case, however, the genetic health of shortfin makos appears stable, which is encouraging. Stopping further declines in their genetic diversity is essential for ensuring that these sharks can adapt to a rapidly changing world.
This study also provided insights into the movement of shortfin makos. They are known for their extensive migrations across the ocean. Males tend to travel widely, mixing their genes throughout the Atlantic. However, females show more defined breeding behaviors, returning to specific areas to give birth. This indicates that northern and southern Atlantic makos are genetically distinct, affirming the need for separate management strategies for these populations.
The findings of this research set a baseline for monitoring the genetic health of shortfin mako sharks and could inform future conservation efforts. However, their genetic resilience has limits. Without better fisheries management and stronger protections, even their relatively high genetic diversity might not be enough to save them. The challenge lies in ensuring that conservation efforts keep pace with scientific discoveries, so we don’t lose one of the ocean’s most remarkable predators.
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