Great white sharks have divided into three distinct groups that rarely interact.

One idea for JAWS 2 was to have two Great White sharks terrorise the residents of Amity Island. However, a recent study has found that Great Whites prefer a different approach. A groundbreaking genome analysis by an international team of scientists has revealed that global great white shark populations split into three distinct groups nearly 200,000 years ago and have largely stayed within these groups ever since.

These three populations are: the southern Pacific Ocean group (also known as the Indo-Pacific crowd), a northern Pacific Ocean group, and a group that prowls the North Atlantic and Mediterranean.

Dr. Catherine Jones from the University of Aberdeen led this research effort, collaborating with experts from the Guy Harvey Research Institute, the MedSharks project, and the Oceans Research Institute. Their findings indicate that these three shark populations have remained genetically isolated, with little interbreeding among them.

"During the Penultimate Ice Age, between 100,000 and 200,000 years ago, great white shark populations diverged into three distinct lineages that rarely interbreed," Dr. Jones explains. "Today, these lineages remain separate, with modern ocean currents acting as natural barriers that keep each group in its respective region."

This division among great white sharks is more than just a fascinating tale of marine biology—it has significant implications for conservation. Because each population is smaller and isolated, the risk of extinction is greater than previously understood. If one group suffers a decline, the others are unlikely to compensate, threatening the genetic diversity and stability of the species.

The stakes are high, particularly if unique lineages like those in the Mediterranean disappear. This loss would mean more than just fewer sharks in the sea—it would represent the permanent loss of a unique genetic lineage.

Professor Les Noble of Nord University underscores the urgency, stating, "White sharks are crucial to the health of marine ecosystems. Over the past 50 years, their numbers have nearly halved, and they are now critically endangered in Europe."

The potential impact of shifting ocean currents over the next 50 years adds another layer of complexity. If these currents change, the geographic barriers between shark populations may weaken, leading to more interbreeding. However, as Professor Galice Hoarau of Nord University notes, "The lack of interbreeding suggests that cross-lineage offspring may not be viable, which could further endanger white shark populations and disrupt ocean ecosystems."

To address these challenges, scientists are calling for innovative conservation strategies. A deeper understanding of the distribution and health of these distinct shark populations is essential to protect them from extinction. Immediate action is needed to counter threats like bycatch fishing, habitat loss, pollution, and poaching.

Dr. Jones warns, "It was once thought that sharks lost in one region could be replaced by others moving in from elsewhere. Our findings show this is unlikely."

With their vital role in maintaining marine ecosystems and their critically endangered status, it's clear that preserving these apex predators is crucial. The research, published in Current Biology, emphasizes the need for urgent conservation efforts to ensure that great white sharks continue to thrive in our oceans for generations to come.

The study is published in the journal Current Biology.

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