The largest shark species, such as tiger sharks and great whites, have a strong ecological role in healthy oceans, but they have been the most severely affected by fisheries. Seven decades of industrial over-fishing has so depleted them that in vast regions they no longer fulfil their ecological functions.
Tiger shark off the Bahamas. Sharks occupy a wide variety of niches and are essential to ecosystem functioning.
A new study has shed light on the surprising ways that the great sharks contribute to their ecosystems. They help transport nutrients across marine ecosystems, which involve a variety of marine life forms. As the climate warms and human activities continue to alter ocean conditions, their roles are shifting. Some species are expanding their ranges into cooler waters, affecting new areas and interactions. Changes in their distribution can disrupt local ecosystems because, as apex predators, they play a crucial role in maintaining the balance of marine ecosystems and can take different roles in different environments.
By controlling the populations of other species, large sharks indirectly help maintain habitat quality and boost carbon sequestration, making such ecosystems more resilient to climate change. Their hunting practices can influence the entire food web. The tiger shark, for example, has been shown to have a significant impact on coastal seagrass and kelp forests.
Researchers are exploring how restoring the populations of great sharks could help restore ecological balance in diverse marine environments and even enhance the ocean's ability to absorb carbon dioxide.
Complex interactions
However, understanding the full extent of their ecological roles remains a challenge. The complexities of their interactions with various species and habitats often make it difficult to grasp their true impact. While some shark species have been well studied, others—particularly those in deep waters—remain poorly understood.
To protect and restore these vital predators, conservation efforts must focus not just on increasing shark populations, but also on preserving their ecological functions. The main challenge is eliminating their take by industrial fisheries, which continues to devastate them. Balancing commercial interests with ecological health will be key to ensuring they continue to thrive and support healthy, resilient marine ecosystems.
As scientists and policymakers work to address these challenges, the message is clear: safeguarding shark populations is not just about protecting a species, but also the health of our planet's oceans and climate.
