Climate Change: A Growing Tide Of Shark Attacks

Shark attacks are on the rise, with 98 reported bites in 2023, an 11% increase from the previous record in 2000. Experts attribute this increase to climate change, with warming ocean temperatures pushing sharks northward, towards more densely populated areas. Warmer weather also means more people are swimming, increasing the likelihood of shark-human encounters. While the number of shark attacks has risen, an individual's chance of being attacked by a shark has not, as the human population is increasing faster than the shark population.

Warmer ocean temperatures push sharks northward, increasing shark-human encounters

Warmer ocean temperatures have a significant impact on marine ecosystems, and this includes driving sharks to migrate northward. According to a study by Progress in Oceanography, climate change is causing shark species to move from the sparsely populated southern hemisphere to the more populated north. This shift increases the likelihood of shark-human encounters.

The oceanic whitetip shark, for instance, is already facing pressure from commercial fishing. Warmer oceans could further threaten their populations by altering the distribution and quantity of their prey and limiting their preferred habitat. As the ocean warms, prey species will need to migrate to follow their nutrient cycles, and the sharks will need to follow their prey to survive.

Sharks are cold-blooded animals, and as the surface waters warm, they will dive deeper to regulate their body temperature. This behaviour will impact the movement patterns of sharks and may affect their ability to maintain sufficient body temperatures.

In addition to the direct impact on shark behaviour, warmer ocean temperatures also mean more people are likely to go swimming, creating a potentially fatal combination. Warmer temperatures also mean more beachgoers and bathers, providing more potential prey for sharks.

The combination of these factors—the northward migration of sharks, the increase in human activity in warmer waters, and the potential for changes in shark behaviour—contributes to the rise in shark-human encounters and, consequently, shark attacks.

Warmer weather means more people go swimming, increasing the chances of shark attacks

Warmer weather is one of the factors that increases the chances of shark attacks. As the ocean temperatures rise, more people are drawn to beaches and waters for swimming, snorkelling, scuba diving, and surfing. This increase in human activity in the ocean puts people in closer proximity to sharks, creating more opportunities for shark attacks.

The combination of warmer weather and human activities in the ocean is a potentially fatal combination. Warmer temperatures not only bring more people to the water but also create favourable conditions for shark populations to thrive. As a result, the chances of encounters between humans and sharks increase, leading to a higher risk of shark attacks.

According to George Burgess, director of the Florida Program for Shark Research, "Each year we should have more attacks than the last because there's more humans entering the water, and more hours spent in the water." The rise in ocean temperatures due to climate change is a significant factor in this increase.

While the number of shark attacks has been rising, it is important to note that the individual's chance of being attacked by a shark has not increased proportionally. This is because the human population is increasing at a faster rate than the shark population. However, as more people are attracted to the water by warmer temperatures, the absolute number of shark attacks is likely to continue rising.

To reduce the risk of shark attacks, it is essential to address the underlying causes, such as climate change and human activities that impact shark habitats. By understanding and mitigating these factors, we can help ensure that the enjoyment of warm weather activities in the ocean does not come at the cost of increased shark-human encounters.

Climate change impacts prey availability and habitat quality for sharks

Climate change is impacting prey availability and habitat quality for sharks. As the oceans warm, prey species are migrating to follow their nutrient cycles. If prey becomes scarce, some shark species will need to move with their prey to survive. For example, oceanic whitetip sharks prey on large pelagic fish and squid, which are also affected by climate-induced ecosystem changes. As the ocean temperature rises, the distribution and quantity of their prey will change, and the availability of their preferred habitat may be limited.

Sharks are also shifting their geographic distributions based on prey and habitat availability. In Atlantic and Pacific U.S. waters, many fish species are moving northward as the oceans warm. For instance, thresher sharks, common off southern California, are expected to become more common off the coast of Alaska. Some species are also moving to deeper, cooler waters as shallow coastal environments warm.

The complex and variable life histories of sharks mean that climate change will impact individual species differently. For example, scalloped hammerhead sharks rely on shallow, coastal areas such as bays and mangroves for breeding habitat. Their pups and juveniles are particularly vulnerable to intense storms and flooding, which can increase freshwater runoff and sedimentation, impacting water temperature and nutrient cycles.

Giant manta rays, which feed on zooplankton, are also affected by climate change. As ocean temperatures increase, the spread of nutrients that support zooplankton populations will be impacted. Changes in zooplankton availability could affect the behaviour and health of giant manta ray populations, potentially leading to shifts in seasonal migration patterns and profound impacts on their survival.

Climate change is causing warming seas, ocean acidification, rising sea levels, and other long-term environmental shifts. These conditions can have critical effects on the health and distribution of marine species, including sharks. As these climatic events intensify, the recovery of endangered species will become more challenging.

Coastal development and infrastructure can displace sharks, forcing them closer to humans

Coastal development and infrastructure projects can have a significant impact on shark behaviour and distribution, leading to an increase in shark bites. Dr Blake Chapman and Dr Daryl McPhee, researchers at Bond University in Queensland, Australia, assert that "coastal development and infrastructure can have major environmental implications on the distribution of sharks, and this can flow on to the number of unprovoked shark bites".

One notable example is the construction of the Suape Port in Recife, Brazil, which resulted in a sharp increase in shark attacks. The destruction of their natural habitat forced sharks to migrate closer to human-populated areas. The researchers noted that "unprovoked shark bites were virtually unheard of in Recife" before the development of the port. The environmental changes and increased shipping activity displaced local shark species, leading to a significant rise in shark-human encounters.

Similarly, changes in regulations and tourism trends can also influence shark populations and the likelihood of attacks. For instance, the Bahamas witnessed a rise in shark numbers after banning commercial shark fishing in 2011 to protect the shark dive industry. While this decision did not immediately impact the number of shark bites, the growing shark population suggests that future attacks may become more frequent.

In addition to coastal development, warming ocean temperatures caused by climate change also play a crucial role in shark migration patterns. As ocean temperatures rise, shark species are pushed from the warmer, sparsely populated southern hemisphere towards the cooler, more densely populated northern regions. This shift increases the odds of shark-human encounters, especially as higher temperatures also attract more beach-goers and swimmers.

The combination of coastal development, infrastructure projects, and the effects of climate change can displace sharks and force them closer to human-populated areas. These factors contribute to the rising number of shark attacks, highlighting the complex interplay between human activities and the natural behaviour of these predators.

Warmer seas allow shark populations to increase rapidly

Warmer sea temperatures caused by climate change have a significant impact on marine ecosystems. As a result, shark species are moving from the sparsely populated southern hemisphere to the more populated north, increasing the odds of shark-human encounters.

The increase in sea temperature also affects the distribution and quantity of prey for sharks. As prey species migrate to cooler waters to follow their nutrient cycles, sharks will need to move with them to survive. This can lead to sharks moving into closer contact with humans.

The warmer waters also mean that more people are likely to go swimming, increasing the chances of shark attacks. This is especially true in tourist hotspots, where the number of people entering the water is higher.

In addition, the warming oceans can affect the movement patterns of sharks and their ability to maintain sufficient body temperatures. These behavioural changes in top predators can have cascading effects on the populations of other species and the health of the ocean.

The combination of these factors means that while the rate of shark attacks per million people has stayed relatively flat, the overall increase in the global population means that the number of shark attacks is likely to continue to rise.

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