As attacks increase, do shark culls work? Here’s what the science says
As attacks increase do shark culls – A recent incident at Coogee Beach in Sydney has reignited discussions about the effectiveness of shark culling programs. A young mother, Leah Stewart, 35, was attacked by a shark on Saturday morning while swimming approximately 30 meters from shore. The predator, believed to be a great white shark measuring between three to four meters, struck her in what has been described as a tragic and alarming event. This incident has prompted calls for action, with some arguing that culling sharks could be a necessary measure to protect beachgoers.
Political Responses to Rising Threats
Following the attack, prominent political figures have weighed in on the issue. Federal Liberal Party president Tony Abbott emphasized the need for more aggressive measures, stating:
“It’s so wrong that we don’t cull sharks after attacks. It’s so wrong that we don’t have a commercial shark fishery given the explosion of shark numbers, and it’s so wrong that we don’t put people before sharks.”
Abbott’s remarks highlight the growing concern over the balance between marine conservation and public safety. In response to the surge in bull shark bites during the summer months, New South Wales Premier Chris Minns has indicated his government is exploring the possibility of culling bull sharks in certain areas.
Global and Local Patterns in Shark Bites
While the Coogee incident has drawn attention, it is part of a broader trend. Over the past four decades, shark bites have increased both in Australia and globally, though the overall frequency of such attacks remains relatively low. This uptick raises questions about the underlying causes. Are sharks becoming more numerous, or is human activity influencing their behavior? The debate hinges on interpreting the data accurately.
Australia’s shark populations, particularly species like the great white and bull shark, are subject to various conservation efforts. The country has implemented protections and managed fisheries that have contributed to the recovery of vulnerable species. However, despite these measures, the number of shark bites has still risen. This suggests that factors beyond population growth may be at play.
Scientific Insights on Risk Factors
Charlie Huveneers, an Associate Professor at Flinders University, recently co-authored a study examining the causes of increased shark bites. The research identified 40 potential factors that could influence bite risk, including human population growth, habitat degradation, declining water quality, climate change, and shifts in the distribution of sharks and their prey. These factors, while interconnected, are not mutually exclusive, making it challenging to isolate a single cause for the observed trend.
One of the study’s key findings is that the infrequency of shark attacks limits the ability to pinpoint the most significant contributors to the rise in incidents. For instance, while the recovery of great white sharks and reduced fishing pressure might be expected to lower their numbers, these factors alone cannot fully explain the increase. Instead, the data suggests a combination of environmental and behavioral changes is likely driving the trend.
Effectiveness of Shark Culling: A Mixed Picture
Shark culling has long been a contentious strategy. Some research indicates that targeted culling can reduce human-shark interactions in specific locations. For example, in certain areas where culling programs were implemented, bite rates declined. However, other studies have found no consistent impact after large-scale culling initiatives. This discrepancy underscores the complexity of the issue.
The effectiveness of culling varies depending on the species and region. Great whites, bull sharks, and other large predators may respond differently to removal efforts. Moreover, the exact number of sharks required to be eliminated to see a meaningful reduction in bites is unclear. In some cases, culling could take a significant toll on shark populations before it begins to influence bite rates.
Alternatives to Culling: A Broader Approach
While culling remains a popular option, experts argue that alternative measures are often more effective and less harmful to marine ecosystems. Techniques such as drone monitoring, SMART drumlines, and shark listening stations have gained traction as viable solutions. Drones, for instance, can detect sharks in real time, allowing for rapid evacuations of swimming areas. SMART drumlines, which use baited lines to capture sharks near shore, enable authorities to tag and relocate the animals, reducing the need for lethal removal.
Shark listening stations, equipped with acoustic tags, provide early warnings by tracking the movement of dangerous species. These non-lethal methods are designed to minimize ecological disruption while still safeguarding ocean users. However, their success depends on consistent implementation and public adherence to safety protocols.
Long-Term Impacts of Culling Programs
The example of Hawaii’s shark control program in the 1960s and 1970s illustrates the potential limitations of culling. Over the course of those years, 4,668 tiger sharks were killed as part of the initiative, yet there was no measurable decrease in the rate of shark bites. This outcome suggests that culling may not always address the root causes of human-shark encounters.
Shark nets, a common tool in culling efforts, also have unintended consequences. While they aim to intercept dangerous species near popular swimming zones, they often result in the deaths of non-threatening sharks, rays, turtles, and dolphins. Critics point out that these nets may not effectively reduce the risk to swimmers, as they can also trap sharks that are not actively posing a threat.
Striking a Balance Between Safety and Conservation
The challenge lies in balancing the need for safety with the preservation of marine biodiversity. While shark culling offers a direct approach to reducing encounters, it may not be the most sustainable or effective solution in the long term. The study by Huveneers and his colleagues underscores the importance of considering multiple factors, including climate change and human activity, when evaluating the causes of increased attacks.
Public awareness and education also play a critical role. By understanding the behaviors of sharks and the factors that contribute to their interactions with humans, communities can adopt more nuanced strategies. These might include seasonal warnings, avoiding swimming during peak activity times, and using protective gear like wetsuits and shark deterrents.
Ultimately, the question of whether shark culls work is not black and white. While they may provide temporary relief, their long-term impact depends on careful planning and a holistic approach to marine conservation. As the debate continues, the focus remains on finding solutions that protect both people and the ocean’s diverse ecosystem.
This article was first published by The Conversation and is republished under a Creative Commons licence. Read the original article for further details.
