When the number of shark incidents surged in Western Australia, people panicked and blamed a growth in the white shark population. Charlie is using genetics to determine how many white sharks there really are to inform decision-making.
Although I am originally from Belgium, which has only a 60-kilometre coastline, I have always been attracted to the ocean. My homeland’s marine fauna and flora may not be renowned for bright colours or amazing diversity, but they were enough to spark an interest in the underwater world that has become a lifelong fascination.
My specific interest in sharks started when I was 11 years old. Our teacher asked us to do a presentation on an animal, and while most of the children did theirs on cats or dogs, my mother suggested that I do mine...
This project will examine evidence for changes in the effective size of the Australian great white shark population based on genetic comparisons of historical and contemporary samples.
Emotions following recent shark incidents and growing public concern about the risk that sharks pose to swimmers in Australian waters led the Western Australian government to announce in 2012 that it will allocate $2-million to allow the state’s Department of Fisheries to track, catch and destroy white sharks that pose a threat to humans. For this reason, our project occurs at a time of critical need for the species. We will provide – for the first time – real data so that the state and Australian governments can respond to public and media pressure in a reasoned and rational manner, rather than having a political agenda determined by emotive and anecdotal arguments.
Although fatal shark attacks are relatively rare (on average 1.2 per year), a recent dramatic upsurge in attacks in Western Australia during the course of less than 12 months (five of which were fatal) has led to concerns that this might be linked to a sudden increase in the white shark population. The core of this debate – whether white sharks could have increased in abundance to a level impacting human safety since their protection 15 years ago – has never been addressed by a rigorous scientific study. This fundamental uncertainty has meant that arguments about the status of white shark populations and the threat that they pose are largely based on conjecture, anecdotes and emotion. It is these non-scientific views that now drive the political agenda that has the potential to alter the population status and future of these sharks for many years to come. Our project directly addresses this issue.
We will examine evidence for changes in the effective size of the Australian white shark population based on genetic comparisons of historical and contemporary samples. Fishermen have collected the jaws of great white sharks as trophies for many years. We will use these jaws (we have identified about 100 in both private and public holdings) to estimate effective population size prior to protection. This estimate will then be compared to the effective population size deduced from contemporary samples collected as part of our tagging studies. Although building on earlier work by co-investigators, the analysis will use new, state-of-the-art methods and advanced biostatistics to identify changes in population size. Our aim is to provide data on trends in the population sizes of great white sharks that can be used to inject hard data into the debate about the future of white sharks in Australian waters.
We will examine evidence for changes in the effective size of the Australian white shark population based on genetic comparisons of historical and contemporary samples. Specifically, we will:
As gray seal populations have recovered, the coastal waters off Cape Cod have become the only known aggregation site for white sharks in the western North Atlantic. Greg is estimating seasonal predation rates of white sharks on seals and identifying which environmental conditions are associated with predatory behaviour in order to improve public safety practices.