Lies, Damn Lies and Killing Sharks (Part 2)

My last post about the Commonwealth of Australia’s approval of shark cull program in the State of Western Australia focused on the use of statistics with low power, and low merit, to amplify the argument that shark attack incidents in recent years are a cause for concern. Similarly the lack of statistics and use of anecdotal evidence to hype the economic downturn alleged to be caused by the flurry of shark attacks was red-flagged as being a poor substitute for proper analysis, particularly where the proposed solution was the targeted killing of animals listed as vulnerable to extinction or near threatened.

This post will look at the remaining points I listed as being the reasons provided by Minister Hunt for granting an exception to the Environment Protection and Biodiversity Conservation Act 1999 (Cth) for the cull, being:

1. A statistically significant increase in shark attack strikes in Western Australia in the years 2010 to 2013 compared to population increase;

2. As a result of point 1, people are scared of entering the water and there is anecdotal evidence of tourist businesses suffering financially;

3. The proposed cull will reduce the incidence of shark attacks and will provide useful information to other states in dealing with the same problem;

4. The West Australian government has implemented measures to reduce the risk of death to other sea life from the exercise; and

5. It is in the national interest (due to points 1 to 3 above) for the cull to be allowed, and therefore within the class of reasons the EPBC Act gives as being the basis for an exemption to be allowed.

3. The proposed cull will reduce the incident of shark attacks and will provide useful information to other states in dealing the same problem

The most striking aspect of this section of the approval is that, when read without any insight into shark control measures already in place in our own country let alone any other country, it would seem that this was a pioneering approach that would be provide new insights in this problem.

New South Wales and Queensland have implemented and maintained shark control measures since 1937 and 1964 respectively. Queensland and KwaZulu-Natal in South Africa, which also has shark control program presently operating, utilise netting and drum-lines just like the West Australian culling program proposed to use. Programs have also been implemented in New Zealand, Brazil and Hawaii.

Although literature on the results of shark cull activities was limited from my searches, Minister Hunt could have easily obtained a detailed report on the effects, both good and bad, of such a cull. Indeed, the State of Western Australia had already engaged Associate Professor Daryl McPhee of Bond University to provide a report to the West Australian Department of Fisheries in which he explains the objectives of his report as including a literature review of studies and reports on shark exclusion programs in other jurisdictions.

The report is not long (23 pages) and easy to read. It follows from the report that perhaps the only change to result from the program will be analogous to the placebo effect; make people feel like they are safer while the treatment offered has no effectual value.

There are noted problems with using shark attack data from New South Wales and Queensland to assess the effectiveness of those programs however. Associate Professor McPhee’s report doesn’t specify how effective those programs have been and nor could he. Any assessment can’t be controlled for other variables, such as increasing efficiency and expertise in providing aid to injured victims from becoming fatal victims, that will affect the analysis. This point he makes clear. He makes further comments about the variability of the programs in those states and internationally which wreak havoc on assessing the impact of these programs.

Similar to the basis of my critique of the statistical significance of the increase in shark attacks in my last post, a statistical analysis of these existing programs will be beset by problems of low statistical power.  This was amply illustrated by Jessica Meeuwig of the Centre for Marine Futures at University of Western Australia, who was driven to write on the subject given the same pretence as I am now writing. After analysing the data on shark fatalities in Queensland she concluded:

“This highlights the problems we face when trying to understand patterns in shark attacks and the effect of mitigation programs – fatalities are such rare events that differentiating between random coincidence and underlying patterns is fraught with difficulty”.

With that limitation on her analysis put forth, she found that that data indicated declines in shark-related fatalities in areas both with and without drum lines, and that the greatest decline in fatalities was prior to the installation of drum lines.

We already have similar programs in place to look to if this solution is the fancied solution and the data obtained is likely to be no different than that obtained in West Australia; the effectiveness cannot be measured to exclude random chance or independent, uncontrolled variables from being the cause of increases or decreases in shark attack numbers.

4. The West Australian government has implemented measures to reduce the risk of death to other sea life from the exercise

If the preceeding three sections outlined the problems with evaluating the effectiveness of a cull on protecting human life, the problem with this point 4 of the basis for allowing the program is almost opposite. The problem of by-catch of shark programs is of critical concern to those who have researched the effect of netting and drum-line programs.

Associate Professor McPhee evaluates this risk as long established. Citing data from the New South Wales, Queensland and South African programs he lists non-targeted species of shark and other animals such as rays, turtles, dugongs, seals, dolphins and whales as being the worst affected. He further notes the high incidence of by-catch in the initial years of these programs, an important fact should the approval for this program not be renewed in following years but re-implemented again at a later time. These implications, coupled with the dubious evidence of effectiveness of meeting the stated aims of the proposal, led him to recommend the West Australian Department of Fisheries against initiating such a program.

Paterson’s 1990 report “Effects of Long-Term Anti-shark Measures on Target and Non-target Species in Queensland, Australia” found that these measures have continuing deleterious effects on non-target species including the ones listed above. Problematic for such mitigation strategies is that some species affected are also listed species needing protection. While Paterson indicated the program to be a success in decreasing human injuries, a conclusion to be sceptical of in light of the above, his conclusion about the effect on non-target species adds historical weight to the problem of this significant side-effect.

Further, and possibly more importantly for the effectiveness of the program compared to detrimental impacts, he found that anti-shark measures in Queensland were most successful against indigenous sharks, not migratory sharks. The Great White Shark, one of the target species of the West Australian cull and the species most commonly involved in shark attack incidents, is a migratory shark with the West Australian coastline thought to be on the shark’s migration route. Meeuwig’s article above noted that in Queensland less than one percent of the sharks caught were Great Whites, while 97% of the sharks caught were conservation listed.

Development of non-lethal methods and technology as well as the use of current methods with greater effectiveness are noted in the above reports. An example is given of surface to seafloor netting at designated beaches in Hong Kong that completely separate sharks from swimmers, unlike the nets currently used in Australia, with added design factors to limit the fatal effects of netting on sea life. The Department of Fisheries in West Australia has itself been researching the use of repulsion devices that are effective for deterring sharks but have little or no effect on non-targeted species. It also has in place a monitoring program to track shark movements around the coastline.

A study by Caldicott et al looked for consistent factors surrounding shark attacks to find correlations between environmental factors and increased incidents of shark attack; colour, sound frequencies and electrical fields were found to attract shark activity. This information can assist in the development of non-lethal shark-repulsing methods and better education of the ocean-going public to reduce the likelihood of interaction between sharks and people.

The West Australian government, with the help of the Commonwealth Government, has determined that the risk posed by the use of netting and drum-lines is a reasonable risk to take. This is despite what appears to be overwhelming data showing the significant risk posed to numerous threatened species given the indiscriminate death the results from use of this equipment.

5. It is in the national interest for the cull to be allowed given all of the above

‘National interest’ appears to be a term that, despite any attempt to pin it down to a precise definition, can float back to the surface to be used again with an alternate or expanded definition to justify its use. Its use in this scenario must be considered a case study on point.

National interest is given a non-limiting definition in subsection 5 of the EPBC Act as being cases of defence, security or national emergency. I don’t believe the sharks are mounting an offence against Commonwealth and surely, given the oft quoted comparisons of road fatalities, drug and alcohol related fatalities, bee sting fatalities, etc, to shark attack fatalities, the supposed concerning increase in the latter within one State must mean that almost any state of affairs, even if limited to small geographical area and a few adverse outcomes, could see the national interest being used to justify intervention.

It therefore must be defined in this case outside those three considerations provided for in the Act. Given the claims of economic harm the term must be defined as relating to the economic interest of the country. I could envisage a widespread plague of unrestrained creatures, freed from ecological balance by the drastic reduction in predators, resulting in people being forced to stay on dry land and thereby effecting national tourism, as being a problem deserving of attention under the National Interest. I could see destruction of pristine areas of our natural land and sea environment as being in the national interest due to effects on the fishing industry and tourism, not to mention the loss of national natural assets recognised internationally, as being considered in the National Interest. It seems a long bow to draw to mount a case that one business’ reported reduction in scuba diving pupils is the platform to argue that this action is required in the National Interest

Either the benchmark for what meets the definition of national interest has been dropped to justify any issue of limited geographical, economic or health concern falling within its purview or the issue of shark attacks in West Australia has been bloated to seem like it should fit – I would argue it is the latter.


1. Stating that the increase in shark attacks is statistically significant, while correct, fails to address the limitation of statistical analysis of the shark attack data given the low numbers being used. The uncritical adoption of these tests gives undue credence to the assertion that shark attack incidents and fatalities are increasing for any reason other than chance alone.

2. Basing a decision to take action to minimise shark attacks due to the economic effects on one-off anecdotal reports of a drop people learning to scuba dive is inadequate justification.

3. Allowing the program will not provide any extra information as suggested in the approval as the same methods are already being used elsewhere.

4. There is a significant problem non-targeted species, a large portion of which are threatened species, being detrimentally affected by the program.

5. Given all the above, the issue must fall well below the minimum criteria to be considered ‘in the National Interest’.





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