Personal deterrents can reduce the risk of shark bites

19 06 2018
Shak deterrent testing

Photo: Charlie Huveneers

A little over a week ago, shark ecologist, Charlie Huveneers, and I attempted to write an article in The Conversation about a report we co-wrote regarding the effectiveness of personal shark-deterrent devices (see below for more on the report itself). It’s a great little story, with both immediate policy implications for human safety and great, big potential improvements to shark conservation in general (i.e., if sharks kill fewer people, then perhaps governments would be less inclined to invokes stupid laws to kill sharks). Indeed, sharks aren’t doing very well around the world, mainly because of over-harvest and persecution from unfounded fear.

Anyway, all was going swimmingly until our editor at The Conversation suddenly decided that they wouldn’t publish the piece based on the following funding disclaimer that we had submitted with the article:

This project was funded by the New South Wales Department of Primary Industries Shark Management Strategy Competitive Annual Grants Program, the Government of South Australia, Ocean Guardian Pty Ltd, and the Neiser Foundation. We openly and transparently declare that Ocean Guardian contributed financially to the study, but that Ocean Guardian was not involved in the study design or implementation, nor did they have access to the data post-collection. Nor did Ocean Guardian provide input into data analysis, interpretation, writing of the report, or the conclusions drawn. The study design followed a protocol developed for a previous study, which was not funded by Ocean Guardian. In summary, Ocean Guardian had no opportunity to influence any aspect of the study or its conclusions, apart from providing some financial support to realise the field project (e.g., boat hire, equipment purchase, etc.) in the same manner as the other funding agencies. The South Australian cage-diving industry provided logistical support during the testing of the deterrents.

The long and short of The Conversation‘s negative decision was that one of the companies contributed financially to project. However, as we stated above, they had absolutely no influence in the subsequent experimental design, data collection, analysis, interpretation or report writing.

While normally I’m a big fan of The Conversation, I really think they dropped the ball with this one. Their decision was illogical and unsupported for five main reasons:

  1. There were many funding partners involved, and the Ocean Freedom contribution was in no way the major or even majority share of funding.
  2. Other companies with devices tested could have contributed, but only Ocean Freedom offered.
  3. The study was commissioned by a state government agency (New South Wales Department of Primary Industries), which is not a commercial entity.
  4. As stated in our disclosure, there was no opportunity for manipulating experimental design, data ownership, or post-collection analysis or writing that could have influenced the results, by any funders or contributors.
  5. The disclosure is open, honest, comprehensive and in every way truthful.

So, I’m more than just a little disappointed — and my opinion of the organisation has dropped considerably. That, with the constant barrage of donation requests they send makes me think twice about their journalistic integrity. I challenge others to think carefully before giving them any money.

Regardless, let’s move on to the article itself (which I can publish freely here without the Draconian oversight of The Conversation):

Many things might explain why the number of shark bites appear to be increasing. However, the infrequent occurrence of such events makes it nearly impossible to determine why. Recently, an atypically high rate of shark bites occurred in Western Australia in 2010-2011 and on the north coast of New South Wales in 2015-2016. These highly publicised events — often sensationalised in both traditional and social media — have pressured governments to implement new measures to reduce the risk of shark bites.

The rising pressure to do something to reduce shark bites has prompted the recent development or commercial release of many new personal shark deterrents. Yet, most of these devices lack any rigorous scientific assessment of their effectiveness, meaning that some manufacturers have made unfounded claims about how much their devices dissuade sharks from attacking humans.

However, if a particular type of commercially available shark deterrent happens to be less effective (or completely ineffective) as advertised, it can give users a false sense of security, potentially encouraging some to put themselves at greater risk than is necessary. For example, some surfers and spearfishers probably ignore other mitigation measures, such as beach closures, because they ‘feel safe’ when wearing these products.

Read the rest of this entry »

Greater death rates for invasive rabbits from interacting diseases

30 05 2018

When it comes to death rates for invasive European rabbits (Oryctolagus cuniculus) in Australia, it appears that 1 + 1 = 2.1.

Pt tagged rab with RHD+myxo 1 10-08

Tagged European rabbit kitten infected with myxoma virus, but that died from rabbit haemorrhagic virus disease (RHDV). Photo by David Peacock, Biosecurity South Australia.

“Canberra, we have a problem” — Sure, it’s an old problem and much less of one than it used to be back in the 1950s, but invasive rabbits are nonetheless an ecological, conservation, and financial catastrophe across Australia.

relative rabbit abundance South Australia

Semi-schematic diagram, redrawn using data from Saunders and others and extended to include the recent spread of RHDV2, showing changes in rabbit abundance in relation to the introduction of biological control agents into north-eastern South Australia. Dotted lines indicate uncertainty due to lack of continuous annual data. The broken line indicates a level of about 0.5 rabbits ha-1, below which rabbits must be held to ensure recovery of native pastures and shrubs (from B. Cooke 2018 Vet Rec doi:10.1136/vr.k2105)

Rabbits used to reach plague numbers in much of agricultural and outback Australia, but the introduction and clever manipulation of two rather effective rabbit-specific viruses and insect vectors — first, myxoma virus in 1950, European rabbit fleas in the 1960s to help spread the virus, then Spanish rabbit fleas in the 1990s to increase spread into arid areas, and then rabbit haemorrhagic disease virus (RHDV) in 1995 — have been effective in dropping rabbit abundances by an estimated 75-80% in South Australia alone since the 1950s.

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Tiny, symbiotic organisms protect corals from predation and disease

20 12 2017
hydrozoan polyp

Hydrozoan polyps living on the surface of a coral (photo credit: S. Montano)

Corals could have some unexpected allies to cope with the multi-faceted threats posed by climate change.

In a new study published today in Proceedings of the Royal Society B, Montano and colleagues show how tiny hydrozoans smaller than 1 mm and commonly found in dense colonies on the surface of hard corals (see above photo) play an important ecological role.

Visually examining ~ 2500 coral colonies in both Maldivian and Saudi Arabian reefs, the scientists searched for signs of predation, temperature-induced stress, and disease. For each colony, they also recorded the presence of symbiotic hydrozoans. They demonstrated that corals living in association with hydrozoans are much less prone to be eaten by corallivorous (i.e., ‘coral-eating’) fish and gastropods than hydrozoan-free corals.

A likely explanation for this pattern could be the deterring action of hydrozoan nematocysts (cells capable of ejecting a venomous organelle, which are the same kinds found in jellyfish tentacles). An individual hydrozoan polyp of less than 1 mm clearly cannot cope with a corallivorous fish that is a billions of times larger, yet hydrozoans can grow at high densities on the surface of corals (sometimes > 50 individuals per cm2). This creates a sort of a continuous, ‘urticating‘ carpet that can discourage fish from foraging. Read the rest of this entry »

Two new postdoctoral positions in ecological network & vegetation modelling announced

21 07 2017


With the official start of the new ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH) in July, I am pleased to announce two new CABAH-funded postdoctoral positions (a.k.a. Research Associates) in my global ecology lab at Flinders University in Adelaide (Flinders Modelling Node).

One of these positions is a little different, and represents something of an experiment. The Research Associate in Palaeo-Vegetation Modelling is being restricted to women candidates; in other words, we’re only accepting applications from women for this one. In a quest to improve the gender balance in my lab and in universities in general, this is a step in the right direction.

The project itself is not overly prescribed, but we would like something along the following lines of inquiry: Read the rest of this entry »

Noses baffled by ocean acidification

18 04 2017

Clown fish couple (Amphiprion percula) among the tentacles of anemone Heteractis magnifica in Kimbe Bay (Papua New Guinea) – courtesy of Mark McCormick. Clownfish protect anemones from predators and parasites in exchange of shelter and food. The fish tolerates the host’s venom because its skin is protected by a mucus layer some 2-3× thicker than phylogenetically related species (12); clownfish fabricate the mucus themselves and seem to obtain anemone antigens through a period of acclimation (13), but whether protection is acquired or innate is still debated. Clownfish are highly social bony fish, forming groups with one reproductive pair (up to 11 cm in length each) and several smaller, non-reproductive males. Reproduction is protandrous (also known as sequential hermaphroditism), so larvae are born male and, as soon as the reproductive female dies, her widower becomes female and the largest of the subsidiary males becomes the alpha male. The IUCN lists clownfish, generically named ‘anemone fish’, as threatened by the pet-trade industry and habitat degradation, although surprisingly, only 1 species has been assessed (A. sandaracinos). The clown anemone fish A. ocellaris is the species that inspired Nemo in the 2003 Academy-Award fiction movie – contrary to the logical expectation that the Oscars Red Carpet would generate support for conservation on behalf of Hollywood, of the 1568 species represented in the movie, only 16 % of those evaluated are threatened (14).

Smell is like noise, the more scents we breathe in one sniff, the more difficult it is to distinguish them to the point of olfactory saturation. Experimental work with clownfish reveals that the increase in dissolved carbon dioxide in seawater, mimicking ocean acidification, alters olfactory physiology, with potential cascading effects on the demography of species.

Places such as a restaurant, a hospital or a library have a characteristic bouquet, and we can guess the emotional state of other people by their scents. Smell is critical between predators and prey of many species because both have evolved to detect each other without the aid of vision. At sea, the smell of predators dissolves in water during detection, attack, capture, and ingestion of prey, and many fishes use this information to assess the risk of ending up crunched by enemy teeth (1, 2). But predator-prey interactions can be modified by changes in the chemical composition of seawater and are therefore highly sensitive to ongoing ocean acidification (see global measuring network here). Experts regard ocean acidification as the ‘other CO2 problem’ of climate change (3) — just to emphasize that anthropogenic climate-change impacts terrestrial and aquatic ecosystems alike. Acidification occurs because the ocean absorbs CO2 at a rate proportional with the concentration of this gas in the atmosphere and, once dissolved, CO2 becomes carbonic acid (H2CO3), which in turn releases protons (H+) — in simple terms, pH is the concentration of protons (see video about ocean acidification): Read the rest of this entry »

To feed or to perish in an iceless world

1 02 2017

Emaciated female polar bear on drift ice in Hinlopen Strait (Svalbard, Norway), in July 2015 – courtesy of Kerstin Langenberger (

Evolution has designed polar bears to move, hunt and reproduce on a frozen and dynamic habitat that wanes and grows in thickness seasonally. But the modification of the annual cycle of Arctic ice due to global warming is triggering a trophic cascade, which already links polar bears to marine birds.

Popular and epicurean gastronomy claims that the best recipes should use seasonal veggies and fruits. Once upon a time, when there were no greenhouses, international trade routes, or as much frozen and canned food, our grandparents enjoyed what was available at the time. So in some years we had plenty of cherries, while during others we might have feasted on plums. Read the rest of this entry »


24 02 2016

frogWhile I’ve blogged about this before in general terms (here and here), I thought it wise to reproduce the (open-access) chapter of the same name published in late 2013 in the unfortunately rather obscure book The Curious Country produced by the Office of the Chief Scientist of Australia. I think it deserves a little more limelight.

As I stepped off the helicopter’s pontoon and into the swamp’s chest-deep, tepid and opaque water, I experienced for the first time what it must feel like to be some other life form’s dinner. As the helicopter flittered away, the last vestiges of that protective blanket of human technological innovation flew away with it.

Two other similarly susceptible, hairless, clawless and fangless Homo sapiens and I were now in the middle of one of the Northern Territory’s largest swamps at the height of the crocodile-nesting season. We were there to collect crocodile eggs for a local crocodile farm that, ironically, has assisted the amazing recovery of the species since its near-extinction in the 1960s. Removing the commercial incentive to hunt wild crocodiles by flooding the international market with scar-free, farmed skins gave the dwindling population a chance to recover.

redwoodConservation scientists like me rejoice at these rare recoveries, while many of our fellow humans ponder why we want to encourage the proliferation of animals that can easily kill and eat us. The problem is, once people put a value on a species, it is usually consigned to one of two states. It either flourishes as do domestic crops, dogs, cats and livestock, or dwindles towards or to extinction. Consider bison, passenger pigeons, crocodiles and caviar sturgeon.

As a conservation scientist, it’s my job not only to document these declines, but to find ways to prevent them. Through careful measurement and experiments, we provide evidence to support smart policy decisions on land and in the sea. We advise on the best way to protect species in reserves, inform hunters and fishers on how to avoid over-harvesting, and demonstrate the ways in which humans benefit from maintaining healthy ecosystems. Read the rest of this entry »