Parting shot
The crocodile dilemma
IN JUNE 2014 a Darwin fisherman, Bill Scott, was snatched from a tinny by a crocodile in a billabong at Cooinda, in Kakadu National Park. Just two months later, Lanh Van Tran was killed when he waded into the Adelaide River to retrieve a snagged line. An inquest in 2015 found that because “crocodile populations have increased significantly” and “previously unknown hunting behaviours” have been observed, people must take extra precautions to avoid attacks.The inquest reignited a debate about culling crocodiles in the NT.
Northern Australia’s saltwater crocodiles have increased both in size and abundance since laws to protect them were introduced in 1969–74. In the NT, numbers have increased from about 4000 to 100,000.The population is stabilising, but the average size of crocodiles is still increasing. Trends of a similar nature have occurred in Queensland and Western Australia. Male salties reach recorded maximum lengths of 5.5m and weights of 800kg. Such massive crocodiles treat humans in the water or at its edge as natural food items, and attacks from crocodiles of more than 4m are nearly always fatal.
During the period these increases occurred, human populations in cities that intrude on crocodile habitat – such as Cairns and Darwin – increased. Crocodiles killed four people in the NT in 2014, almost one-fifth of the total 22 killed in the state since the species was protected. All up, 34 people have been killed by crocs in Australia since 1971.
Public and political responses to attacks vary by state and context: where, how and who was attacked. Not surprisingly, calls for culling are usually part of the response. But it is a compromise the public seeks, not eradication; they assume safety can be improved by reducing numbers, but not to the extent the species becomes threatened again.
The value of widespread culling comes down to how many crocodiles need to be removed to improve safety. People being attacked while swimming is the most common occurrence, despite ample warnings against it; fatal misadventures occur most often under the influence of alcohol and drugs.
To swim down any river with a large population of salties is to invite almost certain death. If 25 per cent were culled, it would still not be ‘safe’ – you might swim a little further, but you would still be killed. Furthermore, reducing numbers by 25 per cent is likely to stimulate population growth, leading to a larger number of crocodiles. If the population was reduced by 95 per cent to pre-protection levels, the probability of a fatal attack would be reduced, but swimming would remain dangerous.
But culling to this extent would not be acceptable on conservation grounds, neither here in Australia nor internationally. It would also not be acceptable on commercial grounds in the NT, because landowners sustainably harvest and sell crocodiles and eggs on private and traditional lands, and this would be undermined by culling.
However, strategic rather than blanket culling can be a very successful tool in overall management programs – one already in use. Any crocodiles that move into Darwin Harbour
(about 250 per year) are culled.The management goal is to make crocodiles extinct here, where the majority of Territorians live and where attacks are likely. Maintaining depleted populations in some spots alongside abundant populations in others is perhaps the only sensible approach to conserving this formidable predator.
As with wolves in the USA and sharks in Australia, conserving predators, and rebuilding populations, is always a management challenge. If conservation is a success and the populations grow, then predation rates increase, leading to calls for culling. In situations of human– wildlife conflict, strategic culling and sustainable harvesting are useful tools for maintaining the will for conservation.
In areas where crocodiles are numerous, and they are of value to landowners and tour operators, culling is unlikely to bring lasting benefits. In these places, people must learn to manage their behaviour to reduce risks, and education programs are essential.
For example, the attack on Bill Scott highlighted the need to publicise that low frequency sounds, from something as simple as filling a bucket with water, can attract crocodiles. Similarly, attacks on Aboriginal people resulted in an advertising campaign about safety in the context of traditional hunting.
I believe the key to living safely with crocodiles is adopting a management approach that adapts as needed to circumstances and locations, rather than looking upon widespread culling as a silver bullet.