<?xml version="1.0" encoding="ISO-8859-1"?> <docID>340403</docID> <postdate>2025-03-15 08:59:53</postdate> <headline>Explosion in croc numbers triggers feral feast fallout</headline> <body><p><img class="size-full wp-image-340404" src="https://citynews.com.au/wp-content/uploads/2025/03/20250313144194226401-original-resized.jpg" alt="" width="900" height="601" /></p> <caption>For every kilometre of NT river, there are 25 times more crocodiles than there were 50 years ago. (Dean Lewins/AAP PHOTOS)</caption> <p><span class="kicker-line">By <strong>Abe Maddison</strong></span></p> <p><strong>Northern Australia's massive crocodile population is munching its way through huge numbers of feral pigs, with the apex predator's changing diet having a significant impact on the environment.</strong></p> <p>Since they were protected in 1971, croc numbers in the Top End have exploded 25-fold from one every five kilometres of river to more than five per kilometre.</p> <p>In terms of biomass, or the collective bulk, of the largest and some would argue most misunderstood reptile on the planet, that represents a whopping increase from less than 10kg per kilometre to 400kg.</p> <p>Researchers have studied data from eight Northern Territory river systems and found the prehistoric predators are eating nine times as much as they did in 1979, with a major shift in diet from fish to wild pigs and water buffalo.</p> <p>"They're excreting all those nutrients in the water and this has also led to significant nitrogen and phosphorus input into the ecosystem," Charles Darwin University research lead Hamish Campbell said.</p> <p>"We don't really know what the impact is yet but it's significant. It's really large.</p> <p>"If you look at how much they're eating, what they're eating and where they're excreting their waste products, the effects have to be pretty significant."</p> <p>"It might be that it's great for barramundi but we just don't know yet."</p> <p>The research, published in the Proceedings of the Royal Society B journal, is part of a larger study assessing the impact of crocodiles on the north Australian freshwater ecosystem.</p> <p>The Top End's estimated 100,000 crocodiles are devouring as many as six feral pigs per square kilometre of wetland annually.</p> <p>This "landscape of fear" has had a significant impact on the pigs' behaviour, Prof Campbell said.</p> <p>"If you're a pig in the 1960s or a buffalo, you could just wallow in those water holes to your heart's content and feed but now you can't do that because you're going to get eaten.</p> <p>"Whilst we don't have any evidence the crocs are managing feral pigs, because the pigs reproduce up to 50 piglets a year, I do imagine that without crocs, the level of damage would be much more severe from pigs and feral cattle and buffalo."</p> <p>While the ongoing crocodile population boom often leads to talk of culling, Prof Campbell was quick to dismiss it.</p> <p>"Culling is an emotive argument, it's a straw man," he said.</p> <p>"You cannot make culling decisions based around ecological data.</p> <p>"It doesn't matter if you've got 10 crocodiles in a water hole or one crocodile in the water hole, you still wouldn't swim there, would you?</p> <p>"You're still going to die whether it's one crocodile or 10 crocodiles that eat you. The only way to stop crocodile attacks is to kill all crocodiles."</p> <p>And a lot of people actually like crocodiles, he said.</p> <p>"They're a source of employment for a lot of indigenous people; they're an indigenous totem and a lot of tourism comes to the territory because of crocodiles, so we're not going to go back to that state of all-out war on crocodiles like we did in the '70s."</p> <p>The next research step is to study the impact of crocodiles on vegetation.</p> <p>"So we're looking at sediment cores because we're trying to go back in time to look at what the ecosystem was composed of and during different crocodile (population) densities," Prof Campbell said.</p> <p>"And then we're using satellite (data) to try to look at how vegetation has changed over the last 20-30 years."</p> </body>