TWEETING SHARKS WARN BEACHGOERS THEY’RE NEAR
Depending on your age and predicament, you might have been either happy or worried when your mom joined the world of social media. Whether you’re ecstatic to share little Burt’s tenth portrait of the day or you find yourself frantically deleting evidence of that party you went to, your mom – and maybe even your grandma – are there to stay. Social media is now the norm and the whole world is on it. Yet social media has even more surprises for us: it’s crossing the species boundary. No, not just pets, but predators too: Sharks living off the coast of Western Australia have just joined Twitter. “Surf Life Saving WA” is a Twitter account that aims to protect beachgoers and has amassed over 31,000 followers so far. The ‘tweets’ include summaries of first aid assists, pictures of brave rescues on the water, and tweets from the local sharks: “Fisheries advise: tagged Tiger shark detected at Warnbro Sound receiver at 06:14:00 PM on 13-Feb-2014” Yes, you read that right: sharks that tweet. According to their website, the Department of Fisheries in Western Australia has tagged 326 sharks – including Great Whites, Whaler and Tiger Sharks – with acoustic transmitters. When a tag is then detected by one of the 320 or so acoustic receivers in the water, a tweet is sent out. This program was set up in response to the high number of fatal shark attacks in Western Australia in recent years, including six in the past two years alone. But Dr. Rory McAuley, principal research scientist with the Department of Fisheries, says that the tagging program isn’t just to help beachgoers stay safe: it also contributes to important shark research. So far, the tag-to-tweet program has done a great job of alerting people to nearby sharks. The one obvious snag, however, is that not
all sharks are tagged. Sharks can swim vast distances: one tagged Great White named “Nicole” traveled an amazing 20,000 km from Africa to Australia in 2005. It’s likely that many sharks in the waters of Western Australia are only temporary visitors, making it all but impossible to tag every one. But it’s a good start, and shark-sympathisers much prefer it to the recent government culling program, which set out to kill any sharks over 3 meters long. According to the website SupportOurSharks.com, over 100 shark experts and 33,000 others have spoken out against the culling. ( You can see their letter here.) As a top predator, sharks are ‘keystone species’ – they have a very important effect on the community around them. If, for example, sharks weren’t there to eat sea turtles and dugongs, their populations would increase; all those extra hungry mouths to feed would lead to an over-grazing of sea grass. (Of course, this example assumes these populations would experience no human interference – something of a vain hope given that both sea turtles and dugongs are classified as ‘vulnerable’ at best and ‘critically endangered’ at worst.) As sea grass provides habitat and food for many species, losing it would have far-reaching effects. In this way, and in countless others, sharks are vital to the health of the oceans. Sharks help to keep the system in balance. Ultimately, this shark tagging programme may help establish a healthy balance between sharks and surfers. But in the meantime, don’t forget to check your Twitter feed because at least some of them will tweet a hello when they’re around.
Find out more:
• The International Union for Conservation of Nature and Natural Resources Red List
• Carcharodon carcharias (Great White Shark) • Galeocerdo cuvier (Tiger Shark)
• Carcharhinus amblyrhynchos, Blacktail reef shark
• Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks
ABOVE: Researchers tagging a shark.
ABOVE: An acoustic transmitter, used to track the shark’s movements.