Warm Waters on the Move: Australia’s Marine Life Journey Southwards

As we feel the crisp, cool air on our faces during the Australian winter, we might be surprised to find that our ocean waters are not following suit. Take a dive in the sea, and you’ll notice that the water feels warmer than usual. Try casting your fishing line off Sydney, and you may reel in a tropical coral trout. It’s an odd sight, but it signifies a new reality: our waters are heating up. And it has our marine life moving south.

What is the cause?

The culprit? Climate change. The oceans have absorbed the lion’s share of the extra heat trapped by carbon dioxide and other greenhouse gases. As a result, heat in our oceans is accelerating rapidly. In fact, this year’s temperature readings are unprecedentedly high, with coastal waters predicted to be up to 2.5℃ warmer than usual in many locations, even without the warming impact of an El Niño event.

This drastic rise in temperature has triggered a mass migration amongst our marine life. At least 200 marine species in Australia have moved from their original habitats since 2003, with 87% journeying south. This disruption to marine species’ habitats is not isolated to Australia; it’s a global phenomenon. This year, Australia’s winter seascapes are likely to resemble our summer seascapes due to the warmer ocean temperatures.

Which species are being impacted?

So, which of our marine friends are on the move?

1. The vibrant Moorish idol is now moving south of Geraldton in Western Australia and Eden in New South Wales. This is far from its historical northern Australian range.
2. The pale pink branching coral, traditionally found in northern NSW, has been sighted south of Port Stephens. In turn creating new habitats for a variety of species including tropical fish and crabs.
3. The tasty Eastern rock lobster, once common in NSW, has now found new homes in Tasmania and even South Australia.
4. Gloomy octopus, commonly found in NSW, is now appearing as far south as Tasmania.
5. The slow-swimming whitetip reef shark has been spotted south of K’gari (formerly known as Fraser Island).
6. Even our gentle dugongs are not immune, migrating as far south as Shark Bay in WA and Tweed River in New South Wales. In 2014, a dugong was even reported at City Beach, Perth.
7. Warm water game fish, such as the red emperor, are appearing much further south, particularly in WA.
8. The long-spined sea urchin has found a new home in southern and western Tasmania.

Impact on us

The effects of this large-scale migration are not purely ecological but also have significant socioeconomic consequences. This is especially true for our coastal communities dependent on fisheries. The unpredictability of fish stocks in terms of abundance and geographical distribution complicates the task for fishers and puts additional strain on our fisheries.

As a nation, we can contribute to tracking this migration. Redmap, an Australian citizen science project, provides a platform for fishers, snorkellers, spearfishers, and the public to log unusual marine sightings. Your contribution could help scientists better understand the effects of climate change on our marine ecosystems.

The phenomenon of marine life moving south is a clear illustration of the extent of global warming’s effects. It serves as a stark reminder of the urgency of mitigating climate change to protect the balance of our uniquely Australian marine ecosystems. We must pay attention to this silent migration and act decisively against the accelerating pace of global warming.