Australia is home to the only mass cuttlefish gathering in the world. This year these giants didn’t return
By late June, the animals should be well and truly aggregating. In short, the cuttlefish have simply failed to turn up.
Every winter, the Point Lowly coastline in South Australia hosts a remarkable sight: over 100,000 giant Australian cuttlefish gather to mate. This is the only known cuttlefish aggregation in the world, and it is a rare natural phenomenon listed on Australia's National Heritage register. Cuttlefish are the largest cephalopods, a group that also includes octopuses, squids, and nautiluses, and are found only in southern Australia.
This year, however, the cuttlefish have not returned to the Point Lowly aggregation site. Tourism operators reported significantly reduced numbers of cuttlefish, with only a handful seen per dive, far below the typical 100 or more.
The decline in cuttlefish numbers is unprecedented, even compared to a record low in 2013 when thousands of cuttlefish were still present. Various hypotheses have been proposed for the cause of this decline, including a massive algal bloom in the region dominated by Karenia cristata microalgae, and reduced prey availability due to changes in water temperature.
The algal bloom could have directly affected the cuttlefish or reduced their food supply, as cephalopods are carnivorous and rely on live food. However, winter water temperatures have been relatively warm, so temperature alone may not be the sole factor.
Despite the mystery surrounding the decline, some conservation measures have been taken. A 90-day tourism ban was imposed, giving the remaining cuttlefish the best possible chance to thrive. Invertebrates Australia is also convening a working group to review the population's conservation status on the IUCN Red List. While the exact cause of this year's cuttlefish absence remains unknown, ongoing research and conservation efforts may help protect these unique creatures for future generations.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
