Every winter, a sliver of the South Australian coast hosts the world’s largest mating occasion for giant cuttlefish.
Some years, tons of of 1000’s of the distinctive marine species endemic to Australia collect along the Cuttlefish Coast for the annual mating season, bringing their vibrant, shape-shifting figures to the shallow waters and attracting 1000’s of eager divers.
But this yr, the turnout was the lowest on file, sparking considerations of a “catastrophic decline” of the species.
Official figures launched this month estimate just 1,811 cuttlefish turned up to mate this yr, down from 63,000 last yr – a 97% drop.
The state authorities says a poisonous algal bloom that has ravaged the state’s shoreline for more than 18 months may be to blame for the sharp decline.
The low figures have also prompted calls for the species to be listed as endangered.
Adult cuttlefish usually die after breeding so each mating season is essential for the species’ future, but in latest months, just 440 eggs have been counted, instead of the tens of millions that are normally laid.
Manny Katz, 28, was one of 4 divers who spent hours along the coast last month to observe the annual breeding occasion, having been tasked by South Australia’s Department of Environment and Water (DEW).
“Because there have been so few cuttlefish, DEW thought it would be worth going out and trying to do an assessment of how many eggs there currently are around the coastline to understand what the population is going to be next year.”
Over two days in July, his workforce did eight one-hour dives, exploring the undersides of rocky reefs to depend the eggs.
“Along the eight kilometres (five miles) of coastline, there would normally be millions of eggs,” he said, as each feminine can lay dozens of egg and tens of 1000’s normally flip up to breed.
“[We] pretty much looked under every single rock that we could have and we only found about 440 eggs.”
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