Dive Log inc Sportdiving

Giant Spider Crab Aggregation IT’S that time of year again in Melbourne's Port Phillip Bay. The annual Giant Spider Crab aggregation has come and gone for 2019 - with a difference. T HE phenomenon is well known, tens of thousands of crabs march in unison to shallow waters where they moult their shells, grow larger and return to deeper water. For many years this incredible natural event has been enthusiastically observed by divers, snorkelers and onlookers from above and below the surface. When spider crabs moult their shells they are extremely By Steven Walsh & Naomi Strong PORT PHILLIP BAY, VICTORIA

vulnerable for about an hour until the new shell has hardened. This attracts natural predators like sting-rays, small sharks and even the odd cormorant. The difference this year has been an influx of another predator. Humans. As underwater photographers, we navigated around dozens and dozens of crab nets hauling in huge numbers of crustaceans. It was distressing. It raised a lot of questions. How much do we know about Giant Spider Crabs and this unique event? Are current fishing regulations sustainable? Will the amount of fishing actually make a dint in the large crab

The crabs were photographed and filmed by excited divers day and night. Image Naomi Strong

Naomi Strong filming the 2019 aggregation at Blairgowrie Pier. - Image Steven Walsh

The crabs were six or more deep in some places - Image Naomi Strong Below: A Cormorant on the hunt - Image Steven Walsh

| DIVE LOG Australasia inc. Sportdiving Magazine | SEPTEMBER 2019 | ISSUE 374 | www.divelog.net.au 30

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