Giant Spider Crab Migration Melbourne


About the Giant Spider Crab Migration in Melbourne

Come dive Rye or Blairgowrie Pier and experiance this wounderfull event

Melbourne’s Unique Marching Sider Crabs

Giant Spider Crabs (Leptomithrax gaimardii) are commonly sighted as they gather in there masse on the sandy bottom of Port Phillip, Melbourne, Most of the time the spider crabs head to Blairgowrie Marina and Rye Pier on the Mornington Peninsula in Victoria.

Once a year in Australia the spider crabs congregate in their thousands together for protection while moulting their outer shells and therefore exposing their soft bodies, This makes a great meal for Stingrays, Seals, Port Jackson sharks, and Birds. The migration usually only lasts a few weeks. If you want to dive with the Melbourne spider crabs the best time is around the Lunar cycles and the full moon between the end of May and the start of June.

Spider crabs converge like this at several locations in Australia – including in South Australia and Tasmania – but no aggregation is as predictable or easily accessible as that in Port Phillip.

This is a great event for people to watch on from the pier, go scuba diving or jump in for a snorkel and some freediving.

Giant spider crab facts

Giant spider crabs are Victoria’s largest growing spider crabs.
They can reach 16 cm across their carapace or shell, and 70 cm across their legs – although most are not this big.

These crabs are a native species and can be found in marine water across south-eastern Australia, commonly in shallow waters but down to 820m deep.

Giant Spider Crabs gather in huge groups at certain shallow water locations during winter each year. Scientists currently believe that the crabs move in from deeper waters and gather to find ‘safety in numbers’ while they moult.
Recently there has been a regular Giant Spider Crab aggregation each winter in the area of Blairgowrie and Rye piers. This is a wonderful natural asset in Port Phillip Bay which is popular and accessible. Enjoyment of the Giant Spider Crab aggregation is shared by recreational fishers, divers, and tourists. It provides a window to study the crabs and their behaviour.

Spider Crabs New Threats

In March in 2019, a new threat to the natural event in Port Phillip emerged. As an unprecedented number of crab fishers flocked to Blairgowrie, using baited crab traps from the pier there.

Under Victorian fisheries legislation, it is illegal to catch more than “30 crabs or 1 liter of whole or parts of crabs” outside protected areas. A fisher can catch them in water deeper than 2m, by hand, spear, or by using up to two bait traps or up to 2 hoop nets.

The Spider Crab Alliance was formed to highlight community concerns and provide a platform for sharing these with governing bodies. A petition calling for a halt to spider crab fishing during the migration and to lower bag limits has since continued to grow. The aim of the petition is to achieve change in a respectful and constructive manner for the best outcome possible for the crabs and for the thousands of local, national, and global enthusiasts who travel from around the world to witness the annual event.

Your observations are important

Natural history observations by the many divers, snorkelers, fishers, and beachgoers who value giant spider crabs will continue to be an important and valuable resource.

This year, the VFA is inviting recreational divers to assist us with some Giant Spider Crab information while doing your normal recreational dives. We will bring together the information that you share with us and collate it at an aggregated scale. Updated fact sheets will be posted on our webpage as knowledge of Giant Spider Crabs grows.

Click to report where you see Giant Spider Crab 

Click to register with the VFA to collect Giant Spider Crab moults for further research

Fisheries Size and bag limits

The fishing rules for Giant Spider Crabs are the same as those for all crab species except European green shore crabs.

There is no minimum size limit.

The bag limit is a total of 1 liter or a combined total of 30 whole or parts of crab from one or more species.

This is the total number of crabs you can collect and keep each day. It includes Giant Spider Crabs and any other species of crab that you collect.

You can’t collect crabs in waters less than 2 meters deep (the intertidal zone) in Port Phillip Bay. Click here for more information on Port Phillip Bay’s intertidal zone.

You can’t collect crabs in Marine National Parks and Sanctuaries. Click here for more information on Marine National Parks and Sanctuaries.

Outside of restricted areas, the only methods you can use to collect crabs in marine waters are:

Outside of restricted areas, the only methods you can use to collect crabs in marine waters are:

  • by hand
  • by a spear (but not within 30 m of piers or jetties)
  • by using up to 2 bait traps
  • by using up to 2 hoop nets (Note: The closed season for hoop nets is from 15 September to 15 November every year. During this time, hoops nets can only be used in Port Phillip Bay, Western Port Bay, the Gippsland Lakes, and any other inlet)

The number, size, and shape of the equipment used are important. It is also important that your equipment is appropriately labelled. Click here for a summary of the fishing gear that can legally be used in Victoria, and how to use it.

Remember, collecting for other people contributes to your bag limit.

Fisheries officers will be out and about during this year’s Giant Spider Aggregation, if it occurs, at Rye / Blairgowrie pier. They will be monitoring the aggregation and checking compliance with the fishing rules using overt and covert patrols.