Help needed in search for exotic crab from ballast water in Auckland/Tauranga.


Females with eggs of the exotic green crab Carcinus maenus  were recently found by Australian researchers in a ship which had recently arrived from Tauranga.   Staff of the CSIRO's Centre for Research on Marine Pests (Hobart) checked the ship in Tasmania.   It is unclear exactly where the green crabs originated from.

They may not be living in Tauranga yet, but we should be looking for them.

Another possible point of entry for these crabs is in the vicinity of Caliope dock in Auckland. is another spot which should Several years ago, a  Russian trawler had some 90 tonnes of foreign mussels removed fronm her hull while in dry dock there. The mussels were disposed of safely, but other organisms  such as the crabs may have escaped detection.  The ship had NZ waters for some eighteen months before she was cleaned.

We would like to contact crab fisherman in the vicinty of Auckland and Tauranga.   We would also like to find someone who is willing to set a crab pot or two in the vicinity of Caliope dock in Auckland.

Please email names and contact details to Tim Dodson, at Cawthron Institute.

The green crab is found all along the shores of Europe and as far south as Mauritanea. Since early last century  it has invaded numerous areas throughout the world including Eastern and western coasts of the US, South Africa, Victoria , Australia and lately Tasmania.

The green crab is an aggressive predator of juvenile bivalves, other small shellfish and marine animals. It has been implicated in the collapse of the soft shell clam industry on the East coast of the US in the 1950s and poses a possible serious threat to NZ's shellfish populations and fisheries, to say nothing of their possible impact on shellfish aquaculture.

The crab is highly adaptable, tolerating salinities from 4 to 35 ppt . It  breeds successfully in water with a salinity as low as 13ppt.and is are tolerant of wide variations in temperature; equatorial limits of 22 oC and polar limits as low as -1 to 0 oC. The upper temperature breeding barrier is reported as being around 18-26 oC. It seems capable of great adaption as regards to its habitat, being known from sheltered rocky shores, mudflats and tidal marshes.

For more information read the article in Seafood New Zealand, May 1997 page 13.
The title is "Ecosystem Transplant? The Case of the Yefim Gorbenko."

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