Burrowing Crayfish

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Another "just back from..."

This time it’s just back from conducting a Burrowing Crayfish (Engaeus spp.) survey at Warburton, Victoria.

Aquatica was thrilled to be asked by the EcoLink team to undertake the survey for one of their clients.

Aquatica designed and built the ‘modified ‘Norrocky’ burrow traps based on the original design by Norrocky (1984, for catching north American species of burrowing crayfish), modifications developed by Arthur Rylah Institute’s (ARI) team (Bryant et. al. 2012) and a few of our own design ideas.

Thirty traps were deployed overnight across a number of burrow sites and three crayfish were caught.  The 10% catch rate was roughly inline with ARI’s average result for a modified Norrocky trap (Bryant et al 2012) and a great result given the seasonal timing was not ideal.  Its likely recent rains in the Warburton area, meant many of the burrows had active crayfish undertaking repair works before slowing down for the winter.

Similarly as has been experienced by most using the Norocky-style traps, they are prone to failure when the burrow’s resident crayfish jams the trapdoor open or closed with mud.

It's very challenging keying Engaeus to species level.  The primary key we used was the key developed by Pierre Horwitz (Horwitz 1990).  At this stage we have keyed the three specimines out to that of E. affinis,  a common species in the Warburton area and not listed as threatened.  However, we have sent specimine macro photographs to ARI for confirmation of that ID.

The images below are of the three specimines we caught, with the first two being large males and the final a female.

A great image showing one of the large males giving the camera the 'angry claws' stance.

Trapdoor mechanislm in the trap showing its simple design and then one plugged up with mud by the resident crayfish

 

References

Bryant, D., Crowther, D., Papas, P. (2012). Improving survey methods and understanding the effects of fire on burrowing and spiny crayfish in the Bunyip and South Gippsland catchments. Black Saturday Victoria 2009 – Natural values fire recovery program. Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, Heidelberg.

Horwitz, P. (1990). A Taxonomic Revision of Species in the Freshwater Crayfish Genus Engaeus Erichson (Decapoda: Parastacidae). Invertebr. Taxon., 1990, 4, 427-614.

Norrocky, M.J. (1984). Burrowing crayfish trap. Ohio Journal of Science 84, 65–66.