This got me thinking- what is living in the Canning River that runs through the Cannington, Thornlie and Riverton area all the way through Shelley to Mount Pleasant? Do we have marron up here?
Being a freshwater crayfish, they live in the streams and fresh water catchments in the southwest of WA, particularly Harvey through to Albany. The following map from the Aquaculture Council of WA shows the distribution in the south west region of WA and gives a good illustration of the distribution. You can see that although we have them in our Canning River, it is as a result of seeding or human intervention that has seen their population spread north to the metropolitan water catchments.
While their natural predators are native water rats (seen below) and birds, they are heavily sought after and often illegally fished by humans due to their meaty bodies and are considered a delicacy. I found the following image on PerthNow of a rakali or native water rat that was part of the population of rats in the northern suburb of Madeley. Weighing between 600g-800g you can imagine how they could take on a marron, claws and all!
In 2011 following rain that washed sewerage into the Canning River, there was great concern for the welfare of the marron and fish due to the contaminated waters. According to the linked ABC News story, Fisheries WA were trying to intervene to save the marron who were fleeing the waters they call home.
ABC News; River Warning 2011
This shows that we do indeed have marron living in the waters that pass through our town and they are very sensitive to the impact of human population of the surrounding areas.
A similar story from 2010 saw the Canning River contaminated with pollutants and oxygen demanding organic matter. In this case the marron fled the Canning River in hoards and were assisted to relocate to a nearby creek.
In My Community; Marron Flee Fall in Oxygen Levels 2010
There are severe restrictions on the fishing of marron to protect the populations. A license is required and there are minimum sizes that can be taken, limits on the volume per fishing trip, specific methods of fishing and many other guidelines that are enforced by Fisheries WA. Even when I bought them I was warned to keep the receipt as proof that hadn't helped myself to them from the waters.
So while we may not see them, they are certainly there! Delicious as they may be, they are more than a meal and require a healthy environment to survive!
This has certainly made me think more about "what lies beneath". These charming little creatures battling not only their natural predators, but the impact of human settlement and the influence we have on the health of our rivers and waterways. So lets all be kind to the beautiful rivers we are blessed with!
Forever 6108!
Department of Fisheries WA
http://www.fish.wa.gov.au/Species/Marron/Pages/default.aspx
Aquaculture Council WA
http://www.aquaculturecouncilwa.com/how-to-get-into-aquaculture/species/marron/marron
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