Semi-intensive commercial yabby farming produces quantities of yabbies at far higher densities than occurs naturally in the wild. Ponds are built to specifications that suit the yabbies, shelter is added and food is supplied. All this is inducive to growing large numbers of yabbies quickly.
Now the yabby Cherax destructor is one of the few species on this planet that is increasing its area of domination. I know you can google it and the International Union for the Conservation of Nature Red List shows the species as vulnerable but that’s not the case. Yabbies are a robust species with an instinct to wander and distribute. They are a migrating species and can migrate on mass. It’s extremely easy and common at night when you get a bit of rain to have yabbies leave the pond they are in, and go a wondering all over the place. They can travel long distances overland and survive for days in wet grass. The larger the yabbies and the higher the density of yabbies in your pond, the greater the chances of wondering occurring.
Perimeter fencing of your ponds is essential for semi intensive production of yabbies, you don’t want them to wander from the pond.
There are a number of choices for perimeter fencing (you can see more options in The Commercial Yabby Farmer book) but this article is on a fence use in a high fire risk area.
This article is based on a property that adjoins a state forest that is subject to regular bushfire so the metal fencing has the benefit of being fire proof compared to say “silt stop barrier” or “poly” fences.
0.48mm Trimdek or equivalent roofing sheets (many crayfish farmers use corrugated iron).
40 mm x 0.55 mm Top Hat Battens
Hex head Screws
Full 6 metre sheets of trimdeck are purchased and this farmer cut them in half down the middle with a hand grinder. This gives you two sheets roughly 400 mm wide. Normally farmers would not cut the sheet in half but use the full sheet. Top hat battens are cut at 750 mm lengths to suit the half width sheets.
As a consultant I recommend “poly” fences and that you bury at least 100 mm in the ground. Please note that most State Fisheries Departments have a mandatory requirement that the perimeter fence is “imbedded in the ground”. They also usually have a min height requirement (typically 600 mm high)- please check the regulations before you do anything.