Maron fishing in Western Australia is regulated by the Department of Fisheries and there are strict bag limits and restrictions on where can be fished to ensure that ovefishing does not occur. There are several important things to remember:

Location: Most rivers in the South West of WA are marron waters, including the Warren, Donnelly, Blackwood, Moore, and Hutt Rivers; the Deep, Gardiner, Capel and Preston Rivers and their tributaries; the Murray River (upstream from the Pinjarra weir); and the Collie River (upstream of the Australind Bypass).

Size: A minimum legal size limit of 80 mm carapace length applies throughout the marron fishery except in ‘Trophy Waters’ where a minimum size limit of 90 mm applies. (Guages are available from most camping stores but often sell out quickly just before the season as you would expect.)

Bag Limits: A daily bag limit of 10 marron per licensed fisher applies except in ‘Trophy Waters’ where a bag limit of five applies. The daily bag limit
applies from midday to midday the next day during the open season.

Full details are available here.