Traditional Aquaculture & Freshwater Fisheries Management

1. Hydrodynamic Principles of Bibbullmun Inland Aquaculture

The freshwater river systems and inland lake basins of southwest Western Australia supported sophisticated aquacultural management systems developed over thousands of years of continuous custodial occupancy.¹ Bibbullmun hydrologists and ecological engineers understood the hydrodynamic behavior, breeding seasons, and migration patterns of endemic freshwater fauna—most notably the freshwater cobbler (Tandanus bostocki), nightfish (Bostockia porosa), western minnow (Galaxias occidentalis), and freshwater decapod crustaceans such as marron (Cherax cainii), koonac (Cherax preissii), and gilgie (Cherax quinquecarinatus).² Rather than passive riverbank fishing, customary management relied upon permanent and semi-permanent earth and stone raceways, wooden brush traps, and artificial holding pools that transformed natural watercourses into sustainable aquatic harvest farms.³

2. Selective Breeding Pools and Decapod Conservation Cycles

In seasonal wetland complexes such as the chain of lakes along the Swan Coastal Plain (including Herdsman Lake / Ngurgenboro and Lake Monger / Galup), custodians constructed tiered holding ponds.⁴ As floodwaters receded during late spring (Kambarang) and early summer (Birak), channels connecting these ponds were selectively dammed with woven tea-tree (Melaleuca) wattles and clay bundles.⁵ Mature spawning individuals and egg-bearing females (termed berried marron) were systematically transferred upstream into deep perennial spring pools sheltered by overhanging paperbark roots.⁶ This custodial protocol ensured that reproductive stocks remained protected from dehydration and bird predation throughout the peak aridity of Bunuru.⁷

3. Technological Typology of Freshwater Fish Enclosures

Archaeological evidence from river basins across the Southwest demonstrates diverse technological adaptations tailored to specific fluvial geomorphologies.⁸ In shallow, high-velocity streams, linear stone alignment dykes forced ascending schools into narrow chutes where cylindrical reed basket traps (mungah) were anchored.⁹ In slow-moving alluvial swamps, hollowed log chambers were placed underwater to mimic submerged snag habitats, providing decoy nesting sites for freshwater cobbler that were then harvested with barbed multi-pronged spears (gidjee).¹⁰

4. Water Jurisprudence and Inter-Catchment Governance

Freshwater fisheries were governed by rigorous customary legal regimes that prohibited water poisoning or unapproved downstream flow obstruction.¹¹ Upstream clan estates were legally obligated to maintain continuous minimum environmental flows to ensure downstream estates had adequate drinking water and functional fisheries.¹² Violations of these riparian obligations triggered formal diplomatic councils (Boonaroo assemblies), underscoring the sovereign legal architecture underpinning Bibbullmun water management.¹³