9/3/24 – Improving fishing at Wahiawā PFA, O‘ahu
Water hyacinth root system
The Wahiawā Reservoir fishery is being impacted by low water levels, predation and competition by introduced predatory fish species, lack of habitat/shelter and food fish. Due to dam safety concerns the water levels in the reservoir are maintained at 60 t0 65 feet. The steep clay banks at this level are bare and not advantageous for growing grass or brush. Natural fluctuating water levels are more favorable for providing habitat, spawning areas, and exposing food sources (such as bugs, small fish, etc.) and have proven important in maintaining and sustaining productive and healthy fisheries in reservoirs.
To improve the lack of habitat/shelter and food sources, the Division deployed trial oil booms and pvc rafts containing water hyacinth anchored along bank areas. Routine thinning of the hyacinths in the enclosures contained small fishes including juvenile Jewel cichlids, Chinese catfish, crayfish and amphipods in the root system which is a good indication that the booms are working in providing habitat/shelter and food source for the larger gamefish.
Low water and exposed bare banks next to boat launch ramp.
PVC rafts with water hyacinth.
Left: filling boom with water hyacinth; right: oil boom containment for water hyacinth.
Left: juvenile Chinese catfish; right: juvenile jewel cichlid.