Assessment of Water Quality Characteristics in Hawaiian Fishponds As Indicators of Suitability for Aquaculture

There may be untapped potential for sustainable aquaculture in traditional Hawaiian fishponds as an alternative to wild harvest and shipment of seafood products to the state. In an effort to resolve the feasibility of growing a traditionally cultured species, striped mullet (Mugil cephalus), and its impacts on adjacent ecosystems, baseline water quality sampling and analyses were conducted at three traditional Hawaiian fishponds on the islands of Oahu and Molokai. Monitoring of water quality parameters; salinity, temperature, dissolved oxygen, pH, turbidity, chlorophyll a., nitrate, nitrite, ammonia, orthophosphate and silica, was conducted prior to and during grow-out, for a total of one year at stations within the ponds and in coastal waters adjacent to them. Three stocking densities (0.89, 1.78, and 3.56 m²) were tested in two of the fishponds in three 1-acre net pens. The smallest of the fishponds was stocked only at the intermediate density. Fish growth was monitored monthly for four months. An analysis will be presented of spatial and temporal variability of fishpond sites and the relation of variability in water quality to the dynamics of fish growth rates at the three stocking densities.