Engineering research for improvement of freshwater prawn harvest yield in Hawaii

Engineering research for improving freshwater prawn harvest yield in Hawaii has focused on the development of management strategies and techniques. First, a mark and capture method was developed to estimate harvest efficiency. The average harvest efficiency in early commercial ponds was found to be only 24·08%; this led to the belief that low and inconsistent harvest yields were due to low and inconsistent harvest efficiency. An improved harvesting system was then developed which produced an average harvest efficiency of 63·5%. A study was also done to compare the effects of different pond bank grass management practices on harvest yields. It was found that reduction of bank grass without any other changes in management can increase the yield to 2179 kg ha−1 year−1, which is almost 1·5 times the 1984 state average yield. An experiment to study the effects of higher harvest efficiency on yield is in progress.