Histamine or scombroid fish poisoning is among the top three seafood-related public health problems reported in the United States. Epidemiological data from Hawaii between September 1989 through September 1999 indicate that mahimahi and tuna were the leading fish species implicated in illnesses due to histamine poisoning at 54 percent and 25 percent respectively. Imported "seafood" was responsible for 48 percent and imported mahimahi was responsible for 45 percent of the total number of illnesses. A practical Hazard Analysis Critical Control Point (HACCP)-based approach for controlling histamine accumulation in susceptible pelagic fish species caught by Hawaii's longline, handline, and trolling fleets was developed and explored in this project. The FDA HACCP seafood inspection program guidelines for controlling histamine accumulation recommend that fish be chilled to below 50º F within 6 hours and to below 40º F within 24 hours after death. Vessel Standard Operating Procedures (VSOP) for on-board fish handling were evaluated against these established guidelines. Fish temperature profiles were recorded at sea and compared with histamine analyses. Results suggest that Hawaii fishing fleets are capable of meeting the FDA fish handling guidelines for fish brought to the vessel alive. The actual chilling rates for fish that died on the line could not be determined. However, once boarded, fish were chilled to below 40º F within 24 hours. The histamine concentration of all fish (dead and alive) with known on-board temperature profiles was well below the FDA defect action limit of 5 mg/100g (mean = 0.26 mg/100g, range = 0.02 – 0.88mg/100g, SD 0.2 mg/100g). The efficacy of fish quality grading and sensory evaluation at the time of delivery to the first receiver was evaluated as a practical screening method for eliminating fish with high histamine risk from the market. A market sample of 583 fish from 42 commercial longline trips, 45 trolling trips, and 32 handline trips was collected, graded for quality, evaluated organoleptically, and analyzed for histamine concentration. Fish quality grading and sensory evaluation (for odors of decomposition) were effective in culling out all fish (14 out of 583 fish sampled) with high histamine concentrations. The fish rejected for odors of decomposition included bigeye, yellowfin, and albacore tuna; striped marlin; blue marlin; and mahimahi. Within the sample set of odor rejects, only bigeye tuna, yellowfin tuna, albacore tuna, and mahimahi were found with histamine levels exceeding the defect action limit. It was estimated that the actual prevalence of high-histamine fish in Hawaii's fresh fish landings is less than 0.00117 percent. A practical HACCP-based approach utilizing VSOP for controlling histamine on fishing vessels and sensory evaluation for screening for fish with high histamine risk in the Hawaii fresh tuna industry is presented in the final report.