Pilot-scale production of mysid shrimp in a static water system

Studies were conducted to determine the potential for large scale culture o f the mysid shrimp Mysidopsis almyra. Reproduction was consistent, as newly hatched mysids were always present in the culture trays. At the end of 45 day preliminary trials, the populations in the culture trays had increased 323.3% and 256.6%. A larger pilot-scale system connected to a biological fi ltration tank was constructed and operated for 17 weeks. Two rectangular tr ays (125 cm x 50 cm x 8 cm deep) were placed one above the other; water vol ume in each tray was 201. The room was kept dark. Temperatures were maintai ned at 26(2) degrees C and salinities at 20(2)parts per thousand. A total o f 1,000 adult mysids were placed in the culture tray and the hatchlings wer e collected and moved into a hatchling tray. Water circulation was static e xcept for twice-daily water exchanges; newly hatched Artemia nauplii (24 h incubation) were fed to the mysids immediately after each water exchange. F eeding presented no technical problem to the pilot-scale culture of mysids in static water systems but the cost of Artemia did represent the largest e xpense. Mean (SD) mysid production throughout the 17 weeks of the trial was 133(69) hatchlings d(-1) with highest production [244(30) hatchlings d(-1) ] occurring between weeks 11 and 13. Mean survival in the hatchling tray af ter the 14 day growth periods was 41.4%. Reproduction occurred at ammonia-n itrogen and nitrite-nitrogen concentrations as high as 1.5 mg l(-1) and 0.2 50 mg l(-1) respectively, and at pH values as low as 7.6. When pH decreased to 7.38, reproduction halted abruptly and mortality increased sharply.