Chilled storage of unfertilized and fertilized rainbow trout (Oncorhynchus mykiss) eggs in sealed polyethylene bags at different temperatures

Three experiments were conducted to study the effect of chilling temperature on unfertilized and fertilized rainbow trout eggs sealed in polyethylene (PE) bags. Experiment 1 showed that after 18 days of storage at 2 degrees C fertilization capacity of eggs was undiminished. At 7 degrees C, unimpaired fertilization capacity was maintained for 12 days and at 10 degrees C for 6 days. This leads to the conclusion that for storage up to approximately 1 week an ordinary household refrigerator will suffice; for more extended storage periods lower temperatures are advised. If PE bags filled with unfertilized eggs were submerged in water during chilling, similar results were obtained, though at a slightly lower level. The second experiment showed that fluctuations in chilling temperature between 2 degrees C and 10 degrees C were tolerated by unfertilized eggs as long as sufficient adaptation time was granted. One or two temperature changes within a 12 day period had no impact on fertilization capacity, whereas repeated changes at 2 day intervals caused a reduction in fertilization capacity. The attempt to apply the method of chilled storage of unfertilized rainbow trout eggs in PE bags to fertilized eggs (Experiment 3) indicated that early eyed eggs (14 days incubation at 10 degrees C) may be stored at 2 degrees C for 10 days without loss in hatching rate. Reasonable hatching rates may be achieved at 7 degrees C for about one week and at 10 degrees C for about 4 days. Storage of fertilized eggs of a more advanced stage of development (21 days incubation at 10 degrees C) calls for low temperature (2 degrees C) and storage periods of no > 4 days.