Effect of temperature on sperm quality of captive Litopenaeus vannamei broodstock

Effect of temperature on reproductive quality of captive male Litopenaeus v annamei broodstock was investigated by measuring sperm count and percentage of abnormal sperm per compound spermatophore. Variability in these respons es among and within experimental units also was evaluated. Male shrimp with an initial average weight of 48.0 g were maintained in 3.7-m diameter circ ular tanks with recirculating seawater, and exposed to constant temperature s of 26 degreesC, 29 degreesC, and 32 degreesC for 42 days. Significantly h igher mean sperm count (18.6 million cells) and lower percentage of sperm a bnormalities (36.7%) were observed in shrimp held at 26 degreesC, as compar ed to broodstock at 29 degreesC (mean sperm count = 0.1 million cells; perc entage of sperm abnormalities = 99.7%) or 32 degreesC (no sperm cells)(P < 0.05). Results indicate that adequate sperm count and percentage of abnorma l sperm of L. vannamei broodstock can be maintained at water temperature of 26 degreesC, but not at 29 degreesC or 32 degreesC, at least within the ti me span of 42 days. The importance of treatment replication and sampling su fficient numbers of shrimp from culture tanks in experiments concerning mal e reproductive quality is discussed. (C) 2001 Elsevier Science B.V. All rig hts reserved.