Effects of flooding dates on population dynamics in South Carolina crayfish ponds.

摘要

Production and population dynamics of Procambarus clarkii and Procambarus acutus acutus were studied in nine 0.1-ha earthen ponds at the Clemson University Aquaculture Research Facility (Clemson, South Carolina, USA) flooded in mid-September, mid-October, and mid-November 1997. Mean forage biomass estimates at flooding were similar among treatments. Mean total length (TL) of the young-of-the-year (YOY) crayfish sampled in November by dip nets from September-flooded ponds (36.7 mm TL) was significantly larger (P<0.05) than the YOY from October- (28.5 mm TL) and November- (21.8 mm TL) flooded ponds. The 1-2 month growth advantage of the YOY in the September-flooded ponds did not persist past November. The dip-netted YOY P. clarkii were significantlylarger than the netted YOY P. a. acutus from flooding to February; thereafter, P. a. acutus were similar in size or larger than YOY P. clarkii. At harvest, YOY from the September-flooded ponds (77.8 mm TL) were significantly larger than the YOY crayfishharvested from October- (72.9 mm TL) and November- (73.8 mm TL) flooded ponds. The overall mean TL for both species and cohorts of the crayfish harvested from the September-flooded ponds (79.2 mm TL) was significantly larger than crayfish from the October- (75.5 mm TL) and November- (73.9 mm TL) flooded ponds. The average size of harvested crayfish varied little during the harvest season. Production over a 40-day harvest season averaged 197.3 kg/ha and was similar among treatments. The proportion of YOY P. clarkii in dip-net samples from the September-flooded ponds was nearly double that observed in ponds flooded later. The harvest from September-flooded ponds contained significantly higher percentages of P. clarkii than the October- and November-flooded ponds.