PRELIMINARY INVESTIGATION OF THE EFFECTS OF TEMPERATURE, BACTERIAL INOCULATION, AND EDTA ON SPERM QUALITY IN CAPTIVE Penaeus setiferus

A 60‐day preliminary study was conducted to determine whether excessive temperature, bacterial infection, or heavy metals contamination contributed to spermatophore and sperm deterioration in laboratory‐held Penaeus setiferus males. Three treatments were tested in which: 1) culture water temperature was held at 25–26°C; 2) males were inoculated with a killed Vibrio sp. bacterin ; and 3) EDTA (ethylenediaminetetraacetic acid) was added to culture water at 25 ppm. These were compared with a control treatment at mean ambient temperature of 29.1°C. A combination of males from the primary offshore breeding population (mean weight 43.9 g ± 1.78 S.E.M.) and young‐of‐the‐year males (mean weight 24.5 g ± 0.83) were used. Mean baseline values (± S.E.M.) established at initiation were, per male: sperm count, 38.7 × 10 6 ± 10.165 × 10 6 ; percent abnormal sperm, 5.0% ± 1.13; and spermatophore weight, 0.103 g ± 0.0215. At the midpoint 30‐day samples, mean sperm counts were significantly lower in the ambient and EDTA treatments. The chilled and inoculated treatments showed no decline in sperm counts during the first 30‐day period, but the percentage of abnormalities had increased from 5.0% ± 1.13 in the baseline to 16.3% ± 9.94 and 57.0% ± 9.64, respectively. At termination (60 days), only the chilled treatment contained any males bearing sperm (33% of males sampled from the treatment), but sperm abnormalities ranged from 53–72%. Results indicate that parameters tested did not prevent decline in male reproductive condition over time.