Physiological responses of <i>Clarias gariepinus</i> (Burchell 1822) broodstock to confinement stress.

Abstract

Stress increases the incidence of diseases and mortality thus affecting the economics of aquaculture. This study therefore, investigates the physiological responses of Clarias gariepinus broodstock to confinement stress by examining secondary stress response levels (haematological and biochemical parameters) and gamete qualities at different confinement periods of 0, 24, 48 and 72 hours. Highest mass activity of spermatozoa was recorded at 0 hr of confinement while it decreases from active (24 and 48 hrs) to passive (72 hrs of confinement). The fish confined for 0 hr had best hatching and survival rates of 95.7 and 70% respectively. While fish confined for 72 hrs recorded the lowest hatchability and survival rates of 68.60 and 45.50%. The White Blood Cell value increases from 10366.7C/mm3 at 0 hr to 10866.7C/mm3 after 24 hours of confinement, this later reduced to 10400.0C/mm3 at both 48 and 72 hrs. The mean Packed Cell Volume level decreases from 38.0 ± 1.08g/l at 0 hour of confinement to 37.5 ± 0.95g/l after 48 hrs confinement, this later increased significantly (P< 0.05) to 42.0 ± 0.74g/1 at 72 hrs. The plasma glucose level increased significantly (P < 0.05) from 34.33 ± 3.16 mg/dl at 0 hrs to 46.00 ± 1.80mg/dl at 72 hrs. This study shows that C. gariepinus broodstock should not be confined for more than 24 hrs before breeding in other to reduce stress and improve reproductive performance.

Keywords: Blood Chemistry, Clarias gariepinus broodstock, Confinement stress.