Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 31, 2008
Publication Date: August 1, 2009
Citation: Davis Jr, K.B., McEntire, M.E. 2009. Comparison of the cortisol and glucose stress response to acute confinement among white bass, Monrone chrysops, striped bass, Monrone saxatilis and sunshine bass, Monrone chrysops x Morone saxatilis. Journal of the World Aquaculture Society. 40(4):567-572. Interpretive Summary: Sunshine bass are a hybrid preferred by the aquaculture industry. They are produced by crossing a female white bass with a male striped bass. Striped bass grow faster than sunshine or white bass but are more sensitive to stress than the other types of fish. Plasma glucose and cortisol are useful stress indicators in fish. The glucose and cortisol responses to a low-water stress of sunshine bass are more similar to those of the white bass than those of a striped bass. These differences help explain the stress tolerance advantage in sunshine bass over striped bass. Insulin-like Growth Factor-I (IGF-I) is an important growth regulator in fish. IGF-I concentrations in the three types of fish were not different. IGF-I concentrations cannot explain the differences in growth of these fish.
Technical Abstract: Hybrid striped bass are considered more desirable than either of the parental species for aquaculture due to their fast growth and the ability to withstand handling and other stresses associated with culture conditions. Sunshine bass are the hybrid produced by crossing female white bass with male striped bass. The relative genetic contributions of the parental species in the hybrid are unknown. This study compared the plasma cortisol and glucose stress response and the resting concentration of insulin-like growth factor (IGF-I) among the parental species and sunshine bass. Blood samples were taken before and after a 15 min acute low-water stress, and 1, 2, 4, 6 and 24 hours after removing the stressor by replacing the standpipe. Low water confinement resulted in significant increases of cortisol and glucose in all three types of fish. Striped bass demonstrated the highest cortisol response and remained high during two hours of recovery. Cortisol levels in sunshine bass were higher than white bass but much lower than striped bass after 15 minutes, but both white bass and sunshine bass showed marked recovery after one hour, although recovery to pre-stress levels did not occur until four hours of recovery. An increase in plasma glucose following the stressor occurred in all three groups of fish. The glucose response was much slower than the cortisol response. A significant increase in glucose was not apparent until two hours after the beginning of the low-water stressor in sunshine bass and not until four hours in white bass. Striped bass plasma glucose levels were elevated after 15 minutes and remained high for at least six hours. Plasma IGF-I concentrations in resting fish were not different among the three types of fish. The stress responses were quantitatively higher and lasted longer in striped bass than white bass, with the sunshine bass stress responses being intermediate.