Title: Comparison of the Cortisol and Glucose Stress Response to Acute Confinement and Resting Insulin-Like Growth Factor-I Concentrations among White Bass, Striped Bass and Sunshine Bass Authors
Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 4, 2005
Publication Date: February 13, 2006
Citation: Davis Jr., K.B., McEntire, M.E. 2006. Comparison of the cortisol and glucose stress response to acute confinement and resting insulin-like growth factor-I concentrations among white bass, striped bass and sunshine bass [abstract]. Aquaculture America 2006 Book of Abstracts. p. 79. Technical Abstract: Sunshine bass are hybrids produced by crossing female white bass with male striped bass. The hybrid is thought to be more desirable for aquaculture due to fast growth and the ability to withstand handling and other stresses associated with culture conditions. The relative contribution of the parental species in the hybrid are relatively unknown. This study compares the plasma cortisol and glucose stress response and the resting concentrations of insulin-like growth factor-I (IGF-I) among the parental species and sunshine bass. Fish respond to a variety of stressful conditions by secreting cortisol and glucose into the blood stream. IGF-I is a growth regulating hormone produced by the liver under the stimulation of growth hormone from the pituitary and is thought to be responsible for stimulating somatic growth. A 15 minute acute low-water stress response was achieved by lowering the water volume from 60 to 5 l in about 5 min. The fish were held at the reduced water volume for 10 minutes and the original water volume restored. Blood samples were taken before water reduction, after 15 minutes of low water confinement, and 1, 2, 4, 6 and 24 hours after replacing the standpipe. Plasma cortisol and IGF-I concentrations were determined by radioimmunoassay and plasma glucose was determined by the glucose oxidase procedure. Low-water confinement resulted in significant increases of plasma cortisol after 15 minutes in all three species. Striped bass demonstrated the highest cortisol concentrations and remained high for 2 hours of recovery. Cortisol levels in sunshine bass were higher than white bass but lower than striped bass after 15 minutes but both fish showed marked recovery after 1 hour although recovery to pre-stress levels did not occur until 4 hours of recovery. A secondary increase occurred in both white bass and sunshine bass at 6 hours during recovery. An increase in plasma glucose following the stressor occurred in all three species. The response was much slower than the cortisol response. Increased plasma glucose was not apparent until 2 hours after the end of the stressor in sunshine bass and not until 4 hours in white bass. Striped bass plasma glucose levels were elevated after 15 minutes and remained high for 6 hours. Plasma IGF-I concentrations were only measured in the pre-stressed animals and were not significantly different among the three species. Striped bass were most affected by the stressor and white bass were affected the least. Sunshine bass responses were intermediate.