CONDITION FACTOR AND HEPATOSOMATIC INDEX AS ESTIMATES OF ENERGY STATUS IN MALE 3-SPINED STICKLEBACK

Seasonal variation indirect and indirect measures of energy status was examined using estimates of glycogen, lipid and protein levels in a s ingle cohort of male three er-spined sticklebacks from an annual popul ation collected each month over one complete year. Condition factor, s omatic condition factor and hepatosomatic index (HSI) were calculated as indirect indices of energy status and the accuracy of these indirec t measures as predictors of energy status was investigated. Results in dicate that both condition factors were significant predictors of ener gy reserves (lipid, protein. glycogen and total energy), but that the proportion of variance accounted for was small. Both condition Factors perform better as predictors of energy content per unit body weight. The HSI was a significant, but a weak predictor of total glycogen leve ls over the whole year. On a seasonal basis the relationship between H SI and energy reserves was highly variable. These indices are therefor e poor predictors of energy reserves in male three-spined sticklebacks . (C) 1995 The Fisheries Society or Ihd British Isles