Influence of sampling on the interpretation of haematological measurements of rainbow trout, Salmo gairdneri
Haematological parameters of rainbow trout (Salmo gairdneri) were examined to determine if the sampling influenced the measurements. The results indicated that haematocrit values of fish anesthetized with tricaine methanesulfonate (TMS or MS 222) sampled after 5–20 min were significantly higher than of fish sampled within 1 min of capture and anesthesia. No differences were observed among haemoglobin content, erythrocyte, and leucocyte counts or their differential cell ratios over the 20-min period. Haemoglobin content and erythrocyte counts increased significantly with size among the three groups examined. It is suggested that differential blood cell ratios could be used as a reliable haematological index because the ratios appear to be independent of the effects of sampling over a short time period.