Efficiency of Gastric Lavage on Age‐0 Brook Trout and the Influence on Growth and Survival

Accurate knowledge of food webs is important in understanding aquatic ecology. One common way to determine the food web structure of an aquatic ecosystem is to perform stomach content analysis. Gastric lavage has developed into the preferred method for collecting dietary data from live fish. The objective of this study was to determine the efficiency of gastric lavage for age‐0 brook trout Salvelinus fontinalis. Also, to assess the effects on short‐ and long‐term growth and survival, age‐0 brook trout were monitored for 2 months following the gastric lavage procedure. Gastric lavage was extremely efficient (>97% of dry weight; >98% by number) at removing Ephemeroptera, Plecoptera, and Trichoptera larvae fed live to age‐0 brook trout larger than 50 mm total length (TL). Neither growth nor survival was significantly influenced by gastric lavage. Long‐term survival was excellent (94%) and did not differ from that of control fish. Gastric lavage is thus an efficient, safe method for stomach content analysis of age‐0 brook trout larger than 50 mm TL. Received September 29, 2010; accepted March 16, 2011