EXPERIMENTAL-ANALYSIS OF TROUT EFFECTS ON SURVIVAL, GROWTH, AND HABITAT USE OF 2 SPECIES OF AMBYSTOMATID SALAMANDERS

Introduced fish have been implicated as reducing abundance or eliminat ing ambystomatid salamanders from montane lakes in western North Ameri ca. We tested the null hypotheses that survivorship, growth, and refug e use of larvae reared for 30 d did not differ between artificial pond s with trout and without trout Larval survivorship for both A. macroda ctylum and A. gracile was significantly lower in ponds with trout than in fishless ponds. Both species had significantly lower snout-vent le ngths in ponds with trout than in fishless ponds at the conclusion of the experiments. Only A. gracile had significantly lower body weight i n ponds with trout than in ponds without trout For both species, subst rate locations of larvae were significantly influenced by trout at the conclusion of the experiments. Larvae of both species were found in a narrower range of substrates in ponds with fish than in control ponds . Our findings support inferences from field studies that the presence of trout have negative impacts on larval A. macrodactylum and A. grac ile.