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A Method to Measure Emergence Success of Westslope Cutthroat Trout Fry from Varying Substrate Compositions in a Natural Stream Channel
Author(s) -
Weaver Thomas M.,
Fraley John J.
Publication year - 1993
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1993)013<0817:amtmes>2.3.co;2
Subject(s) - trout , substrate (aquarium) , oncorhynchus , fish <actinopterygii> , streams , environmental science , fishery , ecology , biology , computer network , computer science
This study developed a field method to examine emergence success of fry of westslope cutthroat trout Oncorhynchus clarki lewisi in relation to varying levels of fine substrate materials in a natural stream environment. We attempted to simulate natural incubation conditions in a stream by constructing cells with particle sizes and egg pockets characteristic of natural westslope cutthroat trout redds. We found a significant inverse relationship ( r 2 = 0.72, P < 0.005, N = 17) between fry emergence success, as measured by fry emergence traps, and the percentage of substrate materials less than 6.35 mm in diameter. Mean fry emergence success was 76, 55, 39, 34, 26, and 4%, respectively, in cells containing 0, 10, 20, 30, 40, and 50% substrate materials less than 6.35 mm. There were no significant differences in length or weight of fry emerging from the six gravel mixtures. Using the methods and results presented in this study, as well as previous laboratory results, resource managers could develop substrate quality guidelines for westslope cutthroat trout reproduction in streams affected by land management practices.