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Comparison of Snorkel and Mark–Recapture Estimates for Trout Populations in Large Streams
Author(s) -
Zubik Raymond J.,
Fraley John J.
Publication year - 1988
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(1988)008<0058:cosamr>2.3.co;2
Subject(s) - flathead , trout , fishery , fish measurement , salmo , streams , fishing , environmental science , fish <actinopterygii> , biology , computer network , computer science
The abundance of westslope cutthroat trout Salmo clarki lewisi was estimated in three sections of the South Fork of the Flathead River. We made two different Petersen mark–recapture estimates (angling only and angling with snorkeling) and compared them to a snorkel‐expansion estimate. Anglers caught and snorkelers classified similar size‐groups ofcutthroat trout. The snorkel‐expansion estimate was similar to the two Petersen estimates. In one section, we estimated total abundance at 452, 527, and 546 cutthroat trout/km by the hook‐and‐line Petersen, snorkel‐Petersen, and snorkel‐expansion methods, respectively. In a second section, we estimated 215 and 221 cutthroat trout/km by the snorkel‐Petersen and snorkel‐expansion methods, respectively. In a third section, we estimated 183 and 201 cutthroat trout/km by the snorkel‐Petersen and snorkel‐expansion methods, respectively. We concluded that, in large clear streams with little cover, the snorkel‐expansion method provides a quick, reliable density estimate at relatively low cost.