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Evaluation of Marking Techniques to Estimate Population Size and First‐Year Survival of Colorado Squawfish
Author(s) -
Haines G. Bruce,
Modde Timothy
Publication year - 1996
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(1996)016<0905:eomtte>2.3.co;2
Subject(s) - population , fish <actinopterygii> , zoology , biology , predation , statistics , environmental science , fishery , toxicology , ecology , mathematics , demography , sociology
Three marking methods‐tattoo ink injected with a dental inoculator, an elastic polymer injected by syringe, and fin clipping—were tested to determine a suitable technique for estimating population size, survival, and movement of age‐0 Colorado squawfish Ptychocheilus lucius . Laboratory tests indicated that all three marks were retained at sufficient rates (>97%) to make population estimates over a 21‐d period. However, fish marked with tattoo ink had higher mortality (10%) than fish marked with elastic polymer (< 1%) or with a fin clip (0%). Fish marked with the elastic polymer had higher retention (85%) than those marked with fin clips (34%) or tattoo ink (26%) after 142 d. No differences in vulnerability to predation were observed among fish with the three marks or between marked and unmarked fish. A field test of the elastic polymer showed that it was easy to use, caused low mortality (5% for fish held overnight in live‐cages), and produced marks that were readily visible, Mark–recapture methods were used to estimate population size of Colorado squawfish (5,595 in the autumn and 2,523 the following spring) and winter survival (45%). Survival estimates from mark–recapture data were more accurate and precise than those from catch‐per‐unit‐effort data, at least for short‐term studies in river reaches less than 50 km long. Simulations showed that doubling the size of the study section and increasing the probability of capture by 33% would reduce possible bias from 14.5% to 1.4% and the coefficient of variation (SE/mean) from 0.25 to 0.06.