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Tuesday, January 30 • 1:40pm - 2:00pm
SYMPOSIA-07: Simultaneously Assessing Channel Catfish and Flathead Catfish Populations with Unbaited Hoop Nets in the Minnesota River

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AUTHORS. Anthony R. Sindt, Minnesota Department of Natural Resources

ABSTRACT. Fisheries managers desire efficient sampling methods with sufficient precision for monitoring catfish populations.  We conducted single unbaited hoop net surveys in the Minnesota River to evaluate efficacy of simultaneously assessing stock size (= 280 mm) Channel Catfish Ictalurus punctatus and quality size (= 510 mm) Flathead Catfish Pylodictis olivaris populations.  We compared catch rates and length distributions among months, and used resampling procedures to estimate the number of hoop net samples needed to achieve desirable precision (i.e., RSE = 25 and RSE = 15) of catch rate estimates and adequate statistical power (= 0.80 with a = 0.10) to detect simulated reductions in mean catch rates with two-tailed t-tests.  We observed mean ± SE catch rates of 2.1 ± 0.3 Channel Catfish/net-night and 0.8 ± 0.1 Flathead Catfish/net-night.  Resampling procedures demonstrated a minimum of 68 hoop net samples during August are needed to achieve desirable precision (RSE = 25) and adequate statistical power to detect 50% reductions in mean catch rates of both species.  Unbaited hoop nets are effective for simultaneously assessing Channel Catfish and Flathead Catfish populations in the Minnesota River and conducting surveys during August provides the best balance between catch rate and precision while minimizing perceived environmental and behavior biases.  We expect the same could be true for other rivers with moderate–high density Channel Catfish and Flathead Catfish populations, but the best time of year for conducting surveys likely varies regionally.  However, the amount of sampling effort needed to detect small population changes (

Tuesday January 30, 2018 1:40pm - 2:00pm CST
102A