Movement and Growth of Wild Brown Trout in the Chattahoochee River below Lake Lanier, Georgia

The Georgia Wildlife Resources Division (WRD) conducted a tagging study from April 2011 to May 2012 to study growth of wild brown trout (Salmo trutta) in the Lake Lanier Tailwater section of the Chattahoochee River. Sampling occurred monthly at four sites and fish were tagged with VI- Alpha tags on nine occasions between April 2011 and March 2012 for subsequent recapture. Follow-up samples in June and December 2012 confirmed a lack of movement between sites by any tagged brown trout that was seen in the previous samples. Growth increments between tagging and recapture events were calculated and used to estimate average length at age. More than 80% of brown trout collected measured between 17.5 and 27.5 cm TL. Brown trout appeared to initially grow rapidly, likely reaching quality size (23 cm total length [TL]) within two years. Growth rapidly slowed, however, as fish approached 30 cm. A few individuals exhibited faster growth rates and attained larger sizes, which was most likely due to transition to piscivory. Accordingly, the general strong decline observed in growth rate among larger fish is potentially a result of limited forage in a relatively unproductive river.

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