Common Carp Population Size and Characteristics in Lake Carl Etling, Oklahoma
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Common Carp (Cyprinus carpio) is a highly invasive species and tolerates a diversity of habitats with a broad range of water-quality characteristics. Following extended drought conditions from 2005 - 2012, a noticeable increase in Common Carp densities was observed at Lake Carl Etling. Higher Common Carp numbers suggested other management techniques would be needed to control the population, which required knowledge of Common Carp population abundance. Therefore, our objective was to estimate the population size using a Schnabel estimator, body condition, and size structure of the carp population. We sampled the entire perimeter of the shoreline once monthly using boat electrofishing from May through November 2017. During the first sampling event in May, all Common Carp captured were measured (total length [TL], mm), weighed (g), given a hole punch mark through the left operculum, and released. In subsequent samples (June-November), each captured fish was examined for a hole punch mark on the left operculum, and if present was recorded as a recapture and released. However, if no mark was observed, the fish was measured, weighed, marked, and released. The mark recapture population estimate was constrained to Common Carp >200 mm because small fish (< 200 mm) were not fully recruited to the electrofishing gear. During the six month mark-recapture period, 2,848 Common Carp ranging 111 to 620 mm TL were collected. We marked and released 2,752 (≥ 200 mm TL) of the 2,848 fish captured. We recaptured 207 marked fish, resulting in a population estimate of 13,783 Common Carp (95% CI = 11,262-16,648). Common Carp density was estimated at 214 fish/ha -1 (95% CI = 181-267 fish/ha -1 ) and biomass was 148 kg/ha -1 (95% CI = 125-184 kg/ha -1 ). Most (93%) Common Carp in Lake Carl Etling were < quality size, but a small proportion exceeded preferred size. Condition of Common Carp in this population was below average (mean Wr = 90). Our results suggest the density of Common Carp in Lake Carl Etling is high and may be regulating size structure and condition of these fish. Further, based on our results fisheries managers can remove enough Common Carp from this system to improve water quality conditions and sport fish populations.