Common carp Cyprinus carpio is a widespread invasive species that can become highly abundant and have deleterious ecosystem effects. Thus, aquatic resource managers are interested in controlling common carp populations, but control is difficult, in part, because of the inherent uncertainty as to how populations respond to exploitation. To better understand this response, we evaluated the population dynamics (recruitment, growth, and mortality) of common carp in three natural lakes in eastern South Dakota. Common carp exhibited similar population dynamics across these three systems, which were characterized by consistent recruitment (ages 3-15 being present), fast growth (K = 0.37-0.59), and low mortality (A = 1-7%). We then modeled the effects of commercial exploitation on size structure, abundance, and egg production to determine its utility as a management tool to control populations. All three populations responded similarly to exploitation simulations in which a 575-mm length restriction represented commercial gear selectivity. Simulated common carp size structure declined modestly (9-37%) in all simulations. The abundance of common carp declined dramatically (28-56% of starting levels) at low levels of exploitation (0-20%), but exploitation greater than 40% had little additive effect, the final populations only being reduced 49-79% despite high exploitation (>90%). At a moderate level of exploitation (40%), maximum lifetime egg production was reduced to 77-89% of starting levels, indicating the potential for recruitment overfishing. Exploitation further reduced common carp size structure, abundance, and egg production when simulations were not size selective. Our results provide insights into the ways in which common carp populations may respond to exploitation. Although commercial exploitation may be able to partially control populations, an integrated removal approach that removes all sizes of common carp has a greater chance of controlling population abundance and reducing the perturbations induced by this invasive species.

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The USACE technical leads were Mr. Brad Eppard and Mr. Fred Higginbotham. The study was designed to evaluate the passage and survival of yearling and subyearling Chinook salmon and juvenile steelhead at McNary Dam as stipulated by the 2008 Biological Opinion and Fish Accords and to assess performance measures including routespecific fish passage proportions, travel times, and survival based upon a virtual/paired-release model. This study supports the USACE's continual effort to improve conditions for juvenile anadromous fish passing through Columbia River dams.

Common Carp Cyprinus carpio form dense populations that often negatively impact water quality and clarity, native fish communities, and aquatic plant growth in aquatic ecosystems outside their native range, including the U.S. Midwest. In an attempt to guide future management and control activities, we used acoustic telemetry to quantify monthly spatial distributions and movement patterns for adult Common Carp in Brant and Round lakes, South Dakota, during open‐water periods for 2 years. During a span of 12 months of manual tracking in the spring, summer, and fall seasons, we obtained 530 locations from 19 acoustically tagged fish. In general, fish displayed a clear tendency to aggregate in shallow depths close to shore during the spawning period in May and June and also postspawn during August. In contrast, fish dispersed offshore into deeper water during July. Mean hourly movement rates during 24‐h tracking sessions ranged from 100.3 m/h to 165.9 m/h. Although nonsignificant, the highest movement rates occurred in June and October and during the dusk period. Our results, along with similar studies in the region, indicate predictable and repeatable seasonal aggregations and distributions of Common Carp that will likely aid in the development of sampling protocols and control programs for temperate lakes. These results can be used to develop integrated control techniques that would target adult fish during periods of seasonal aggregations and dispersions, which is critical for effective population control. Received March 26, 2014; accepted August 23, 2014