Natural Resource Economics Commons^™

Using The Judas Technique To Locate And Remove Wintertime Aggregations Of Invasive Common Carp, P. G. Bajer, Christopher J. Chizinski, P. W. Sorensen

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Radio- and acoustic telemetry in three Midwestern lakes demonstrated that common carp, Cyprinus carpio L., aggregate as water temperatures descend below 10C. Particularly dense aggregations formed at temperatures <5 >C, and once located, these aggregations could be removed with an efficiency of up to 94% using seine nets. Carp aggregated just below the surface of the ice (approximately 1.5 m) and rarely descended to warmer waters, which extended down to 10 m. Although aggregations consistently formed close to shore, their locations could not be explained by temperature or dissolved oxygen. The aggregations also moved frequently, making radio-tagged fish invaluable to locate …

Mixed-Source Reintroductions Lead To Outbreeding Depression In Second-Generation Descendents Of A Native North American Fish, David D. Huff, Loren M. Miller, Christopher J. Chizinski, Bruce Vondracek

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Reintroductions are commonly employed to preserve intraspecific biodiversity in fragmented landscapes. However, reintroduced populations are frequently smaller and more geographically isolated than native populations. Mixing genetically, divergent sources are often proposed to attenuate potentially low genetic diversity in reintroduced populations that may result from small effective population sizes. However, a possible negative tradeoff for mixing sources is outbreeding depression in hybrid offspring. We examined the consequences of mixed-source reintroductions on several fitness surrogates at nine slimy sculpin (Cottus cognatus) reintroduction sites in south-east Minnesota. We inferred the relative fitness of each crosstype in the reintroduced populations by comparing …

Implications Of Community Concordance For Assessing Stream Integrity At Three Nested Spatial Scales In Minnesota, U.S.A., Christine L. Dolph, David D. Huff, Christopher J. Chizinski, Bruce Vondracek

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

1. Fish and invertebrate assemblage data collected from 670 stream sites in Minnesota (U.S.A.) were used to calculate concordance across three nested spatial scales (statewide, ecoregion and catchment). Predictive taxa richness models, calibrated using the same data, were used to evaluate whether concordant communities exhibited similar trends in human-induced taxa loss across all three scales. Finally, we evaluated the strength of the relationship between selected environmental variables and the composition of both assemblages at all three spatial scales.

2. Significant concordance between fish and invertebrate communities occurred at the statewide scale as well as in six of seven ecoregions and …

Breeding Bird Response To Partially Harvested Riparian Management Zones, Christopher J. Chizinski, Anna Peterson, Joann Hanowski, Charles R. Blinn, Bruce Vondracek, Gerald J. Niemi

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

We compared avian communities among three timber harvesting treatments in 45-m wide even-age riparian management zones (RMZs) placed between upland clearcuts and along one side of first- or second-order streams in northern Minnesota, USA. The RMZs had three treatments: (1) unharvested, (2) intermediate residual basal area (RBA) (targeted goal 11.5m²/ha, realized 16.0m2/ha), and (3) low RBA (targeted goal 5.7m²/ha, realized 8.7m²/ha). Surveys were conducted one year pre-harvest and three consecutive years post-harvest. There was no change in species richness, diversity, or total abundance associated with harvest but there were shifts in the types of …