Seasonal movements and spatial distributions of common carp in an interconnected glacial lake system in eastern South Dakota.

摘要

The common carp Cyprinus carpio is a ubiquitous invasive species naturalized to aquatic systems throughout North America. Management strategies for overabundant common carp populations are typically aimed at population reduction with the goal of improving water quality and habitat to enhance native fish communities. In order to choose efficient and cost effective control techniques, an understanding of common carp seasonal movement patterns and spatial distributions is essential. Therefore, the objectives of my research were to: (1) evaluate seasonal and diel movement patterns of common carp in a shallow (5 m), interconnected glacial lake system in eastern South Dakota, and (2) examine seasonal spatial distributions.;To address the objectives, both manual and fixed-position ultrasonic telemetry were used year-round on Brant and Round lakes, a 500-ha interconnected glacial lake system in eastern South Dakota. Adult common carp mean hourly movement rates per 24-h tracking session ranged from 100.3 m/h (SE=25.1) in August to 165.9 m/h (SE=28.1) in October, but movement rates did not differ (P>0.05) in June, July, August, and October indicating that fish moved consistently at the same rate during this period. Movement rates did not differ among diel periods across months or diel periods within months. Activity under the ice was highest in March of both winters compared to previous months and no difference was detected between large and small fish activity. Spatial segregation between large adult common carp and small carp occurred in June 2009 during spawning when adults were located closer to shore in shallower depths. In addition, spatial segregation was detected during winter months as small fish were detected in the eastern part of Brant Lake earlier and for a prolonged period of time, as compared to large fish.;Mean monthly depth at location and distance to shore for adult common carp followed similar yearly trends. Adult common carp were found at shallow depths (1.8 m) and close to shore (100 m) in May and June of both years during peak spawning activity. Following spawning, a similar pattern was observed both years where common carp moved offshore (>130 m) to deeper water in July (>2.2 m) and then back inshore (110 m) to shallower depths in August (1.9 m). Common carp were found offshore (>170 m) in deeper water (>2.4 m) September through November in 2008. Male and female common carp were located at similar depths and distances from shore in all months except June 2008 when female carp were found at significantly shallower depths and closer to shore.;The distribution of adult common carp locations during open water periods was non-random over the two-year study period, based on a randomization analysis. Monthly distributions of adult common carp locations were non-random in May, June, August, and October of 2008 and June of 2009. Random distributions occurred in July, September, November of 2008 and April, May, July, and August of 2009. An assessment of the amount of clustering of fish locations using a nearest neighbor index (NNI) and Ripley's K-function analysis were performed to detect aggregations. The NNI analysis indicated that the locations of carp in May, June, July, and August of 2008 and June of 2009 were more clustered than a random distribution and the lowest amount of clustering occurred in July of 2008. In contrast, common carp were more randomly distributed throughout the basin during July of 2009. The Ripley's K-function analysis indicated common carp locations in May, June, and August of 2008 were more clustered at all distances then carp locations in July of 2008. Carp were the most clustered at a distance of 150 m in June and most dispersed at a distance of 600 m in July. Distinct under-ice distribution and activity patterns of adult carp were detected in Brant Lake over the two year study period and carp displayed a clear tendency to aggregate and restrict activity within the western portion of the lake. (Abstract shortened by UMI.)