<p> Bighead Carp <i>Hypophthalmichthys nobilis</i> and Silver Carp <i> H. molitrix</i> (collectively referred to as bigheaded carp) were introduced to the United States in the 1970s and escaped into the Mississippi River from aquaculture ponds. Since their escape, bigheaded carp have become established in the Mississippi River Basin, including the Ohio River and its tributaries. More recently, bigheaded carp have invaded the Tennessee and Cumberland rivers. Little research has been conducted on bigheaded carp in Tennessee waters, with preliminary studies investigating the distribution and characteristics of established bigheaded carp populations, including growth rates and recruitment. My study represents the first systematic sampling of bigheaded carp in the Tennessee and Cumberland rivers, both tributaries to the Ohio River, and in large reservoirs in the southeast U. S. Standardized, multi-gear sampling methods were used to sample bigheaded carp in Kentucky Lake and Pickwick Lake on the Tennessee River and Lake Barkley and Cheatham Lake on the Cumberland River in 2017 and 2018. Overnight gill nets were the most effective gear, capturing an average of 17 Silver Carp per gill net gang. Short-set gill nets captured an average of one Silver Carp per gill net gang, and electrofishing captured an average of one Silver Carp per 10-minute electrofishing transect. Maximum total length (TL) was 1,390 mm for Bighead Carp and 1,111 mm for Silver Carp, and the maximum age for both species was 11 years. Average age and condition of Silver Carp was higher in upstream impoundments than downstream, and thus suggested an early invasion period from Ohio River movements. Gonadosomatic index (GSI; egg mass weight to body weight ratio) was also higher in upstream impoundments than downstream impoundments. Higher GSI values were observed in the spring and summer, when bigheaded carp may begin to spawn in response to high flows. Length-at-age estimates for the four reservoirs suggested bigheaded carp growth rates in the Tennessee and Cumberland rivers are similar to other populations in the US, indicating populations may be experiencing density effects in southeastern impoundments. No young of year (YOY) bigheaded carp were captured during the study, but weak and missing year classes due to erratic recruitment patterns are common in bigheaded carp, and monitoring for YOY fish should continue. Mean catch-per-unit-effort (CPUE) was not significantly different among reservoirs for the three gear types, and no significant seasonal variation in mean CPUE was observed for overnight gill nets. A lack of differences in CPUE across sampling seasons suggested population densities could be assessed as agencies could fit into their schedules. Overall, the results represent the first large-scale standardized sampling effort for bigheaded carp across four southeastern states and provide integral population information for natural resource managers. Future monitoring efforts should continue to track characteristics of bigheaded carp populations in the Tennessee and Cumberland rivers and determine effective control and management strategies for populations in large impoundments. </p><p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10979492 |
| Date | 30 January 2019 |
| Creators | Fernholz, Savannah |
| Publisher | Tennessee Technological University |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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