Search USGS⌕ Search

Geology topics

P.W. Bettoli

Publications and source records attributed to P.W. Bettoli.

9 recordsLinked to original sources
USGS2011

Movement of saugers in the lower Tennessee River determined by radio telemetry, and implications for management

Since 1979, abundances of sauger Stizostedion canadense have declined in the Tennessee River system. Reasons for this decline may include overharvest, loss of spawning habitat, and low recruitment due to extreme flows. The purpose of this study was to investigate the movements of saugers following winter concentration below Pickwick Dam, Tennessee. Thirty-seven saugers were implanted with radio transmitters directly below Pickwick Dam and were tracked between December 1992 and June 1993. Four saugers moved upstream through the locks at Pickwick Dam: the remaining fish stayed within the first 30 km of the tailwater throughout the spawning season. Three areas below Pickwick Dam were identified as possible March prespawn staging sites. After April 1, saugers in the tailwater area began a rapid downstream migration to the main basin of Kentucky Lake. Some fish moved downstream more than 200 km in less than 10 d in this semiclosed system. Movements encompassed four states (Kentucky, Tennessee, Mississippi, and Alabama) along the Tennessee River system, underscoring the need for interjurisdictional management.

Alabama, Mississippi, Tennessee↗
USGS2007

Thiamine and fatty acid content of walleye tissue from three southern U.S. reservoirs

We determined the thiamine concentration in egg, muscle, and liver tissues of walleyes Sander vitreus and the fatty acid content of walleye eggs from three southern U.S. reservoirs. In two Tennessee reservoirs (Dale Hollow and Center Hill), in which there were alewives Alosa pseudoharengus in the forage base, natural recruitment of walleyes was not occurring; by contrast in Lake James Reservoir, North Carolina, where there were no alewives, the walleye population was sustained via natural recruitment. Female walleye tissues were collected and assayed for thiamine (vitamin B1) and fatty acid content. Thiamine pyrophosphate was found to be the predominant form of thiamine in walleye eggs. In 2000, mean total egg thiamine concentrations were similar among Center Hill, Dale Hollow, and Lake James reservoirs (2.13, 3.14, and 2.77 nmol thiamine/g, respectively). Egg thiamine concentration increased as maternal muscle (r 2 = 0.73) and liver (r2 = 0.68) thiamine concentration increased. Walleye egg thiamine does not appear to be connected to poor natural reproduction in Tennessee walleyes. Threadfin shad Dorosoma petenense, which are found in all three reservoirs, had higher thiaminase activity than alewives. Six fatty acids differed among the walleye eggs for the three reservoirs. Two were physiologically important fatty acids, arachidonic acid (20:4[n-6]) and docosahexaenoic acid (22:6[n-3]), which are important eicosanoid precursors involved in the regulation of biological functions, such as immune response and reproduction. ?? Copyright by the American Fisheries Society 2007.

Journal of Aquatic Animal Health↗
USGS2007

Lack of size selectivity for paddlefish captured in hobbled gillnets

A commercial fishery for paddlefish Polyodon spathula caviar exists in Kentucky Lake, a reservoir on the lower Tennessee River. A 152-mm (bar-measure) minimum mesh size restriction on entanglement gear was enacted in 2002 and the minimum size limit was increased to 864 mm eye-fork length to reduce the possibility of recruitment overfishing. Paddlefish were sampled in 2003-2004 using experimental monofilament gillnets with panels of 89, 102, 127, 152, 178, and 203-mm meshes and the efficacy of the mesh size restriction was evaluated. Following the standards of commercial gear used in that fishery, nets were "hobbled" (i.e., 128 m ?? 3.6 m nets were tied down to 2.4 m; 91 m ?? 9.1 m nets were tied down to 7.6 m). The mean lengths of paddlefish (Ntotal = 576 fish) captured in each mesh were similar among most meshes and bycatch rates of sublegal fish did not vary with mesh size. Selectivity curves could not be modeled because the mean and modal lengths of fish captured in each mesh did not increase with mesh size. Ratios of fish girth to mesh perimeter (G:P) for individual fish were often less than 1.0 as a result of the largest meshes capturing small paddlefish. It is unclear whether lack of size selectivity for paddlefish was because the gillnets were hobbled, the unique morphology of paddlefish, or the fact that they swim with their mouths agape when filter feeding. The lack of size selectivity by hobbled gillnets fished in Kentucky Lake means that managers cannot influence the size of paddlefish captured by commercial gillnet gear by changing minimum mesh size regulations. ?? 2006 Elsevier B.V. All rights reserved.

Fisheries Research↗
USGS2006

Growth, body condition, reproduction and survival of stocked barrens topminnows, Fundulus julisia (Fundulidae)

We documented the fate of 29 cohorts of propagated Barrens topminnows Fundulus julisia stocked as juveniles and adults (ntotal = 2770 fish) into 17 springheads and small ponds in middle Tennessee in 2003 and 2004. Annual mortality rates were calculated after estimating the number of individuals of each cohort remaining 1-18 mos after fish were stocked. Lighted larval fish traps were deployed at seven reintroduction sites and the Type Locale to determine whether topminnows could reproduce in the presence of the introduced-transplanted Western mosquitofish Gambusia affinis. At stocking sites harboring mosquitofish (n = 12), their density ranged from 0.4 to 66.3 mosquitofish per m2. Annual mortality of stocked Barrens topminnows ranged from 45 to 100% and 24 cohorts experienced annual mortality greater than 95%. Mortality was not related to mosquitofish density or the mean size at stocking. The robustness of Barrens topminnows did not differ in the presence or absence of mosquitofish, suggesting that interspecific competition for food was not occurring. Larval Barrens topminnows were collected at two reintroduction sites and the Type Locale, but juvenile recruits were produced only at sites lacking mosquitofish. The findings of this study, and concurrent laboratory studies, support the hypothesis that mosquitofish predation on larval Barrens topminnows was the primary mechanism in failed reintroductions and is the greatest threat to wild and reintroduced populations of this imperiled species.

American Midland Naturalist↗
USGS2005

Growth, dispersal, mortality, and contribution of largemouth bass stocked into Chickamauga Lake, Tennessee

Marked fingerling largemouth bass Micropterus salmoides (both northern M. s. salmoides and Florida subspecies M. s. floridanus and their hybrid) were stocked into Chickamauga Lake, Tennessee, to enhance angling and introgress the Florida subspecies into the local gene pool. We evaluated mass marking and stocking success by sampling the stocked fish for 1 year poststocking. More than 128,000 fingerlings (35-64 mm total length) were immersed in a solution of 500 mg/L oxytetracycline (OTC) for 6 h and stocked into four embayments in the lake in spring 2002; two additional embayments served as controls and were not stocked (these embayments contained only wild, indigenous fish). In a blind test, 97% of sagittal otoliths were correctly scored as marked or unmarked. In a subsequent test, the OTC marks were clearly visible on every otolith removed from 240 OTC-treated bass held for 30 d. Age-0 largemouth bass were sampled with DC electrofishing gear at 7-19, 44-61, and 119-139 d after stocking, and sampling was conducted along 100-m transects within 1 km of the stocking sites in each embayment. Of all recaptures in the first sample, 31% occurred more than 600 m from the nearest stocking site, indicating rapid dispersal by some fish. Survival of stocked and wild age-0 largemouth bass was similar and low (4.5-6.9%) in two embayments; in the other two embayments, stocked fish survived at lower rates (0-4.3%) than wild fish (33.7-49.9%). Mean catches of all age-0 largemouth bass in the first sample were positively related to the number of fish stocked. By October 2002, the mean catch of all age-0 largemouth bass was similar among embayments. Contribution of stocked fish declined to approximately 2% (2 of 91 fish) the following spring. Cost per fingerling increased from US$0.35 at stocking to $12.00 at 140 d poststocking. Increasing the abundance of largemouth bass was not the primary objective of this stocking effort, but stocked fish will have to survive much better if managers hope to introgress Florida largemouth bass genes into the resident population genome.

North American Journal of Fisheries Management↗
USGS2004

Seasonal movement of brown trout in the Clinch River, Tennessee

We used radiotelemetry to monitor the seasonal movements of trophy-size brown trout Salmo trutta in the Clinch River below Norris Dam, Tennessee, to determine whether establishing a special-regulation reach to reduce fishing mortality was a viable management option. Fifteen brown trout (size range, 430-573 mm total length) collected from the river were implanted with radio transmitters between November 1997 and May 1998. Forty-seven percent of these fish died or expelled their transmitters within 50 d postsurgery. The range of movement for surviving brown trout was significantly larger in fall (geometric mean range = 5,111 m) than in any other season. Four brown trout that were monitored for more than 1 year exhibited a limited range of movement (<2 km) during the winter, spring, and summer, but they made extensive movements (>5 km) during the fall season, presumably to spawn. Brown trout also moved more during the fall than in any other season. Harvest restrictions applied to a specific reach of the Clinch River would reduce the exploitation of brown trout in that reach for most of the year but not during the fall, when many fish undertake extensive spawning migrations.

North American Journal of Fisheries Management↗
USGS2003

Relative contribution of stocked walleyes in Tennessee reservoirs

Since the mid-1950s, fisheries biologists with the Tennessee Wildlife Resources Agency have stocked walleyes Stizostedion vitreum in several tributary reservoirs of the Cumberland and Tennessee rivers to augment declining native stocks; however, the efficacy of these management actions has never been formally evaluated. The contribution of stocked walleyes in four Tennessee reservoirs was evaluated during 1999 and 2000 by marking fry and fingerlings through oxytetracycline (OTC) immersion. Stocking densities were 13-48 fingerlings/ha, and marking efficacy was high for fish marked as fry (mean = 98%; SE = 1.7%) and fingerlings (mean = 99%; SE = 0.6%). Nearly all (94-100%; N = 509) of the age-1 and age-2 walleyes collected in the four reservoirs were OTC-marked. Based on these findings, fingerling walleyes must be stocked annually to sustain the walleye populations in these tributary impoundments.

North American Journal of Fisheries Management↗
USGS2002

Recruitment variation of crappies in response to hydrology of Tennessee reservoirs

Black crappies Pomoxis nigromaculatus and white crappies P. annularis were sampled to index recruitment in seven Tennessee reservoirs (four main-stem and three tributary storage impoundments). Crappie recruitment in tributary storage impoundments appeared to be consistently higher in years of high discharge during the prespawn period (1 January-31 March). A similar relation was found in one main-stem impoundment; however, crappie recruitment in two main-stem impoundments was inversely related to discharge during the spawning period (1 April-30 May), and little recruitment variation was found in the fourth main-stem impoundment. In general, reservoir hydrology appeared to have a stronger effect on crappie recruitment in tributary storage impoundments than in main-stem impoundments, possibly because recruitment was more variable in tributary systems. Thus, it is likely that crappie populations will rarely have strong year-classes simultaneously over a wide geographic area or even within a single watershed.

North American Journal of Fisheries Management↗