Steve M. Sammons

Larval Sampling as a Fisheries Management Tool: Early Detection of Year-Class Strength

Abstract Larvae of black crappies Pomoxis nigromaculatus, white crappies P. annularis, and white bass Morone chrysops were sampled in 1992–1996 from Normandy Reservoir, Tennessee, with a 1 × 2-m neuston net. Larval crappies were not captured in 1992 or 1993, but densities over the remaining three years varied over two orders of magnitude. Larval white bass were collected every year, but densities also varied over two orders of magnitude among years. Larval crappies recruited to the gear at 9 mm total length (TL), but few over 15 mm were collected. Larval white bass recruited to the gear at 7 mm TL and continued to be sampled by the neuston net at lengths up to 35 mm TL. Peak larval crappie density in the neuston net samples was an accurate predictor of geometric mean number of age-1 crappies per hectare 1 year later in midsummer cove samples (r 2 = 0.99, P = 0.0001). Peak white bass density in the neuston net samples was an accurate predictor of geometric mean catch of age-0 white bass in fall gill-net sa...

Effects of reservoir hydrology on reproduction by largemouth bass and spotted bass in Normandy Reservoir, Tennessee

Abstract Age-0 largemouth bass Micropterus salmoides and spotted bass M. punctulatus were collected from Normandy Reservoir, Tennessee, 1992–1996, to evaluate effects of reservoir hydrology and hatching of shad Dorosoma spp. on hatching and first-year growth and survival of these two species. Fish were collected in cove rotenone samples in early Aug and electrofishing samples biweekly throughout the summer; hatch dates and age-specific growth for both species were determined from cove samples with sagittal otoliths. Hatching of both species ranged from early April to early Jun. Initiation of largemouth bass spawning, but not spotted bass spawning, was positively related to the first day water levels achieved full pool. Mean hatch dates of both species were positively related to the first day of full pool. Timing of spawning for both species was not related to water temperature. Largemouth bass exhibited bimodal length-frequency distributions by midsummer in two wet years and length frequencies were unimod...

Population Dynamics of a Reservoir Sport Fish Community in Response to Hydrology

Abstract Sport fish from Normandy Reservoir, Tennessee, were sampled for more than 6 years with a variety of gears targeting different life stages. Normandy Reservoir experienced different hydrologic regimes over the sampling period that we roughly grouped into dry years (1992 and 1995), intermediate years (1993 and 1997), and wet years (1994 and 1996). Year-class strength of largemouth bass Micropterus salmoides was fixed each year by late summer or early fall. Catch of age-1 largemouth bass in spring electrofishing samples was directly related to the number of days the reservoir was at or over full pool when the fish were age 0. Largemouth bass produced in a wet year and intermediate year were more than twice as abundant at age 3 than fish produced in two dry years. Recruitment of spotted bass M. punctulatus could not be linked to reservoir hydrology. Crappies Pomoxis spp., white bass Morone chrysops, and saugeyes (walleye Stizostedion vitreum × sauger S. canadense) produced poor year-classes in dry yea...

Recruitment Variation of Crappies in Response to Hydrology of Tennessee Reservoirs

Abstract 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 wa...

Spatial and Temporal Variation in Electrofishing Catch Rates of Three Species of Black Bass (Micropterus spp.) from Normandy Reservoir, Tennessee

Abstract Largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, and spotted bass M. punctulatus were sampled by electrofishing in the spring and fall for 6 years in Normandy Reservoir, Tennessee, to assess spatial and seasonal differences in abundance. Bass were collected each season from 40 transects stratified among the following habitats: riprap, rubble, gravel, mixed substrate, and coves. A randomized-block design analysis of variance (ANOVA) was used to partition variation by habitat and year. Abundance was greatest in riprap habitats for largemouth bass and smallmouth bass in spring samples. Abundance was greatest in rubble habitats for spotted bass in spring samples, but in only 2 of 6 years. Abundance of largemouth bass and spotted bass was lowest in gravel habitats and cove habitats, respectively; smallmouth bass abundance was uniform and consistently low in all nonriprap habitats. Abundance trends among habitats in fall samples were similar to spring samples for all three species. G...

Early Life History Characteristics of Age-0 White Crappies in Response to Hydrology and Zooplankton Densities in Normandy Reservoir, Tennessee

Abstract Age-0 white crappies Pomoxis annularis were collected in 1994 and 1996–1998 in cove samples from Normandy Reservoir, a 1,307-ha flood control impoundment on the upper Duck River in southcentral Tennessee. Age-0 crappies were measured (TL, mm) and weighed (g); otoliths were removed and hatch dates and daily growth rates determined for the aged fish. Across years, crappies hatched as early as 13 April and as late as 6 June. Hatch date and length-frequency distributions were unimodal in all years. The first hatch date and mean hatch date of white crappies were positively correlated with the first day the reservoir achieved full pool. Growth ranged from 0.41 to 0.90 mm/d; it did not appear to be affected by the density of white crappie larvae but may have been affected by that of crustacean zooplankton. Within each year, earlier-hatched fish grew at slower rates than later-hatched fish, probably owing to the warmer water temperatures experienced by later-hatched fish. However, year-classes that hatch...

Variation in Population Characteristics and Gear Selection between Black and White Crappies in Tennessee Reservoirs: Potential Effects on Management Decisions

Abstract The population characteristics of crappies Pomoxis spp. were examined in three Tennessee reservoirs (Kentucky, Barkley, and Woods) sampled in fall with trap nets and electrofishing. Kentucky and Barkley reservoirs are large main-stem impoundments on the Tennessee and Cumberland rivers, respectively. Woods Reservoir is a small tributary storage impoundment on the Elk River in south-central Tennessee. Mean length at age was similar between white crappies P. annularis and black crappies P. nigromaculatus at ages 1 and 2 in Barkley Reservoir and at age 1 in Kentucky Reservoir. Thereafter, white crappies were consistently larger than black crappies at older ages, and the differences in mean length commonly exceeded 30 mm once the fish in both reservoirs were age 4. Crappie species compositions in concomitant electrofishing and trap-net samples were relatively similar in the two main-stem reservoirs. However, black crappies represented much higher proportions in the trap-net samples than they did in th...

Predictive Evaluation of Size Restrictions as Management Strategies for Tennessee Reservoir Crappie Fisheries

Abstract We evaluated the potential effect of minimum size restrictions on crappies Pomoxis spp. in 12 large Tennessee reservoirs. A Beverton–Holt equilibrium yield model was used to predict and compare the response of these fisheries to three minimum size restrictions: 178 mm (i.e., pragmatically, no size limit), 229 mm, and the current statewide limit of 254 mm. The responses of crappie fisheries to size limits differed among reservoirs and varied with rates of conditional natural mortality (CM). Based on model results, crappie fisheries fell into one of three response categories: (1) In some reservoirs (N = 5), 254-mm and 229-mm limits would benefit the fishery in terms of yield if CM were low (30%); the associated declines in the number of crappies harvested would be significant but modest when compared with those in other reservoirs. (2) In other reservoirs (N = 6), little difference in yield existed among size restrictions at low to intermediate rates of CM (30–40%). In these reservoirs, a 229-mm li...

Initial Poststocking Mortality, Oxytetracycline Marking, and Year-Class Contribution of Black-Nosed Crappies Stocked into Tennessee Reservoirs

Abstract Initial poststocking mortality, oxytetracycline mark persistence, and year-class contribution were evaluated for black-nosed crappies, a morphological variant of the black crappie Pomoxis nigromaculatus, stocked into Tennessee reservoirs during 1997–1999. Average initial poststocking mortality was low (x = 13%, N = 44). Lake temperature and the difference between lake and hauling tank water temperatures were significant in explaining variability in arcsine-transformed mortality estimates; however, the variability explained by these factors was low (R 2 = 0.15). Oxytetracycline immersion was a highly effective marking tool; 97–100% of all crappies treated were marked, and 99% of the marks were visible 36–110 weeks after marking. All control otoliths were correctly scored as unmarked during the evaluation, and mortality rates did not differ between marked and unmarked crappies. Year-class contribution was variable across reservoirs and was highest in Normandy Reservoir (34–93% at ages 1–3). Contrib...

Efficacy of identifying stocked crappies in a Tennessee reservoir through oxytetracycline marking

Abstract Oxytetracycline (OTC) immersion was used to identify black-nosed crappies, a morphological variation of black crappie Pomoxis nigromaculatus, stocked into Normandy Reservoir, Tennessee, during fall 1997. The technique effectively marked 97% of the treated fish. Analysis of one otolith per fish by one reader successfully identified 98% of marked and unmarked fish in a blind test. Marks were formed before annulus formation and were not obscured by annulus-related autofluorescence, suggesting that OTC can be effectively used late in the year (Oct and Nov) in Tennessee.