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No description available.

This thesis examines the reproductive cycles of five species of Texas centrarchids: the largemouthed black bass, the black crappie, the bluegill, the redear sunfish, and the striped bass. In this report attention is given to the reproductive cycles of the five species for a period of one year.

The purpose of this study was to compare the simultaneous effects of the water soluble fraction (WSF) of JP-4, a common military and civilian jet fuel, on survival, ventilatory rate, preference-avoidance behavior, and blood enzymes and ions of the bluegill sunfish (Lepomis rnacrochirus) to determine possible interrelationships and which procedures might be most descriptive of sublethal stress. The dynamic 96-h LCSO for WSF JP-4 was 26.2% (percent of the maximum soluble amount of JP-4). A concentration of 5.1% WSF JP-4 caused a detectable shift in ventilatory functions (rate and amplitude); this concentration was equivalent to the 96-h LCOl. Fish did not display a strong preference-avoidance reaction when exposed to WSF JP-4. Some avoidance occurred at 3.5% and 4.9% WSF JP-4. At concentrations near the 96-h LCSO fish appeared to lose their ability to detect WSF JP-4, indicating potential for fish not to avoid lethal levels of WSF JP-4. Few significant changes in whole and serum blood parameters were measured in fish exposed to 13% WSF JP-4; at near lethal concentrations changes were primarily attributed to osmoregulatory failure. Therefore such changes in blood parameters would not be useful to validate or confirm exposure to WSF JP-4. There were few significant changes in gill and liver histology of fish exposed to WSF JP-4 other than an increase in size or number of lipid vacuoles in the liver of exposed fish. / Ph. D.

Bluegill were exposed to 3 and 30 pg/L lindane and 20 and 200 pg/L naphthalene to determine uptake rate constants, K1 depuration rate constants, K2, and bioconcentration factors, BCF. Correlations were determined between lipid normalized and non-lipid normalized BCFs, and between observed Kl, K2 and BCFs and predicted values. The K1 values for both chemicals and concentrations were similar. The K2 values were different (1.04 day~1, 0.46 day 1). Naphthalene was more rapid. BCFs for lindane (315) and naphthalene (98) were different. Lipid normalized BCFs for naphthalene were more variable than non-lipid normalized BCFs. The reverse was observed for lindane BCFs. Predicted K1, K2 , and BCFs were in agreement with observed values.

Glacial lakes, such as those in the Midwest region of the United States, are ecologically and economically important, and they provide a wide range of ecosystem services, such as habitat for wildlife and fishes, flood control and recreational boating. Glacial lakes often support locally important sport fisheries, such as largemouth bass <i>Micropterus salmoides</i> and bluegill <i>Lepomis macrochirus</i>,<i> </i>which are partially dependent on suitable habitat within lakes. Nearshore vegetation is often removed by lakeshore landowners for perceived aesthetics and boat access, or by area managers as a form of indirect fisheries management and invasive species control. The connection between nearshore vegetation and fish population health, though widely studied is somewhat unclear. In the two research chapters of this thesis we attempted to further understanding of the environmental factors that influence vegetation abundance and distribution, how vegetation abundance and distribution influences fish population abundance and size structure, and how young-of-year (YOY) largemouth bass utilize habitats within the nearshore environment. In the first research chapter, we used structural equation modeling (SEM) and data collected by the Indiana Department of Natural Resources to quantify the complexity of relationships among catchment characteristics (e.g., catchment size), lake morphology, water quality, vegetation abundance and distribution, and fish population abundance and size structure. Across multiple lakes, lake productivity was more influential in explaining cross-lake variation of largemouth bass and bluegill proportional stock density (PSD) and largemouth bass catch per unit effort (CPUE) than vegetation. This may be a result of the feedback between phytoplankton production and rooted vegetation production. The models we constructed provide insights into the complexity of environmental variables that influence nearshore vegetation and fish populations. In the second research chapter we used stable isotopes (δ¹³ Carbon, δ¹⁵ Nitrogen, δ¹⁸ Oxygen and δ² Hydrogen) to examine the consistency of habitat use and foraging of YOY largemouth bass within Indiana glacial lakes. We observed spatial variation in stable isotope ratios of YOY largemouth bass between habitat types and sites. Additionally, there were significant, positive relationships between δ¹³C of locally collected potential prey items and δ¹³C of YOY largemouth bass suggesting localized foraging patterns. Later in the summer, as young bass grew in size and likely switched to piscivory, we did not observe similar spatial variation in young bass stable isotopes or spatial relationships between prey and the young bass suggesting more homogeneous foraging patterns. Understanding the habitat use patterns of young bass may allow for more efficient and effective management of the nearshore environment. Overall, a greater consideration for the complexity of relationships between nearshore habitat and fish populations may facilitate more effective management.

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Populations of largemouth bass, Micropterus salmoides, and bluegill, Lepomis macrochirus, were evaluated from five pit-lakes in Muhlenberg County, Kentucky, to determine if accurate proportional stock density (PSD) data can be obtained from a mandatory creel survey. It was hypothesized that the proportion of stock-to-quality (300-400mm) and quality (+400mm) largemouth bass from four years (2007-2010) of creel survey data would be statistically similar to those generated through on-site sampling in 2011. Fish were collected via a combination of gill netting, seining, hook-and-line fishing, and boat-mounted electro-fishing. In two of the pit-lakes, the sampling-generated length frequency data was not significantly different from the creel survey data (Pump Gadj[1]=0.03, P=0.8629, Goose Gadj[1]=0.76, P=0.3850). There were significant differences between creel and sampling data for the other pit-lakes (Big Reno Gadj[1]=5.74 P=0.0166, Airstrip Gadj[1]=14.3 P=0.0002, Lime Gadj[1]=9.81 P=0.0017). At least one of the lakes likely demonstrated significances because of low sample size (Airstrip and/or Lime). Changes in population structure due to modified harvest regulations may be responsible for the significant differences (Big Reno and Lime). Population structures were verified with relative weight, length-at-age, and an assessment of five years of largemouth bass and bluegill PSD data. It appears that creel survey data does accurately reflect that of simple sampling techniques and can help guide management decisions.