Certain aspects of the biology of two species of fish, bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides), and the assessment of fishing pressure upon the sport fishery of Pelican Lake, Uintah County, Utah, a 680 ha warmwater lake, were studied between April 1, 1976 and June 30, 1978. The growth rate of bluegills (sexes combined) was fairly rapid; the mean back-calculated total lengths from ages one through nine were 55, 112, 166, 194, 211, 229, 245, 256 and 259 mm. The growth of largemouth bass was 104, 194, 271, 316, 350, 405 and 416 mm total length for ages one through seven for the combined sexes. Male bluegills matured earlier in life than females. Bluegills spawned continually from the first of June to the first of September, although the peak spawning occurred in June of both years. Gonadal weight to body weight ratios (maturity index) were greatest in the first of June for both male and female bluegills. Fecundity estimates ranged from 1 1,102 mature ova for an age II bluegill to 4 6, 281 mature ova for an age V bluegill. Fecundity estimates for largemouth bass ranged from 4,810 mature ova for a II year old to 31, 719 mature ova for a V year old. Largemouth bass spawned primarily in late May in 1976 and early June in 1977. Angler use of the lake was estimated to be 10,054 angler days fished in 1975, culminating a seven-year increase in use, with subsequent declines in angling to 8,001 angler days in 1976 and 5,027 in 1977. A significant winter fishery developed in 1978. Anglers harvested an estimated 58,277, 44,918 and 22,469 bluegills and 5,791, 2,747 and 4,176 largemouth bass in 1975, 1976 and 1977, respectively. Angler catch rates for bluegills in respective years were 1.520, 1.640 and 1.130 fish/hr and 0.204, 0.094 and 0.213 fish/hr for largemouth bass. Bluegill age groups IV and V and largemouth bass age group III composed the majority of angler harvested fish in 1976 and 1977. Age and size composition of angler harvested bluegills indicated no statistically significant change between 1976 and 1977. Bass harvested by anglers in 1977 were significantly greater in weight than those harvested in 1976. The total annual mortality determined from scale analyses of angler harvested fish was 59.9% for bluegill and 71.6% for bass. A significant number of male bluegills was harvested by anglers in June 1977, the period of peak nesting activity. Anglers released 5,158 bluegills in 1977, of which an estimated 11% (565) were lost to hooking mortality. Of various hook sizes used to assess hooking mortality, number 8 regular shank hooks yielded the highest total mortality (18%). The lowest hooking mortality was with number 6 regular shank jig hooks (0%) and where the leader was cut and the hook allowed to remain (0%). Higher mortality of worm-hooked fish was attributed largely to anatomical location of hooking. Of the total (19) bluegill mortalities, 63% were hooked in the esophagus and 37% in the gill/gill arch. Postwinter population sampling in May 1977 indicated the estimated standing crop weight was 40% less than the prewinter standing crop weight in Au gust 1976. A similar loss in standing crop (37%) was noted in weight from August 1977 to June 1978. The greatest loss in numbers was in young-of-the-year bluegill that suffered an estimated 98% overwinter mortality. Midwinter water quality analyses indicated that anoxic conditions occurred from 2.0 m below the ice to the bottom. An increase in hydrogen sulfide levels was also detected. Recommendations for the fishery were (1) adjustment of the daily bag limit for the bluegill sport fishery with fluctuations in angling use; (2) continuation of a creel census from April 1 through July 31 similar to the design used in this study to annually assess angling use, catch rates, total harvest and the size and age composition of this harvest; (3) stomach analyses of potential predators to assess the overwinter mortality of blue gills; (4) retainment of the current bag limit on largemouth bass with future consideration of utilizing a 12-15-in (305-381 mm) total length limit to increase the numbers of larger, older bass in the population; (5) nonrestrictive use of terminal gear by anglers since hooking mortality of bluegills caught and released by anglers in the summer of 1977 was insignificant; (6 ) no size length restrictions on the bluegills retained by anglers; and (7) consideration of purchasing additional water storage from the irrigation company.

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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.

This study examines spatially continuous sampling data in order to investigate patterns of abundance and distribution of three recreationally important sunfish species (bluegill, redear, and spotted sunfish) along the main-stem of the Peace River, a large softwater river located in southwest Florida. A total of 467 electrofishing transects were sampled biannually from spring 2008 to spring 2010. Sampling sites ranged from the headwaters of the Peace River in Polk County, FL to the oligohaline waters located in Charlotte County, FL. All fish were collected with boat mounted electrofishing gear, and aquatic habitat and physiochemical water quality measurements were recorded at each transect. Pearson's correlation coefficient and conical correspondence analysis were used to interpret relationships between sunfish abundance and associated environmental variables. Results showed that relative abundance of sunfish varied significantly between the upper, middle, and lower basins of the river. Distance from headwaters, conductivity and macrophyte coverage were all significant predictors of relative species abundance. Spotted sunfish were found closer to the headwaters and were positively associated with higher amounts of aquatic vegetation. Redear were most common in the middle basin and were most associated with changes in conductivity. Bluegill were relatively more abundant further downriver where conductivities were higher. Woody debris was strongly associated with fish abundance for all species but did not significantly explain the variance in species composition between locations in the river. The result of this study can be used by fisheries professionals to better manage sunfish populations in the Peace River and other lotic systems.