Study to determine the seasonal changes in histological and cytological structures in the testis of Huro Salmoides (Lacepede), the large-mouthed black bass.

Copper exposures of 400 μg/L for 5,10 and 15 days resulted in no significant differences in antibody titers of largemouth bass, Micropterus salmoides injected with Aeromonas hydrophila compared to control-injected bass. Twenty days of exposure did significantly increase titers. The control group had significantly lower antibody titers than either control-injected or copper-exposed.

No description available.

Observed growth in weight of an individual fish is the result of an interaction between the environment and the fish's bioenergetic system. A species-specific model is presented which simulates the bioenergetics and growth of largemouth bass (Micropterus salmoides). The model is used to simulate individual growth with changes in the annual temperature regime and relative levels of prey availability. Interaction among temperature, prey availability, and individual size are examined with the model in terms of their influence on growth. Preliminary tests with the model produced an exponential long term growth pattern which is contrary to the conceptualized trend of individual fish growth. Larger weights are produced by a southern temperature regime because of a longer growing season. Variations in the relative abundance and state of availability suggests an unstable system at limiting levels. Analysis of the interaction between temperature and prey availability indicates a stable maximum growth temperature above limiting levels of prey availability while the temperature range for positive growth narrowed as prey availability declined. At limiting prey levels, the temperature range for positive growth narrowed and maximum growth temperatures declined as individual size increased in the temperature-individual size interaction. The model is tested against observed growth data for the 1975 year class of largemouth bass inhabiting West Point Reservoir, Alabama-Georgia. Simulated weights underestimate the observed weights for the first and second years by 25% and 21%, respectively. An alternative equation for caloric density is developed and employed to improve the model's reality and accuracy. / M.S.

Briery Creek Lake (BCL) has low abundance of young largemouth bass (LMB) compared to Sandy River Reservoir (SRR), which could jeopardize the trophy-LMB management goal in BCL. I assessed factors that may limit recruitment of LMB in BCL: angling, predation, competition, growth, and food availability. Age-0 LMB were monitored from nesting through their first summer with nest surveys, light traps, and electrofishing. Nesting success was higher in BCL (53%) than SRR (31%). Initial light trap catch-per-unit-effort (CPUE) was higher in BCL than SRR but, by July, light trap and electrofishing CPUE was higher in SRR than BCL. LMB nest success, growth, and CPUE did not differ between areas in BCL that were experimentally closed and areas left open to angling. Predation on age-0 LMB did occur in BCL, but was not higher than predation in SRR. Diet overlap between age-0 LMB and bluegill in BCL was >60% during June, indicating potential for competition. Zooplankton samples indicated that density of copepods was similar between reservoirs (2.3/liter); however, the average size of copepods was smaller in BCL (0.42 mm) than SRR (0.71 mm). I examined the activity of trypsin, which digests and converts protein. Trypsin activity was lower in BCL than SRR on 23 and 27 June, indicating that a nutritional deficiency exists for age-0 LMB in BCL. This deficiency was likely caused by the reduced zooplankton size in BCL and led to slower growth of age-0 LMB during June in BCL (0.8 mm/day) than SRR (1.2 mm/day). The fact that age-0 LMB CPUE in BCL dropped lower than SRR by July, despite BCL having a greater nesting success and higher CPUE in early June, indicates that a recruitment bottleneck for LMB occurred in June. Maintaining the trophy LMB fishery in BCL requires management options that consider the factors in June that affect recruitment. I recommend decreasing the presently overabundant aquatic macrophytes in BCL, thus allowing for increased nutrient availability for phytoplankton, the primary food source of zooplankton. This could increase the density and size structure of zooplankton, and thereby increase food availability for age-0 LMB. / Ph. D.

Aquatic vegetation is considered a nuisance in many lakes and reservoirs supporting largemouth bass populations, and control (eradication) of vegetation is often undertaken. Yet, the relationship between submerged aquatic vegetation and adult largemouth bass, from a trophic standpoint, is poorly understood. I attempted to quantify this relationship by comparing available prey with consumption from the perspective of individual largemouth bass and the largemouth bass population in Flat Top Lake, West Virginia in 1986 and 1987. The abundance of largemouth bass ≥200 mm long was positively associated with vegetation density, although no relationship was apparent between the length and relative weight of adult largemouth bass and vegetation. Forage fish abundance was also positively related to vegetation density. Vegetation was heavily utilized by most fish species in the reservoir. Consumption (quantity and diet composition) of individual largemouth bass did not differ among the vegetation densities considered. However, the increased abundance of available prey associated with increased vegetation densities led to increased overall consumption by the largemouth bass population. Thus, largemouth bass production potential was positively related to vegetation density. Increases in the vegetation/open water interface had no short-term (one month). Evidence from this study indicates that aquatic vegetation could be managed to increase the productivity of largemouth bass in Flat Top Lake. The benefits to largemouth bass provided by aquatic vegetation in Flat Top Lake and similar systems should be considered prior to initiating vegetation control activities. / Master of Science

No description available.

A total of 192 largemouth bass were caught at Lake Ray Roberts, Texas (1995) to investigate five controversial bass angling techniques relative to hooking mortality. The bait types were Texas-rigged scented and non-scented plastic worms, Carolina-rigged scented and non-scented plastic worms, and live golden shiners. Overall hooking mortality was 21.87% and mortality was dependent upon bait type. Highest mortality resulted from the Texas-rigged scented lures, while the lowest mortality was generated by live golden shiners. A creel survey indicated that few anglers were having success with the investigated baits. Factors that had a confirmed effect on hooking mortality were hooking location and water temperature. Hooking mortality was not excessive compared to other similar studies.

Estuaries serve as nursery areas for a large number of estuary-associated fish species. Some of these taxa also use river catchments as nursery areas. During the upstream migration of this latter group, the juveniles are prone to predation by native and alien predatory fish inhabiting the system. The rate of invasion of ecosystems by alien organisms can be directly linked to anthropogenic influences, including both intentional and unintentional introductions by alien organisms into new regions. The largemouth bass, Micropterus salmoides, is a facultative piscivorous fish that has been successfully introduced worldwide for the main purpose of sport fishing. Where introduced, it has been found to negatively impact native fish and invertebrate species through predation, competitive exclusion and displacement of indigenous fish species. The aim of this thesis was to investigate the predatory impact of largemouth bass on the estuary-associated Cape moony Monodactylus falciformis, Cape stumpnose Rhabdosargus holubi and freshwater mullet Myxus capensis in the lower Kowie River of the Eastern Cape Province, South Africa. A combination of approaches was employed during this study. Stomach contents, stable isotopes and fatty acid analyses were employed for the reconstruction of the diet of largemouth bass. Acoustic telemetry was used to elucidate largemouth bass movements, particularly their ability to enter the upper reaches of the Kowie Estuary. Stomach contents and stable isotopes analyses showed that M. salmoides exhibit an ontogenic shift in diet, with small and medium sized individuals consuming the higher proportion of fish prey, while large sized individuals mostly consumed invertebrates such as crabs (Potamonautes sidneyi) and Odonata larvae, while consuming only a small proportion of estuary-associated fish. Fatty acid analysis only showed a direct connection between the fatty acid profiles of largemouth bass and those of M. capensis and M. falciformis. The acoustic telemetry results indicated that some M. salmoides individuals periodically move into the upper reaches of the estuary following river flood events. The results obtained from all these approaches highlight the risk posed by largemouth bass introductions on indigenous fish species, particularly those that enter the areas occupied by these top predators.

No description available.