Distribution, diet, and food availability for young-of-the-year (YOY) largemouth bass (Micropeterus salmoides), YOY bluegill (lepomis macrochirus) and threadfin shad (Dorosoma petenense) were studied to reveal any potential interactions in Patagonia Lake, a 170 ha (265 acre) recreational impoundment in Santa Cruz County, Arizona. Threadfin shad, a forage species, were stocked to enhance the growth of bass. As shad became abundant, limnetic zooplankton declined, reducing the primary food supply of the YOY game fish. Diet analysis showed very little food overlap between YOY gamefish and threadfin shad. Shad ate phytoplankton when zooplankton became scarce, and continued to grow well and reproduce. As zooplankton decreased, YOY gamefish shifted their diets to aquatic insects. After the shift, the gamefish did not grow well. The continuous overgrazing of zooplankton by large numbers of threadfin shad had an impact on the growth of the juvenile largemouth bass and bluegills. This impact may result in weak year classes in the future.

The object of this thesis is to verify Largemouth bass (Micropterus salmoides) as an alternative species to Pikeperch (Sander lucioperca) for fish farming in RAS (Recirculating Aquaculture Systems). Largemouth bass with its good meat quality is comparable to Pikeperch and with its lower sensitivity to stress related to RAS conditions could expand the number of species used in intensive aquaculture. This experiment was split to two parts. In the first part was documented adaptation of Largemouth fingerlings to RAS conditions and artificial feed. After successful adaptation, the second part was started the main experiment. Only 9-16g form pieces were picked from the fish from the first experiment.) The Fish were divided into four groups: Candát 100%, Okounek pstruhový 100%, Candát mix, Okounek mix in three repetitions to nine tanks with capacity of 600 l. Dimensions of these tanks are 101x100x59,5 cm. Each tank was settled by 700 fish. In mixed groups were 350 of Pikeperch to 350 of Largemouth bass in each tank. Second part of experiment lasted 60 days. During that time different parameters of water quality were monitored. Twice a day oxygen, water temperature and once a day pH, NO2- , NH4- were monitored. Every day feeding dosage and mortality were counted. At the end of the experiment all fish were weighed piece by piece to find out the percentage frequency of each weight category in 1 g step. From each tank after every part of the experiment 33 pc of fish were selected and the biometrics were made. Monitored parameters were TL,SL,W and FC, FCR, SGR were counted. Evaluation of outcome and comparison of researched groups pointed to next findings. Largemouth bass showed a slightly smaller growing ability than Pikeperch in RAS. We have to consider a lower water temperature to the end value 21,5°C in system which was set because of Pikeperch sensitivity to bacterial infection and the optimum water temperature for Largemouth bass to 26°C. The experiment proved a high survival of Largemouth bass in groups Okounek 100% 99,86% survival, Okounek mix 99,81% survival. Pikeperch in groups Candát 100% and Candát mix did not exceed 97% in survival. An interesting finding of this thesis proved a positive influence of Largemouth bass to the growth of pikeperch. The group Candát mix had the best results in all monitored parameters TL,SL,W and FC, FCR, SGR.

Largemouth bass (Micropterus salmoides) is one of the species of fish that don´t have a significant position among the species of fish breeded in Czech Republic. However the trend of building aquaculture recirculation systems with warm water comes to the fore. Breeding in these conditions opens up the possibility of introducing new kinds of thermophilic fish species. Largemouth bass definitely belongs to this group. The general factors of successful breeding of largemouth bass are the temperature and purity of the water, the suitable-composed diet and the correct stocking density. This work studies another factor that not only participates in the success of the breeding, but also has influence on the energy expenses of the aquaculture system. It is the effect of photoperiod during breeding. Five experimental groups with three repetitions were created according to the time of lighting (8, 12, 16, 20 and 24 hours of light a day). The experiment lasted 16 weeks. The average water temperature was 24,6 °C. The initial stocking density for all tanks was 20.6 kg . m-3. Fish had an initial average weight of 32.6 +- 2.1 grams. The feed ration was set up at 1% of biomass per day. As a diet were used a floating dry pellets Skretting R-2 Europa 15 F of 2 mm. The feed contained 55 % of protein and 16 % of fat. Fish were fed manually by hand. All groups showed high survival during the experiment (99.4 - 100 %). The best results were achieved by a group of 8 hours with the highest feed conversion (FCR = 0.94 +- 0.06) and the highest growth rate (SWGR = 0.6 +- 0.04 % . day-1). The average individual fish weight of the 8 hour group at the end of the experiment was 64.07 +- 2.82 g. On the other hand, group of 12 hours was the worst with the lowest average individual weight (W= 57.51 +- 1.51 g), growth rate (SWGR = 0.49 +- 0.04 % . day-1) and the lowest feed conversion (FCR = 1.16 +- 0.08). These two groups were significantly different in most production indicators. The pervisceral fat index grew with biomass. The longer the photoperiod, the higher the plasma and ammonia content of lactate. In contrast, glucose content decreased. A longer photoperiod also influenced the higher production of antioxidants.

Spawning time and habitat of largemouth bass, survival of embryos, and growth and food habits of fingerlings were studied in 1968 and 1969 at Wahweap Bay, Lake Powell. Spawning began in mid- to late-April, when mean daily water temperature at nesting depths was 14.4-15.0 Centigrade (58-59 Fahreheit), and continued until mid-June. Most spawning took place on the northeast shore of the bay. Sandstone rubble was the most commonly used bottom type for nesting, either at the base of ledges or around large sandstone boulders. Mean nest depth increased from 1.63 meter to 4.54 meters (5.36 feet to 14.90 feet) in 1968 and from 1.51 meter to 2.93 meters (4.96 feet to 9.60 feet) in 1969, because bass sought the protection of ledges and boulders covered by continually rising water. Nearly all embryos required 4 days to hatch, and survival to hatching was 80.4 percent and 92.2 percent for 1968 and 1969, respectively. Growth of fingerlings was similar in both years and most rapid prior to August 1 in both years. Fingerlings from the 1969 year-class were longer than those from the 1968 year-class before August 21. Total length of bass on August 21 was 68.0 millimeters in both years but 86.5 millimeters and 80.2 millimeters on October 1 in 1968 and 1969, respectively. Growth may have been influenced by total temperature experience during the early part of the growing season but not during the latter part. Fingerlings ate mostly crustaceans, insects, and fish. Size of organisms eaten increased with increase in fingerling length, and fingerling bass fed selectively on larger Crustacea. Numbers of nests located and numbers of young-of-the-year taken in beach-seine catches indicated that the 1968 year-class was stronger than 1969. Estimated numbers of bass per 92.9 meters2 (1,000 feet2 ) seined varied from 0.82 to 3.39 in 1968 and from 0.23 to 2.65 in 1969. An index to year-class strength may be obtained from seine catches at any time of the summer after brood dispersal, but indices obtained in this study must be validated by determing the contribution of each year-class to the creel.

Doctor of Philosophy / Department of Biology / Keith B. Gido / A large scale habitat manipulation was conducted to assess the effects of establishing an emergent macrophyte, American water willow Justicia americana, on littoral reservoir communities. Coves in three large (>1,800 ha) Kansas impoundments were chosen and half planted with water willow. Sampling was conducted during the summer from 2001 to 2004. I found that water willow coves had more complex habitat as well as higher abundance and diversity of fishes, macroinvertebrates, and zooplankton than control coves. However, strong temporal variation in water levels influenced the amount of inundated water willow available in these systems. The effects of water willow on density, growth, condition, and diet of age-0 largemouth bass Micropterus salmoides were assessed. Significantly higher densities of age-0 largemouth bass were found in water willow coves, but growth, condition, and diet did not differ between water willow and control coves. Therefore, water willow was able to support higher abundances of age-0 largemouth bass than control coves without affecting growth, condition, or diet. Characteristics of age-0 largemouth bass from the water willow coves were compared to those from two small impoundments (<80 ha) with abundant macrophyte and healthy largemouth bass populations. Small impoundments had higher densities of age-0 largemouth bass than water willow coves in the three large impoundments, but individuals on average also had lower growth, condition, and fewer fish in their diet. Thus, largemouth bass populations in small impoundments may be more regulated by density dependent factors than populations in large impoundments. Overall, water willow is beneficial to littoral areas, supporting an increase in both abundance and diversity of assemblages. Finally, I used a field experiment to test the inundation and desiccation tolerance of water willow for different depths and durations. Water willow was susceptible to inundation, but resistant to desiccation. My findings provide information that can be used to select candidate reservoirs for water willow establishment based on expected water-level fluctuations.

Recent concern about large initial and delayed mortalities resulting from tournament angling for largemouth bass has indicated that it would be desirable to further evaluate the fate of fish that are released after being captured by angling. This study was designed to evaluate sublethal physiological disruptions caused by hooking stress after largemouth bass were played under standardized conditions (0-5 minutes) and to estimate the time needed for recovery of the homeostatic mechanisms (to 72 hours). Blood lactate was used as a measure of metabolic fatigue; plasma osmolality and chloride measurements were used to evaluate osmoregulatory disturbances and gill ion-exchange; and plasma glucose was used as an index of response to generalized non-specific physiological stress. Fatigue of largemouth bass, as indicated by blood lactate values, increased with playing time (0-5 minutes) and was accentuated by an increase in water temperature. Blood lactate levels continued to increase during recovery up to 8 hours but returned to approximate initial values by 24 hours. Plasma chloride values did not change with playing time (0-5 minutes) at water temperatures of 11-13 C and 28-30 C but increased significantly after 1 minute of playing time at 16-20 C indicating an osmoregulatory disturbance. However, at 11-13 C, the plasma chloride values decreased to below values for controls (0 minute) by 72 hours. At 16-20 C, the plasma chloride levels were nearly normal by 24 hours and were at normal levels by 72 hours. Plasma osmolality increased with playing time at all temperatures indicating an immediate osmoregulatory disturbance. The osmolality values returned to initial levels by 72 hours at the cooler water temperature of 11-13 C. However, at the warmer water temperature of 16-20 C, the osmolality values had not returned to the initial values by 72 hours. Plasma glucose did not change at the cooler water temperatures of 11-13 C and 16-20 C but increased significantly at 5 minutes of playing time at 28-30 C reflecting the metabolic response of this species to warmer water temperature. The glucose values remained high throughout the entire 72-hour recovery period. Smaller bass fatigued faster than larger bass at the higher water temperatures (21-26 C and 28-30 C) as indicated by increased blood lactate values. Smaller bass also demonstrated a faster response in plasma glucose levels, probably as a function of fish size and metabolism. Plasma chloride and osmolality in smaller bass showed a response similar to larger bass with an immediate disturbance in osmoregulatory process of fish as playing time increased. Stress imposed on largemouth bass that were caught by angling was demonstrated by changes in the blood chemistry which indicated that sublethal disruption had occurred in the metabolism and osmoregulation of the fish. Handling or holding fish after capture, as in fishing tournaments, probably produces more stress on the fish than the act of being caught and played by anglers. Angling stress is additive to other stresses already imposed on the fish and could result in increased mortality of released fish if the fish cannot adapt readily. Furthermore, released fish may also be more susceptible to diseases or fungal infections and more vulnerable to predation.

No description available.

The interactions between parasites, hosts, and the ecosystems they live in are complex and diverse. This can make predicting how they will respond to pressures like nutrient enrichment difficult. However, this endeavor is important, due to the far-reaching effects it has on ecosystems functioning, industries like aquaculture, and even human health. Even with the significance of this topic, there are key parts of the picture that have received little research attention. For this reason, I chose to study the effects of nutrient enrichment on parasite-host interactions at two different scales, first investigating the interaction directly between parasites and their host, and then manipulating experimental ponds to look at trophic effects. Using the theory of ecological stoichiometry as a conceptual framework allowed for comparison across the two investigations. In both studies, I used largemouth bass and the macro parasites of their digestive tract as my study system, due to the importance of largemouth bass as sport fish, their high trophic status, and diverse parasite assemblages. My first study examined the effects of eutrophication on parasite-host interactions occurring within the host. It centered on four hypotheses: 1) the nutrient content of different host tissues (infection sites) varies within and across hosts, 2) the nutrient contents of parasite genera differ from that of their host tissue(s), 3) the nutrient contents of parasite genera differ from one another, and 4) nutrient availability within specific host tissues is related to the nutrient content and abundance of parasite genera within tissues. I quantified the nutrient content (carbon (C), nitrogen (N), and phosphorous (P) and their ratios) of parasitic infracommunities in the tissues of the liver, stomach, pyloric caeca, intestines, and visceral mesentery of 30 largemouth bass (Micropterus salmoides). I found stoichiometric variation across host tissues and that fish collection site explained variation in pyloric caeca N:P ratios. Parasitic genera differed in their nutrient content with actively feeding parasite forms having higher %N and lower C:N ratios than encysted/non-reproductive forms. In addition, the %C of both actively feeding parasites varied across organs, and, for one genus, this variation reflected differences in host tissue %C. Finally, I found that the total number of actively feeding parasites in the pyloric caeca increased with that tissue’s N:P ratio. My results suggest that parasites encounter significant variation in nutrient availability within and across hosts, and that this variation can influence the nutrient content and abundance of some actively feeding parasites within specific tissues. To determine if the effects from my first study were a result of nutrient changes to host tissues or if they were an artifact of changes occurring at other trophic levels caused by nutrient addition, I conducted an experimental manipulation of a short trophic system. I applied two treatments, a fertilized treatment and a control, to 14 ponds stocked with largemouth bass. I hypothesized that adding a low N:P fertilizer to the ponds would result in fewer parasites in the pyloric caeca of the bass in accordance with findings from my previous work. Alternatively, I hypothesized that indirect changes to intermediate hosts would be responsible for changes in parasite abundance. To measure the effects of nutrient additions on multiple trophic levels, samples of fine particulate organic matter (FPOM), benthic invertebrates, and vertebrate prey were taken from each pond. Stocked bass were retrieved and dissected to obtain samples for nutrient analysis from their pyloric caeca, and to quantify parasite abundances. My treatment was able to affect the %P, C:N, C:P, and N:P of the FPOM in the ponds. Benthic invertebrate biomass was negatively correlated with FPOM %P. I did not find a direct effect of benthic invertebrates on vertebrate prey species, but fertilized ponds had a smaller decrease in the number of vertebrate prey over the course of the experiment. Counterintuitively, the %N of the pyloric caeca of fish in the fertilized ponds decreased, and the %C and C:N increased in relation to the number of vertebrate prey, but %P did not change. The treatment status of the pond and the nutrients of the pyloric caeca did not affect the number of parasites that were found, but parasite numbers were positively associated with prey fish. This result would suggest the number of intermediate hosts, in this case, prey fish, is the determining factor for parasitic loads in the bass I collected. The indirect effects of trophic interaction and the direct effects of changes to host and parasite dynamics both play important roles in predicting the outcome of eutrophication on disease. The conflicting results of these two studies highlight the need for in-depth knowledge of the systems being affected by nutrient additions.

In most Puerto Rico reservoirs, Largemouth Bass Micropterus salmoides are typically fast-growing with distributions composed of distinct year-classes. Cerrillos Reservoir, however, displays the classic characteristics of a crowded bass population common in temperate lakes and ponds with fish stockpiling into a single modal distribution of slow-growing fish. This developed shortly after stocking in 1997, with the population quickly expanding to carrying capacity. Consequently, relative weight declined from above 100 to about 80 and the population was mostly composed of fish <=350 mm. A protected slot limit (356-508 mm) was implemented; however, limited effort and angler attitudes towards harvest of small bass prevented the success of this regulation, which was subsequently removed. In this dissertation, I examined the efficacy of using targeted management harvests for improving growth, size structure, and condition of Largemouth Bass in Cerrillos Reservoir. I used bioenergetics modeling to simulate the effects of targeted harvests. I predicted annual consumption of stock and quality-sized Largemouth Bass and used these estimates to model the effects of population reduction on consumption and growth of remaining bass. To validate the model, experimental removals of Largemouth Bass from the crowded size classes (200-380 mm) were conducted in 2012 and 2013. In these two years, I removed 20% and 22% of the total biomass, respectively. Following the experimental removals, mean condition of Largemouth Bass increased from 83 to 90, and increases were observed in all Largemouth Bass size categories. The reduction in predator abundance resulted in increased prey availability and smaller size structure of sunfish (Lepomis spp.) and tilapia (Coptodon and Oreochromis spp.) populations. I concluded that reducing Largemouth Bass abundance in Cerrillos Reservoir can move population dynamics toward desired management outcomes, but these actions must continue indefinitely to achieve success and sustainability. Annual management harvests are feasible but impractical, so I recommend increasing angler harvest and implementing management efforts designed to limit recruitment (e.g., shoreline rotenone application) to achieve management goals.

No description available.