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.

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.

In aquatic systems refuge habitats increase resistance to drying events and are necessary for maintaining populations in disturbed environments. However, reduced water availability and altered flow regimes threaten the existence and function of these habitats. To test refuge function I conducted a capture-mark-recapture (CMR) study, integrating citizen science angler sampling into fisheries-independent methods. The objectives of this study were twofold: 1) To determine the contribution of citizen science anglers to improving CMR research, and 2.) to quantify apparent survival of Florida Largemouth Bass, Micropterus salmoides floridanus, in a coastal refuge habitat across multiple years of drying severity. The inclusion of angler sampling was determined to be an effective and feasible method for increasing capture probability. Apparent survival of Florida Bass varied among hydrologic periods with lowest survival when marshes functionally dried (< 10 cm). Overall mortality from drying events increased with the duration of marsh drying upstream.

In fish, maternal stress prior to spawn has been reported to have effects on offspring phenotype. Cortisol, the main glucocorticoid (GC) stress hormone, has been proposed as a potential mediator of such effects because of its organizational role in early teleost development. The present thesis tested whether maternal social stress or treatment with cortisol (as a proxy for maternal stress) prior to spawn affects the cortisol response to stress and anxiety-related behaviours in offspring. In zebrafish (Danio rerio), offspring of dominant females exhibited greater boldness at 6 days post-fertilization (DPF). Interestingly, offspring of females that engaged in social interactions, regardless of the resulting social status of the two females, exhibited greater survival at 1 DPF, a greater fear-related decrease in activity in response to bright light at 6 DPF, and decreased baseline whole-body cortisol content at 0 and 30 DPF. A field experiment with wild largemouth bass (Micropterus salmoides) revealed that maternal cortisol treatment prior to spawn also affected offspring phenotype; offspring of cortisol-treated females had higher masses right after hatch, had greater fear responses, were less bold and less anxious, and exhibited an attenuated cortisol response to an acute stressor. Together, the results of the present thesis suggest that effects of maternal stress prior to spawn on offspring survival, growth, responses to stress, and anxiety-related behaviours are mediated, at least in part, by elevated maternal cortisol but not likely via increased deposition of maternal cortisol into eggs. The effects of maternal stress and cortisol treatment on offspring reported in the present thesis also suggest that maternal stress may prime offspring with adaptive traits to better survive in a stressful environment.

L'Estany de Banyoles, sistema peculiar tant des del punt de vista de la seva formació geològica com de les seves característiques limnològiques, conté actualment una comunitat de peixos profundament modificada respecte de la comunitat original. La perca americana (Micropterus salmoides), introduïda a finals dels anys seixanta del segle XX, és avui una de les espècies dominants en aquesta comunitat, i ocupa sobretot l'hàbitat litoral de l'Estany. Es tracta d'una espècie molt ben estudiada a Nord Amèrica des de diverses disciplines de la biologia i des de fa diverses dècades, cosa que ha comportat que actualment es disposi d'un gran volum d'informació sobre ella. Amb tot, fora del seu continent d'origen ha rebut poca atenció, malgrat l'amplia expansió que ha experimentat arreu del món. En aquesta tesi doctoral s'han abordat, amb un enfocament descriptiu, aspectes fins ara desconeguts per a l'espècie a l'Estany de Banyoles, a la península ibèrica i fins i tot a Europa. Concretament, se n'ha analitzat la condició, el creixement i la demografia, així com les seves variacions temporals. Amb aquesta finalitat, s'ha dissenyat un mostreig composat de deu campanyes de pesca intensives més alguns petits mostrejos addicionals intercalats, mostreig que s'ha allargat des del juliol del 1997 i fins el novembre del 1999. La captura dels exemplars s'ha realitzat mitjançant una tècnica de pesca elèctrica amb una embarcació posada a punt expressament per a aquest estudi, la qual s'ha mostrat considerablement eficient malgrat les dificultats que ofereix el medi. S'ha realitzat un mostreig de marcatge-recaptura basat en la mutilació d'aletes i, en alguns casos, en el marcatge amb pintura acrílica. Només en la darrera campanya (novembre del 1999) s'ha sacrificat una part important de les captures a fi de retirar-ne els otòlits per a la determinació de l'edat. Pel que fa a l'anàlisi de les dades, s'ha aplicat un ampli ventall de mètodes i models per a cada un dels aspectes estudiats, a fi de contrastar-ne els resultats i validar-ne la seva fiabilitat. En el cas de la condició, s'han aplicat mètodes d'anàlisi de la covariància (ANCOVA) i altres mètodes anàlegs, així com, paral·lelament, regressions i anàlisis derivades a partir de la relació longitud-pes. En l'estudi del creixement, s'han realitzat ajustaments de diversos models mitjançant regressions sobre dades de mida a l'edat i sobre dades d'increments de mida observats per interval de temps. També s'han aplicat anàlisis de freqüències de longitud, i, finalment, s'han aplicat mètodes de retrocàlcul a partir dels increments anuals del radi observats en els otòlits. Finalment, en el cas de l'estudi de la demografia, s'han aplicat models de marcatge-recaptura per a l'estimació de la grandària poblacional i de la supervivència, i, a més, s'han ajustat diversos models continus de supervivència sobre aquestes estimacions prèvies. També s'han estimat les capturabilitats associades a la nova tècnica de captura. Per una altra banda, s'ha implementat i realitzat un mostreig sobre la població de pescadors esportius de l'Estany encarat a determinar, bàsicament, la pressió de pesca a què es veu sotmesa l'espècie.Els resultats mostren sobretot una alta estabilitat interanual en tots els aspectes estudiats, que s'explica per l'estabilitat ambiental que, al seu torn, és característica d'aquest ecosistema lacustre. Això reverteix en una longevitat màxima observada que iguala la màxima descrita a la literatura per a l'espècie. Alhora, també s'han descrit fortes oscil·lacions estacionals tant en la condició, com en el creixement, com també en la supervivència, les quals, però, presenten certes diferències en la seva temporalitat, cosa que indica una certa diferenciació en els factors que les regulen. / Banyoles Lake is a peculiar system because its geological origin (karstic lake) and its limnological characteristics. At present day, this lake contains a fish community completely transformed respect of the original community. Largemouth bass (Micropterus salmoides), introduced during the sixties of the XX century, is now one of the dominant species in this community, and it occupies mainly the littoral habitat of the lake. This species has been profusely studied in North America from several disciplines of biology and from several decades ago. So, now there is a big amount of published information about largemouth bass, although introduced populations in other continents have received little attention in spite of his wide expansion around the world.In this work some aspects of the species, till now not well-known for the lake Banyoles population and even for the rest of the Iberian populations and many of the European populations, have been approached with a descriptive focus. Concretely, condition, growth and demography have been analyzed, as well as its temporal variations. With this aim, it has been designed a survey with ten intensive campaigns and some other little additional campaigns. This survey began on July of 1997 and it lasted till November of 1999. Capture was made with a boat electrofishing system specially implemented for this study. This capture technique has proved to be very efficient despite the difficulties of this particular ecosystem. It has been developed a mark-recapture survey based on fin mutilation, and, in some cases, on the use of acrylic dyes for marking. Only in the the last campaign (November of 1999) an important part other capture was sacrificed, in order to extract otholits for age determination. A wide variety of methods and models have been applied for the data analysis, and for each of the aspects studied, in order to contrast the results and validate its reliability. In the case of the condition, the analysis has been conduced with ANCOVA and related methods, as well as regression and related analysis over length-weight data. In the study of growth, several models have been fit at length at age data and at observed length increments. Analysis of length frequencies and backcalculations has also been used. Finally, for the demography description, total abundance and survival have been derived from the mark-recapture models, and after that several continuous survival models have been fit over these previous estimates. Capturabilities related to the new capture technique have been obtained, too. On the other hand, a survey based on anglers interviews has been implemented in order to determinate the fishing mortality for this population. The results show a high interannual stability of all the studied aspects, explained by the ambient stability that is typical of this lake ecosystem. That reverts in a high observed longevity that equal the maximum longevity published for the species. At the same time, strong seasonal fluctuations have been described, in the condition, the growth and the demography. But, these fluctuations have different temporal position along the annual calendar, suggesting that there is a differentiation between their regulatory factors.

No description available.

Data were collected from natural and introduced fishes present in Ferndale Lake, a small (120 ha) sport fishing reservoir in Camp County, east Texas. Levels of pH measured in the lake during the study period ranged from 3.5 to 5.3. Monthly field surveys and experimental manipulations were designed to evaluate quantitatively the signs of stress at various biological levels. Lethal limits to low pH were quantified for largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) to be pH 3.8 and 4.0,respectively. Mean blood pH (+ 1 SD) of 59 bluegill was 7.41 (j 0.16), with no significant difference (P-0.05) among groups from Ferndale Lake and Moss Lake (Cooke Co., Texas) under experimental conditions, even when severe stress was externally apparent. In a dual-trough horizontal pH gradient, bluegill behavioral avoidance was observed at pH levels below 7.0. Individual testing of 40 bluegill in pH gradient of 5.2 to 7.6 resulted in median occupation of pH 7.1,with an interquartile range of pH 6.9 to 7.3. Decreased community structure and population "well being" compared to early studies cannot be attributed entirely to recent acidic condition. Separating potential stress due to lake conditions from that due to heavy biotic predation by sport fishing in a small reservoir is difficult.

Alien fish have been implicated in the decline of Rana draytonii (California red-legged frog) and Pseudacris regilla (Pacific treefrog) populations. Micropterus salmoides (largemouth bass) is a common sport fish that has been introduced into the sympatric range of these two anuran species; however, no studies have investigated the individual influence that this alien fish has on these two species. I conducted M. salmoides control or eradication experiments during a four year study in two ponds within the Transverse Mountain Range of Santa Barbara County, California. Changes in the densities of all life stages of R. draytonii and P. regilla were assessed through repeated visual encounter surveys. In response to the manipulations of the M. salmoides populations there was an increase in the density of both species. For R. draytonii, this salient increase in density was recorded in the larval and metamorph life stages. For P. regilla, a slight, yet steady increase in the density of adult, metamorph, and larval life stages was recorded. My results suggest that M. salmoides can be controlled or eradicated from lentic waterbodies and provides reasonable evidence that the negative effects of this species on R. draytonii and P. regilla populations can be minimized or reversed. The reversal of these effects may translate into increases in the densities and potential recruitment of these two native anurans. Therefore, my results provide tentative support that the control or eradication of M. salmoides where they cohabitate with these two species may be a viable conservation measure for R. draytonii and P. regilla populations. Since my study was performed at a very local scale and all results are strictly observational and descriptive, additional studies should be performed at a larger spatial scale and buttressed with controlled laboratory and field enclosures experiments to identify the causal factors responsible for the identified patterns.

Two species of black bass, smallmouth bass Micropterus dolomieu and spotted bass Micropterus punctulatus, are sympatric in both riverine and impounded sections of the New River, Virginia. Resource use (habitat and diet) by the two species was investigated to determine patterns and extent of resource partitioning between them and how those patterns might differ between lotic and lentic environments. Individual fitness indicators (i.e., growth and body condition factor) were also measured to assess performance of populations of the two species in the study areas. Fitness indicators suggested relatively good performance of both species in both river and impoundment, which implied that competitive pressures were not intense. Diet analyses indicated fairly high overlap in prey types consumed. High fitness combined with considerable diet overlap suggested that food availability was adequate, and that segregation in this impounded river system was not on a trophic basis. The two species were found to segregate spatially, with spotted bass predominant in the impoundment and smallmouth more abundant in the river. Spatial segregation was also apparent within both river and impoundment habitat types. / Master of Science