Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vii, 113 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references.

No description available.

No description available.

The spatial scale at which populations are genetically structured is of immense interest for the understanding of a species’ ecology and evolutionary biology. This can have important implications for management of resources as well as predicting responses to future change. Rainbow smelt (Osmerus mordax) is an anadromous species with a relatively short freshwater residence time compared to other species with similar life-history strategies. Therefore, while they offer the opportunity to sample distinct spawning aggregations, they also offer an insight into the relative roles of contemporary and historical factors shaping connectivity among marine populations, an area of great interest, and for which further understanding is required. With the use of both mitochondrial DNA and nuclear microsatellite markers, I explored the historical and contemporary factors influencing population structure in smelt. While previous phylogeographic work on this species has resolved two mtDNA lineages dating back to previous glacial episodes, I document the discovery of a zone of contact between these lineages in Newfoundland. This is in addition to the established contact zone in the St. Lawrence estuary, and results in a longitudinal distribution of the races with one race predominating on opposite ends of the species distribution, while the other race is geographically intermediate. Patterns of nuclear genetic variation largely mirror the phylogeographic signals in Newfoundland and suggest a more recent colonization of the Avalon Peninsula as well as implicating a remnant historical signal of colonization of the west coast of Newfoundland from the mainland. In addition, contrasting patterns of genetic diversity and levels of differentiation were apparent between the mainland and Newfoundland and suggest differing scales of dispersal within this species. While the population structure within Newfoundland is most consistent with dispersal restricted to within bays, larger scale biogeographic regions were identified in the mainland range, suggesting dispersal is more common and widespread. In addition, sampling of different run times (i.e. ‘early’ vs. ‘late’) demonstrated the potential for isolation by time when spawning events are separated by a break in activity. Overall, these results shed light into the possible roles of both historical and contemporary factors shaping the dynamics and connectivity among populations.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.

Co-variation in the genetic architecture, and co-localization of quantitative trait loci (QTL), for embryonic developmental rate and age at maturation in male rainbow trout (Oncorhynchus mykiss) was examined. Two lots (September and December spawning) of 2 x 5 (male x female) diallel crosses were performed and the resulting progeny were raised to maturity. Higher incidences of precocious maturation were observed in the September lot fish compared to December lot fish, which was uncoupled to developmental rate. However, precocious maturation and body size was higher in early hatching December lot fish. A genome scan was also completed across 4 linkage groups previously reported to possess embryonic developmental rate QTL and/or age at maturation QTL. No evidence of co-localization of QTL for the two traits was detected. However, the presence of QTL for embryonic developmental rate on RT-8 and RT-24 and one for age at maturation on RT-17 supports previous results.

I examined the influence of cyclic feeding regime on fillet yield and quality and their genetic architecture in rainbow trout (Oncorhynchus mykiss). Two lots of half-sib families produced in September and December were exposed to periods of reduced ration followed by increased ration. Fish fed cyclically reduced rations weighed less and had smaller fillets and body proportions relative to controls. They also had less estimated muscle and visceral lipid but also more proportional visceral mass. Lots and families within lots differed significantly for the majority of traits. Genotypic analysis with 23 microsatellite markers spanning 19 linkage groups detected QTL for all traits over multiple linkage groups that were not necessarily consistent between feeding regime and parental lot. Linkage groups RT-9 and 29 had the largest QTL effects for fillet composition traits and overall body size across the greatest number of parents sampled.

Corn gluten meal (CGM) is a high protein (60% crude protein), highly digestible feed ingredient widely used in diets for salmonids, however its use has been related to reduction in muscle pigmentation possibly due to pigment interaction. Therefore, laboratory scale and in vivo trials were conducted to reduce pigment level in CGM and to assess its effect on fish muscle pigmentation, respectively. In the first chapter, a bench-scale study was carried out to investigate factors that affect bleaching of carotenoids in CGM, using white soy flake flour (WSFF) as a lipoxygenase (LOX) source. Plackett-Burman and Box-Behnken designs were used to screen and optimize factors, respectively. Furthermore, a 12-week growth trial was conducted in order to assess the effects of dietary regular and pigment bleached CGM on growth and muscle pigmentation of rainbow. In the second chapter, a 24-week growth trial was carried out in order to assess the effects of increasing levels of CGM on growth and muscle pigment deposition in rainbow trout. In the third chapter, a bench-scale (10 g) corn wet milling procedure was used to assess the bleaching of carotenoids from CGM during steeping. Studies from this thesis confirmed the negative effects of CGM on fillet pigmentation and highlighted the need for evaluation of muscle quality traits such as colour in response to inclusion of new feed ingredients. Furthermore, this thesis gives insight on how to reduce pigments from corn gluten meal using cost-effective and practical bleaching approaches.

No description available.

A standard methodology was developed for performing avoidance-preference tests, using Rainbow Trout (Salmo gairdneri) as the test organism. Experiments were conducted in a hydraulic channel, 9.15 m long by 0.30 m wide, partly divided along its length, and at a flow depth of 0.30 m. The design combined steep and shallow gradient characteristics. The toxicants investigated included Cu(II), Cr(III) and Cr(VI). The lowest avoidance threshold values were established at 2.1 $ mu$g/l for Cu(II) and 0.0026 mg/l and 0.026 mg/l for Cr(III) and Cr(VI) respectively while avoidance reactions increased with levels of toxicant in the channel. Similar experiments were performed with rainbow trout which were pre-exposed at sublethal levels to the toxicant, in order to assess the influence of toxic pre-exposure to the subsequent fish avoidance response. The length of pre-exposure varied between 7-20 weeks. Avoidance threshold values were correlated with safe levels of toxicant exposure. / Pre-exposed fish exhibited decreasing avoidance reactions compared to non-exposed populations. Increased tolerance to the toxicant, was suggested by the increase in avoidance threshold values with pre-exposure levels. Fish exposed to test concentrations matching their pre-exposure levels, clearly preferred this same concentration over the adjacent lower or higher test concentration. / A two mechanism avoidance model was proposed independent of toxicant used or level of pre-exposure. The toxicant concentration where the second mechanism begins to dominate was referred to as avoidance breakpoint, and was correlated to a MATC level for the toxicant in question. Olfactory responses were proposed to be associated with fish avoidance responses below the avoidance breakpoint, while hypoxic stress along with osmo- and iono regulatory stress appeared to be responsible for driving fish avoidance reactions beyond the avoidance breakpoint. / A clearance period of 7 days was sufficient to allow fish to recover normal avoidance behaviour following pre-exposure to Cr(VI) below the avoidance breakpoint.