The brook trout <i>Salvelinus fontinalis</i> is the only salmonid native to the southern Appalachian Mountains, and is distributed across eastern North America from Canada to Georgia. This species was once abundant in coldwater lakes and streams throughout its range, but environmental disturbances and the introduction of non-native species have drastically reduced the number and sizes of wild populations. Genetic evidence suggests a division at the subspecies level between southern- and northern-derived brook trout populations, with the break between the two forms occurring roughly at the New River watershed. Before the subspecies structure was recognized, brook trout of northern origin were widely stocked throughout the Southeast. The primary objective of this study was to determine the phylogenetic origin of all wild brook trout populations in southwestern Virginia using allozyme markers. Seventy-eight streams believed to contain brook trout in the New, James, Holston, and Yadkin river drainages were sampled by backpack electrofishing. Muscle tissue samples were collected from 916 individuals from 56 populations using a non-lethal biopsy technique. The samples were analyzed by cellulose acetate gel electrophoresis and histochemical staining techniques. Variation at four polymorphic loci, including the diagnostic creatine kinase (<i>CK-A2*</i>) locus, was quantified in terms of genetic diversity and population genetic differentiation. Allele frequencies indicated that 19 populations were of putative southern origin, 5 of northern origin, and 32 of mixed genetic origin. The secondary objective was to determine the geographic distribution of southern- and northern-form brook trout populations throughout the native range using data compiled from all known genetic studies. A map of these data showed that the break between the southern and northern form is sharp, occurring at the New/Roanoke-James watershed divide. Populations from the New River drainage expressed the southern allele at a frequency of 85%, suggesting that their historic native character is southern, and that the presence of northern alleles is due to stocking or stream-capture events. The persistence of the southern form, despite the heavy stocking of northern-derived individuals, may be evidence of an adaptive advantage for the southern form of the species. Existence of adaptive genetic differentiation supports the case for conservation of the southern form of the species in future management of brook trout. / Master of Science

Habitat conditions, use and preference, size-at-age, density and condition were assessed for headwater brook charr (Salvelinus fontinalis) populations in streams in Southern Ontario where water extraction was occurring. Research was divided into two separate, but related studies, conducted during the summer and fall of 2002 and 2004. The first study sought to document the habitat conditions that influence size-at-age and density of age-0 brook charr and to test the hypotheses that: [1] differences in fork-lengths among sites were principally influenced by differences in stream thermal regimes as measured by accumulated thermal units (ATUs), with differences in stream physical characteristics (e.g., water quality, morphology, riparian vegetation) also having significant effects; [2] among-stream differences in flow regimes would significantly influence among-stream differences in age-0 densities, with increases in flow being positively correlated with density; and, [3] length and density would be negatively correlated. Results indicated that differences in temperature, stream site and flow influenced differences in age-0 length and density of brook charr. The effect of temperature, as measured by accumulated thermal units, dominated other influences, providing strong support for the null hypothesis [1] that size differences among sites were primarily driven by differences in the prevailing thermal regime. Some evidence was found to suggest that differences in stream physical characteristics influenced fish size and density, with stream flow affecting both to a moderate degree. Thus while study results provide support for the hypothesis [2] concerning flow-related impacts on age-0 brook charr in headwater streams, changes in flow cannot be considered of prime importance over the range of stream discharge differences (14.3-28.5 L???s -1) observed here. Finally, there was no support for hypothesis [3] concerning the negative correlation between age-0 fork-length and density. The second study investigated the effects of municipal groundwater pumping on stream habitat and the resident brook charr population of Monora Creek, Orangeville, Ontario. Specifically, the study aimed to test the hypotheses that: [1] well-related water extraction was associated with habitat degradation at sites proximate to the extraction point; and, [2] degraded habitat was associated with reduced juvenile and adult brook charr use and preference, reduced occupancy density and reduced condition. Study results indicated significant, although subtle, changes in available habitat as a result of pumping activity, with habitats in areas impacted by groundwater pumping showing significant decreases in hydraulic gradient, stream depth and the availability of under-cut bank and run and pool habitat. Combined, the changes in habitat influenced use, with age-0 densities declining in stream reaches impacted by pumping relative to reaches of the stream not impacted by pumping. When adjusting for the relative availability of groundwater extraction on affected and non-affected habitat, standardized habitat preference indices indicated a significant preference for non-affected stream reaches among age-0 brook charr. Adults evidenced only slight changes in distribution among the available habitats that were seasonally dependent, with reduced densities observed in affected habitats and increased densities in non-affected habitats noted only in the fall. Changes in brook charr condition (weight-length relationship) and mortality were generally not in evidence during the course of this study. Combined, these studies suggest development actions moderating either the thermal or flow regime of streams will have negative effects on population status. Water extraction risks altering habitat in unfavourable ways by interrupting important linkages between flow and temperature that favour growth and density, but that prevent critical physiological thresholds for temperature from being surpassed. Furthermore, the impacts on brook charr populations subjected to moderating pumping appear to relate more to patterns of within stream distribution and habitat use than to any direct measures of fitness such as survival or growth. The latter result suggests monitoring abundance and/or condition alone will not suffice to provide early warning of population stress responses to water extraction activities.

No description available.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

No description available.

No description available.

Nomenclature: Sensitivity to anesthetic clove oil different species of adult fish Sensitivity of breeding fishes of various species (Siberian sturgeon, Brook trout, Black carp- young breeding fishes) for anesthetic clove oil was probed by the tests performed at temperature in the period of stripping (apart from Brook trout and Black carp). The tests were carried out with 17 fish species- with cyprinids (Ide- golden form, Common dace, European Chub, Sneep, Barbel, Grass carp, Black carp, bighead carp), salmonids (Brown trout, Rainbow trout, Brook trout), thymallinae (Grayling), pikes (Northern pike), perches (Pike-perch), sturgeons (Siberian sturgeon, Beluga) and airbreathing catfishes (North African catfish). Using concentration of 0,03ml.l-1 (Brown trout, Rainbow trout, Brook trout, Grayling, Pike, Pike perch, Ide, Dace, Chub, Barbel and Sneep), 0,04ml.l-1 (Grass carp, Black carp, Bighead carp), 0,05ml.l-1 (North African catfish) and 0,07ml.l-1 (Siberian sturgeon, Beluga) the IIb. Phase has been achieved, which is sufficient for manipulation with fishes during stripping. The anesthesia subsided after time period of 10-17 minutes (12 species) at the majority of fishes and at others after interval of 20-26 minutes (5 species). The results confirmed concentrations recommended for salmodis and Grayling (0,025-0,03ml.l-1), sturgeons (0,07ml.l-1), and North African catfish (0,05ml.l-1). At the majority of cyprinids (apart from Grass carp, Black carp and Bighead carp), the concentration used was lower than recommended (0,04-0,05ml.l-1)