The habitat requirements of juvenile Arctic grayling (Thymallus arcticus) were assessed in the Williston watershed, British Columbia, where the population is currently red-listed (critically imperiled). Temperature preferences of juvenile Arctic grayling was assessed behaviorally using a shuttlebox system, and an information theoretic approach analysis of logistic regression models was used to evaluate the influence of environmental factors on the distribution of juvenile Arctic grayling throughout the Williston watershed. Temperature preference of juvenile Arctic grayling did not vary between the two tributaries in the watershed (p = 0.77) and the average preferred temperature was 16.84 ± 0.66 °C (n = 28). Comparisons of the preferred temperature to ambient water temperatures suggested that juvenile Arctic grayling will avoid areas where maximum water temperature is above the preferred temperature. There was a positive association between juvenile Arctic grayling occurrence and stream order (SO) and stream order multiplied by distance from the Williston reservoir (SDRxSO), as well as a negative association with the mean daily water temperature variance (varT) and average water temperature (aveT). Overall these findings suggest that large river systems are important juvenile Arctic grayling habitat and management decision should be made to ensure protection of this habitat throughout the range of this species. --P. ii.
A morphologically unique population of longnose dace was known to exist in the Case & Basin Marsh in Banff, Alberta. These fish were thought to be geographically separated and designated as a distinct sub-species, the Banff longnose dace. The traditional taxonomic traits used for this classification have been called into question and may not have accurately reflected phylogeny but resulted from genotype, phenotype, or a combination of both. I assessed the validity of the Banff longnose dace sub-species classification using molecular genetic techniques. I also used this approach in combination with otolith microchemistry for extant populations of Cave & Basin Marsh longnose dace to determine migration between the Bow River and the Marsh. Historically, two different evolutionary mtDNA lineages (Great Plains and Pacific) of the longnose dace came into secondary contact in the Cave & Basin Marsh. None of these lineages proved to be unique or restricted to the Marsh. Instead haplotypes from both extant and archived Marsh populations were found in several other extant Western North America longnose dace populations. However, current longnose dace collections in the Marsh revealed only the Great Plains lineage the Pacific lineage was not found and appears to have been swamped out and extirpated from the region by the more numerous longnose dace of Great Plains lineage. This suggests that the missing Pacific lineage and the loss of the Banff longnose dace morphotype may be correlated. Irrespective of the causes for the unique morphology, my mtDNA evidence does not support the morphological evidence of a distinct sub-species. Microsatellite DNA analysis revealed extant longnose dace populations from the Bow River and Cave & Basin Marsh were not significantly different from one another. The otolith microchemistry results complemented the genetic findings and indicated connectivity and movement of fish between the Marsh and the Bow River. The lack of concordance between morphology and genetics, demonstrates the importance
The influence of physical and biological factors on juvenile interior Fraser coho (Oncorhynchus kisutch) habitat use was examined within the Horsefly River watershed using three approaches. Otolith microchemistry was used to assess potential movement of juveniles throughout the watershed. This analysis showed evidence of an average of 3.5 movements to different habitats within the Horsefly watershed during the juvenile lifestage. It was not possible to track the location and timing of most of those migrations, but some appear to be the result of a movement into small tributaries in late summer and winter. A microhabitat model was used to determine physical characteristics of habitats where juvenile coho were captured. Low velocity, small stream width, a greater proportion of gravel as substrate, and high instream and overhead cover were strongly related to the distribution of juvenile coho within the streams examined. A behavioural study in an artificial stream channel assessed the type of interactions that occur among juvenile coho. Juvenile interior Fraser coho exhibited little evidence of territoriality, contrasting with published reports of highly territorial juvenile coho behavior in coastal systems. The lack of territoriality of the interior Fraser coho studies, their frequent migrations, and their strong association with cover, all suggest interior Fraser coho exhibit different habitat use patterns than coho in coastal streams. The difference in habitat use and requirements may influence the effectiveness of current management strategies, many of which are based solely on criteria from coastal coho research studies. --P. ii.
Habitat features have been shown to influence salmonid spawning site selection as well as the survival and growth of larval fish throughout incubation. Most studies have been conducted in coastal watersheds, however, and little is known regarding habitat features associated with spawning sites for interior populations of salmon. My study examined factors affecting spawning site selection and incubation success for a population of interior Fraser coho salmon (IFC) (Oncorhynchus kisutch), in McKinley Creek watershed, British Columbia. Ground surveys coupled with radio telemetry were used to identify spawning site locations. An information theoretic approach was used to examine the probability of spawning site use based on habitat features. Incubation of larval fish within in-stream artificial redds allowed for the assessment of survival and growth in different incubation environments. The spawning habitat use of IFC throughout the McKinley Creek watershed was more extensive than previously realized. Hyporheic conductivity, dissolved oxygen, temperature and specific discharge were the best indicators of spawning site selection. Despite significant differences in habitat variables between used and unused spawning sites, survival and growth of larval IFC did not differ between sites maternal effects were greater than incubation habitat features. This study has provided critical information about spawning site selection and the incubation environment of IFC, and has contributed to the understanding of the influence of habitat features on salmonids in interior watersheds.
For salmonids, the smolting process includes substantial morphological, physiological and behavioral changes all of which must coincide to ensure the greatest chance of survival in the marine environment. Therefore, understanding how environmental parameters influence the onset, duration, and termination of smolting can have substantial management implications. I used historical data and a controlled laboratory experiment to investigate the role of both temperature and flow on the timing of migration in Chinook salmon (Oncorhynchus tshawytscha) smolts. An Information Theoretic Model Comparison (ITMC) technique was used to correlate 13 years of historical smolt migration data from the Nechako River in central British Columbia, Canada with data on temperature and discharge from the same period. A combination of temperature experience (accumulated thermal units ATU) and flow discharge were best able to describe the observed migration patterns. In addition, ATU consistently performed better than daily mean temperature suggesting that temperature experience plays a larger role in the migration process than a temperature threshold. In a laboratory experiment, temperature manipulation affected growth and development of physiological smolt characteristics. In addition, fish in tanks with increasing temperature showed earlier movement than those in constant temperature tanks. Flow velocity was not found to have an effect on physiological development of smolt characteristics and did not appear to affect timing of migration in the absence of increasing temperature. However, velocity did influence the pattern of migration, since the presence of a strong, directional flow resulted in a well defined migration event with a clear increase, peak and decrease in movement regardless of the temperature manipulation. Alternatively, fish in experimental tanks without increased flow showed either pulses of movement or no clearly defined movement period. A model similar to the approach for the historical data was used to assess the mo
We used Laser-Ablation-Inductively-Coupled-Plasma-Mass-Spectrometry (LA-ICP-MS) to determine if trace metals deposited in calcified structures could be used to infer the life histories of three different species of fish. We were successful in resolving the movements and age at maturity for an anadromous species, the eulachon ('Thaleicthys pacificus') using both Strontium (Sr):Calcium (Ca) and Barium (Ba):Calcium ratios deposited in otoliths. Stream of residence was identified for a non-migratory freshwater species, the slimy sculpin ('Cottus cognatus') in the Williston Reservoir by matching the chemical fingerprint measured in the otolith to the water chemistries where they were captured. We could not reveal, however, movement of bull trout ('Salvelinus confluentus') in the Morice River watershed. Water chemistry was similar throughout the length of the Morice River and movements within the mainstem of this river, therefore could not be distinguished. We conclude that chemical ratios measured in calcified structures are useful for quantifying life-history in fish providing that sufficient differences exist in the fishes ambient chemical environment. 1Clarke, A. D., Shrimpton, J. M., and Telmer, K. are all contributing authors for: Chapter 2 Life History and Patterns of Movement Between Fresh- and Seawater in Eulachon ('Thaleicthys pacificus'); Chapter 3 Discrimination of Habitat use by Slimy Sculpins ('Cottus cognatus') in Tributaries of the Williston Reservoir using Natural Elemental Signatures; Chapter 4 Movement Patterns of Bull Trout (' Salvelinus confluentus') in the Morice Watershed using Chemical Signatures Deposited Spatially in Fin Rays.
Cortisol has been shown to have a glucocorticoid as well as a mineralocorticoid role in teleosts. The dual role of cortisol, however, was thought to be through a single class of receptor, the glucocorticoid receptor (GR) in teleosts until the recent discovery of the gene for a mineralocorticoid receptor (MR) in this group of fishes. My research objective was to determine if MR has a functional role in ionoregulation and if the changes in MR expression were related to biochemical responses when fish move among waters that vary in salinity. I addressed this research question in two ways. In my first experiment, I transferred rainbow trout from fresh- to ion-poor or salt water. An increase in gill Na⁺, K⁺-ATPase (NKA) activity in salt water was associated with higher NKA α1b subunit mRNA. In contrast, there was little change in gill NKA activity following the transfer to ion-poor water, but mRNA for the α1a subunit was significantly elevated. Gill GR and MR mRNA showed little change when fish were transferred to either treatment, but prolactin receptor (Pr1R) and growth hormone 1 receptor (GH1R) mRNA showed significant changes. In my second experiment, I examined adult sockeye salmon migrating from the ocean to spawning grounds. Gill NKA activity declined consistently during migration, accompanied by significant increases in the gill NKA α1a isoform. Generally, mRNA for gill MR and GR declined during migration to fresh water, but gill Pr1R and GH1R increased - particularly after the fish were in fresh water. These findings suggest that cortisol may have a more limited role in ionoregulation than previously described.
