Studying calcium carbonate (otoliths) and calcium phosphate (fins, scales, bones) hard structure chemistry has numerous applications in the fisheries field for both freshwater and marine environments. The overall thesis objectives were: 1.) to provide an integrated and multidisciplinary approach to understanding the incorporation of trace elements and isotopes into biomineralized hard structures, and 2.) to apply this multidisciplinary perspective in the examination of element marking, stock discrimination, and migration in teleost fish species found within the Canadian Polar North. Varying physiological mechanisms within fishes control the uptake of essential and non-essential trace elements and isotopes during biomineralization processes. Essential life elements such as zinc and magnesium are controlled by their own uptake regulation systems whereas non-essential elements such as strontium and barium are controlled primarily by calcium uptake at the gills driven by internal calcium homeostasis. Secondarily, environmental trace elements compete with calcium and with each other for uptake at the gills. The ability of certain hard structures such as bones, fins, and scales to remobilise calcium and associated calcium-like elements, plays a role in the prolonged high concentrations of strontium that were observed in otolith marking of Greenland Halibut, Reinhardtius hippoglossoides. High doses of strontium chloride resulted in a prolonged expulsion of excess strontium. Strong associations of Dolly Varden Char, Salvelinus malma malma, with groundwater allowed discrimination of populations among studied river systems using otolith strontium and barium, and strontium isotopes. Calculation of otolith strontium freshwater baselines allowed for a quantitative method to examine migration histories of Arctic Char, S. alpinus, in Canada and western Greenland. Migration seaward was related to ease of access to estuary and marine habitats. Easy access to estuaries resulted in migration at a young age and small size whereas longer rivers resulted in a delay of migration to older ages and larger sizes. Understanding the role of fish physiology in association with calcium homeostasis provided a stronger basis for understanding the incorporation and presence of trace elements and isotopes found within biomineralized hard structures. These studies underscore the utility of microchemical studies for elucidating biological phenomena, thus linking the aspects of biology, physiology, and geology. / February 2017