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Predation of fish released as part of conservation aquaculture programs may undermine conservation goals. Identification of factors influencing predation, therefore, can inform management decisions that minimize predation losses. For the endangered Nechako white sturgeon (Acipenser transmontanus Richardson, 1836), the survival of individuals released as part of a conservation aquaculture program is threatened by river otter (Lontra canadensis (Schreber, 1777)) predation. Through the recovery of sturgeon passive integrated transponder (PIT) tags from otter latrines, we set out to quantify the extent of predation, identify spatial patterns in predation including identifying predation hotspots, and understand the timing of predation. The recovery of 3.9% of PIT tags from the hatchery-released sturgeon represents a minimum predation estimate based on several identified factors. The distribution of predation hotspots varied by release cohort, with some consistent hotspots among cohorts. An apparent decrease in predation in recent years was seen in conjunction with fewer live captures and lower release numbers, suggesting some level of density-dependent predation. Results from this study can be used to contribute to management decisions related to Nechako white sturgeon recovery efforts, inform further research needs, and contribute to a growing knowledge of sturgeon predation. Key words: predation, PIT tag, white sturgeon, river otter, latrine, conservation aquaculture, Introduction While sturgeon once coexisted with dinosaurs in the Lower Jurassic (~200 Myr), today they are considered the most endangered group of fish due to their sensitivity to anthropogenic disturbance, [...]

Despite the many studies that have shown minimal health risks to individuals living outside of Japan following the Fukushima Nuclear Accident, there are persisting concerns regarding the consumption of Pacific seafood that may be contaminated with radioactive species from Fukushima. To address these concerns, the activity concentrations of anthropogenic [.sup.134]Cs and [.sup.137]Cs, as well as naturally occurring [.sup.40]K, were measured in Pacific salmon collected from Kilby Provincial Park, British Columbia (BC), in 2013 and from the Quesnel River, BC, in 2014 using low-background gamma-ray spectroscopy. In addition, soil samples and a single roof-debris sample were collected and analysed to provide a record of Fukushima-derived contamination in BC. Cesium-134 was not detected in the salmon samples. Cesium-137 was not detected in any of the sockeye or chum samples, although it was detected in all of the Chinook samples. The weighted average ([+ or -]1[sigma]) [.sup.137]Cs activity concentration in the Chinook salmon collected in 2013 and 2014 was 0.23 (3) and 0.20 (3) Bq/kg fresh weight, respectively. A conservative annual dose estimate for an adult who consumes the average Canadian quantity of seafood per year, contaminated with radiocesium at the maximum concentrations measured in this campaign, was calculated to be 0.054 [micro]Sv per year. Cesium-134 was detected in all but two of the soil samples. A weak positive correlation was observed between presence of [.sup.134]Cs and of [.sup.7]Be suggesting that the [.sup.134]Cs arrived via atmospheric deposition. Cesium-137 was present in every soil sample, although the total radiocesium activity concentrations measured were significantly less than action levels set by Health Canada. Key words: Fukushima, Pacific salmon, dose estimate, low-background gamma-ray spectroscopy, soil, [.sup.134]Cs, [.sup.137]Cs, [.sup.7]Be. Malgre les nombreuses etudes qui ont demontre, a la suite de l'accident nucleaire de Fukushima, que les risques pour la sante des personnes vivant en dehors du Japon sont minimes, des preoccupations demeurent quant a la consommation de poissons et fruits de mer du Pacifique qui pourraient avoir ete contamines par des especes radioactives provenant de Fukushima. Afin de repondre a ces preoccupations, nous avons mesure les radioconcentrations de [.sup.134]Cs et de [.sup.137]Cs anthropiques ainsi que celles du [.sup.40]K naturellement present dans le saumon du Pacifique capture en 2013 dans le parc provincial Kilby, en Colombie-Britannique, et en 2014 dans la riviere Quesnel, egalement en Colombie-Britannique, a l'aide de la spectrometrie gamma a faible bruit de fond. Par ailleurs, nous avons recueilli et analyse des echantillons de sol ainsi qu'un echantillon de debris de toit afi n dresser un portrait de la contamination radioactive issue de Fukushima en Colombie-Britannique. Nous n'avons pas deteete de cesium-134 dans les echantillons de saumon. Pour ce qui est du cesium-137, nous ne l'avons detecte dans aucun echantillon de saumon sockeye ou keta, mais dans tous les echantillons de saumon quinnat. La moyenne ponderee ([+ or -]1[sigma]) de la radioconcentration du [.sup.137]Cs dans le saumon quinnat capture en 2013 et en 2014 etait de 0,23(3) et de 0,20(3) Bq/kg de saumon frais, respectivement. Selon une estimation prudente, nous avons calcule que la dose annuelle a laquelle serait expose un adulte consommant la quantite annuelle moyenne de poissons et fruits de mer au Canada, en supposant que ces derniers soient contamines par le cesium radioactif aux concentrations maximales mesurees dans la presente etude, est de 0,054 [micro]Sv par annee. Nous avons deteete du cesium-134 dans tous les echantillons de sol sauf deux d'entre eux. Nous avons observe une faible correlation positive entre la presence de [.sup.134]Cs et de [.sup.7]Be, ce qui laisse presumer que le [.sup.134]Cs est proviendrait des depots atmospheriques. Le cesium-137 etait present dans tous les echantillons de sol, bien que les radioconcentrations totales de cesium que nous avons mesurees aient ete bien en deca des limites etablies par Sante Canada. [Traduit par la Redaction] Mots-cles : Fukushima, saumon du Pacifique, estimation de la dose, spectrometrie gamma a faible bruit de fond, sols, [.sup.134]Cs, [.sup.137]Cs, [.sup.7]Be., Introduction Following the Fukushima Nuclear Accident (FNA) in 2011, large quantities of fission fragments and nuclear fuel were released into the environment from the damaged Fukushima Dai-ichi Nuclear Power Plant. [...]

Fish mercury (Hg) concentrations have been measured over the last 30-40 years in all regions of Canada as part of various monitoring and research programs. Despite this large amount of data, only regional assessments of fish Hg trends and patterns have previously been attempted. The objective of this study was to assemble available freshwater fish Hg concentration data from all provinces and territories and identify national patterns. The Canadian Fish Mercury Database includes over 330 000 records representing 104 species of freshwater fish collected from over 5000 locations across Canada between 1967 and 2010. Analysis of the 28 most frequently occurring species (>1000 records) showed that the majority of variation in Hg concentrations (when normalized to a standard size) was accounted for by geographic location. Median Hg concentrations increased with trophic level (r = 0.40, p < 0.05), with the highest Hg concentrations found in piscivorous species such as walleye (Sander vitreus), northern pike (Esox lucius), and lake trout (Salvelinus namaycush). The Canadian Fish Mercury Database provides the most comprehensive summary of fish Hg measurements in Canada, and the results indicate that several regionally observed trends in fish Hg concentrations (e.g., Hgbiomagnification and geographic variation) are observed at a national scale. Implications for the effective assessment of changes in fish Hg concentrations in relation to changes in Hg emission regulations are discussed. Les concentrations de mercure (Hg) dans le poisson sont mesurees depuis 30 ou 40 ans dans toutes les regions du Canada, dans le cadre de divers programmes de surveillance et de recherche. Malgre cette vaste quantite de donnees, seules des evaluations regionales des tendances et distributions du Hg dans le poisson ont ete effectuees par le passe. L'objectif de l'etude consistait a regrouper les donnees disponibles sur les concentrations de Hg dans les poissons dulcicoles pour toutes les provinces et tous les territoires et a cerner les motifs de distribution a l'echelle nationale. La base de donnees canadienne sur le mercure dans le poisson (' Canadian Fish Mercury Database ') comprend plus de 330 000 entrees representant 104 especes de poisons dulcicoles echantillonnes dans plus de 5000 localites a la grandeur du pays, de 1967 a 2010. L'analyse des 28 especes les plus frequentes (>1000 entrees) a demontre que la situation geographique expliquait la majeure partie de la variabilite des concentrations de Hg (normalisees en fonction d'une taille standard). Les concentrations medianes de Hg augmentaient parallelement au niveau trophique (r = 0,40, p < 0,05), les poissons piscivores comme le dore (Sander vitreus), le grand brochet (Esox lucius)etle touladi (Salvelinus namaycush) presentant les plus fortes concentrations. La base de donnees canadienne sur le mercure dans le poisson constitue la synthese la plus exhaustive des mesures de Hg dans le poisson au Canada, et les resultats indiquent que plusieurs tendances observees a l'echelle regionale des concentrations de Hg dans le poisson (p. ex. bioamplification et variations geographiques du Hg) sont egalement observees a l'echelle nationale. Les consequences de ces resultats en ce qui concerne l'evaluation efficace de l'evolution des concentrations de Hg dans le poisson par rapport aux modifications de la reglementation en matiere d'emissions de Hg sont abordees. [Traduit par la Redaction], Introduction Anthropogenic activities have contributed to the increase in the global atmospheric mercury (Hg) pool during the 20th century (Pacyna et al. 2010). In Canada, with the exception of known [...]

Canada, internationally praised for its natural beauty and strong environmental legislation to protect its terrestrial, aquatic, and marine ecosystems, is undergoing a legislative makeover. With extraction of natural resources in [...]