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Redd surveys are a commonly used technique for indexing the abundance of sexually mature fish in streams; however, substantial effort is often required to link redd counts to actual spawner abundance. In this study, we describe how genetic pedigree reconstruction can be used to estimate effective spawner abundance in a stream reach, using Pacific lamprey (Entosphenus tridentatus) as an example. Lamprey embryos were sampled from redds within a 2.5 km reach of the Luckiamute River, Oregon, USA. Embryos were found in only 20 of the 48 redds sampled (suggesting 58% false redds); however, multiple sets of parents were detected in 44% of the true redds. Estimates from pedigree reconstruction suggested that there were 0.48 (95% CI: 0.29-0.88) effective spawners per redd and revealed that individual lamprey contributed gametes to a minimum of between one and six redds, and in one case, spawned in patches that were separated by over 800 m. Our findings demonstrate the utility of pedigree reconstruction techniques for both inferring spawning-ground behaviors and providing useful information for refining lamprey redd survey methodologies. Le recensement de nids de frai est une technique couramment utilisee pour determiner l'abondance des poissons ayant atteint la maturite sexuelle dans les cours d'eau; un effort considerable est toutefois souvent necessaire pour relier le nombre de nids de frai a l'abondance reelle de geniteurs. Nous decrivons comment la reconstitution du pedigree genetique peut etre utilisee pour estimer l'abondance de geniteurs effectifs dans un troncon de cours d'eau, en utilisant la lamproie du Pacifique (Entosphenus tridentatus) comme exemple. Des embryons de lamproies ont ete preleves de nids de frai dans un troncon de 2,5 km de la riviere Luckiamute (Oregon, Etats-Unis). Si des embryons ont ete trouves dans seulement 20 des 48 nids de frai echantillonnes (ce qui indiquerait 58% de faux nids), plus d'une paire de parents ont toutefois ete detectees dans 44% des vrais nids de frai. Les estimations decoulant de reconstitutions de pedigree donnent a penser qu'il y avait 0,48 (IC a 95% de 0,29-0,88) de geniteurs effectifs par nid et revelent que des lamproies individuelles contribuent des gametes a un minimum d'un a six nids et, dans un cas, ont fraye dans des parcelles distantes de plus de 800 m. Nos observations demontrent l'utilite des techniques de reconstitution du pedigree pour mieux comprendre les comportements dans les lieux de frai et pour obtenir des renseignements permettant de peaufiner les methodes de recensement des nids de frai de lamproies. [Traduit par la Redaction], Introduction Redd surveys are a monitoring tool that is used to index the abundance of sexually mature fish in a stream, and involve counting the number of depressions that are [...]

Abstract: To better appreciate the mechanisms underlying the physiology of the stress response, an oligonucleotide microarray and real-time RT-PCR (QRT-PCR) were used to study gene expression in the livers of rainbow trout (Oncorhynchus mykiss). For increased confidence in the discovery of candidate genes responding to stress, we conducted two separate experiments using fish from different year classes. In both experiments, fish exposed to a 3 h stressor were compared to control (unstressed) fish. In the second experiment some additional fish were exposed to only 0.5 h of stress and others were sampled 21 h after experiencing a 3 h stressor. This 21 h post-stress treatment was a means to study gene expression during recovery from stress. The genes we report as differentially expressed are those that responded similarly in both experiments, suggesting that they are robust indicators of stress. Those genes are a major histocompatibility complex class 1 molecule (MHC1), JunB, glucose 6-phosphatase (G6Pase), and nuclear protein 1 (Nupr1). Interestingly, Nupr1 gene expression was still elevated 21 h after stress, which indicates that recovery was incomplete at that time. [Copyright &y& Elsevier]

Abstract: The present study investigated: 1) the behavioral effects of chronic administration of a serotonin uptake inhibitor (fluoxetine) in juvenile Chinook salmon, Oncorhynchus tshawytscha and, 2) whether chronic administration of fluoxetine alters the behavioral effects of corticotropin-releasing hormone (CRH). Chronic (20 day) treatment with fluoxetine decreased locomotor activity when compared to fish given long-term injections of saline. An intracerebroventricular (ICV) injection of CRH had no effect on locomotor activity following a 20 day intraperitoneal treatment with either saline or fluoxetine. Chronic treatment with fluoxetine also increased the amount of time fish spent near the center of the tank. A similar increase was seen in fish given a chronic intraperitoneal (IP) series of saline followed by an acute ICV injection of CRH. However, the effect was not additive when fish were given chronic IP injections of fluoxetine followed by an acute ICV injection of CRH. These results provide evidence to support the hypothesis that the serotonergic system is involved in mediating locomotor activity and habitat choice in teleosts. [Copyright &y& Elsevier]

When fish perceive stressful scenarios, their hypothalamus-pituitary-interrenal axis is activated resulting in the release of corticotropin releasing hormone, adrenocorticotropic hormone (ACTH), and finally cortisol. The physiologic stress response of fish has most often been linked to the reduced performance of the immune system, with a few exceptions where the immune system is activated. In this report, we tested the hypothesis that oxidative burst activity levels in juvenile Chinook salmon ( Oncorhynchus tshawytscha ) are altered when the fish is presented with a stressor. Fish were subjected to a stressor for 3 h and then allowed to recover for 20 h following the stressor. Plasma and spleens were collected from euthanized fish before the stressor, at the end of a 3 h stressor, and 23 h after the start of the experiment. Plasma was held at −80 °C until cortisol radioimmunoassay analysis was performed to confirm stress. Spleens were held in Dulbecco's Modified Eagle Medium overnight and analyzed the day following collection. Oxidative burst activity was measured in splenic leukocytes after being stimulated with phorbol 12-myristate 13-acetate. We found a significant increase in activated oxidative burst from fish subjected to the stressor as compared to unstressed fish. Speculation is given to ACTH being the leukocyte priming agent in this experiment rather than the cortisol itself. [ABSTRACT FROM AUTHOR]