Radiotelemetry was used to investigate detailed movement and summer habitat of brown trout Salmo trutta (size range 157-488 mm TL, n=18) in the Kananaskis River, Alberta. Flows in the Kananaskis River respond to pulsed daily discharge from an upstream hydroelectric generating facility (range 0.15 -25 m 3 s − 1 ). Wetted area available for brown trout doubled during periods of high flow. Fluctuating river levels did not appear to influence the degree to which brown trout moved within the study site. However, there was evidence that brown trout used cover and pools more as discharge increased. During high flow conditions, brown trout used similar depths (63 cm), and significantly lower surface water velocities than during low flow conditions. Brown trout also moved closer to shore into interstitial spaces among woody debris and root complexes during high flow. Pool habitats were used most often compared with all other habitat types combined. Pools with large woody debris accounted for 75% of all habitat observations. Woody debris was used more often than all other cover types. Results of the study indicate that the effects of river regulation on brown trout appear to have been moderated by woody debris in pools and along river banks, which provided refuge from high water velocities during periods of high flow.

Recently, researchers have identified that nonlethal costs of predation may arise not only from lost energy intake but also potentially from increased energetic expenditure. During periods of heightened stress following unsuccessful predation attempts, organisms may remain in an altered physiological state with elevated metabolism for some time. Few studies have quantified these nonlethal energetic costs of predation. We monitored the cardiac response (cardiac output (Q), heart rate (f H ), and stroke volume (SV H )) of largemouth bass, Micropterus salmoides, ranging in size from 200 to 425 mm, to simulated avian predation attempts by great blue heron, Ardea herodias, and osprey, Pandion haliaetus. Fear bradycardia during a 30-s predation attempt varied depending upon the size of the fish and the type of predator. The magnitude of the bradycardia decreased with increasing size of the fish; however, the disturbances were more extreme in response to osprey than to blue heron models. Maximal cardiac disturbance following simulated predation attempts by osprey were consistent among size classes of bass. However, the magnitude of the disturbance following heron predation attempts reduced as the size of the fish increased. Size-specific trends were even more extreme for cardiac-recovery durations. Largemouth bass of all sizes exposed to osprey predation attempts required -40 min for Q and f H and -30 min for SV H to return to predisturbance levels. Although small bass exposed to heron predation attempts required recovery times similar to fish exposed to osprey predation attempts, as the size of largemouth bass exposed to the heron model increased above -300 mm, the recovery time decreased significantly. We conclude that the size-specific response of largemouth bass to different predators is reflective of their ability to assess the risk posed by different predators. In addition, the nonlethal costs of predation can be substantial and should be considered in future bioenergetics models. 709Résumé : Récemment, des chercheurs ont découvert que les coûts non létaux de la prédation peuvent être reliés non seulement à la baisse de l'apport d'énergie, mais aussi à l'augmentation de la dépense énergétique. Durant les périodes de stress important qui suivent des essais infructueux de prédation, les organismes demeurent dans un état physiologique perturbé avec un métabolisme élevé pendant un certain temps. Peu de chercheurs se sont attardés à quantifier ces coûts énergétiques non létaux de la prédation. Nous avons mesuré la réaction cardiaque (rendement (Q), rythme (ƒ H ) et volume systolique (SV H )) chez des achigans à grande bouche (Micropterus salmoides) de 200 à 425 mm à des attaques simulées de prédation par le grand héron bleu, Ardea herodias, et par le balbuzard pêcheur, Pandion haliaetus. La bradycardie causée par la peur reliée à une tentative de prédation de 30 s variait en fonction de la taille du poisson et du type de prédateur. L'amplitude de la bradycardie diminuait en fonction inverse de la taille du poisson et l...

Few studies have been conducted to evaluate the effectiveness of nature‐like fishways, particularly in low gradient warmwater streams with diverse fish communities. We evaluated a nature‐like fishway that was installed to facilitate upstream passage at a low head dam on Indian Creek near Spencerville, Ontario, Canada. A passive integrated transponder (PIT) array was used to quantify attraction and passage efficiency for 391 PIT tagged warmwater fish, represented by seven species. Attraction efficiency for the three most common species, common shiner (Luxilus cornutus), creek chub (Semotilus atromaculatus) and white sucker (Catostomus commersonii), was 63.3%, 83.7% and 65.6%, respectively, and passage efficiencies were 5.1%, 38.4% and 25%, respectively. Creek chub were able to locate the fishway in less time than white sucker and common shiner; however, took longer to successfully pass. Manipulation of creek chub release locations was used to separate issues of attraction and passage and revealed that passage efficiency was highest (76.2%) for those released within the fishway and intermediate for those released at the entrance (42.1%). This multispecies fishway improved stream connectivity, but additional work is needed to fine tune its configuration. Similar projects that engage stakeholders in nature‐like fishway construction are a promising approach for the thousands of small dams that occur on low gradient streams around the globe, but those studies should incorporate a biological evaluation to ensure that attraction and passage efficiency are optimised.

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catch-and-release science has revealed that one of the strongest correlates of mortality for fishes is deep hooking in areas such as the esophagus, gills, or stomach, which is largely influenced by gear choice and angler behavior. circle hooks represent a gear type that has been shown to reduce incidences of deep hooking, but not for all species or fishing methods. The apparent condition-dependent success as well as wide range of circle hook configurations causes confusion for the angling community and challenges for fisheries managers. an online snowballstyle survey (n = 1354 completed) targeting north american anglers that have used circle hooks was implemented to examine stakeholder perspectives, an approach that has the potential to reveal issues and opportunities with respect to circle hook use and implementation as a management tool. our survey identified that respondent perspectives tended to be consistent with scientific literature. Most respondents reported that circle hooks are useful (in terms of enabling capture and shallow hooking) for certain species and types of fisheries/methods, but of little use for others (i.e., low hookup rates). however, a number of respondents identified the need for additional education, particularly related to hook sets. Most respondents were apprehensive about broad-scale regulations requiring circle hooks, but felt that such regulations could be used in specific instances. identifying the factors that influence when circle hooks are effective and the barriers to angler adoption of circle hooks in instances where they are deemed effective represent key research needs. regional or fishery-specific social science surveys based on random sampling are needed to further advance understanding of circle hooks and ultimately lead to a reduction in deep hooking and fish mortality.