Relationship of baseline and maximum glucocorticoid concentrations to migration propensity: A field test with wild subadult brown trout (salmo trutta)

There is considerable variation in glucocorticoid (GC) baseline status and stress responses of individuals, yet the cause and consequence of this variation remains ambiguous. Attempts to relate GC levels to fitness and life-history trade-offs have yielded variable results. In this study, we evaluated whether baseline and poststressor GC hormone concentrations predicted migration strategy (

On the Electroimmobilization of Fishes for Research and Practice: Opportunities, Challenges, and Research Needs

As a result of growing demand for immediate-release sedatives in fisheries research, electroimmobilization has been receiving increasing attention due to its superior induction and recovery times and practicality, particularly under field conditions. However, a review of electroimmobilization and its role in fisheries science has not been previously conducted. Here we describe and differentiate the various forms of electroimmobilization and attempt to standardize relevant terminology. We review the known efficacy of electroimmobilization of fish and summarize the current available knowledge on this topic while identifying major knowledge gaps. Although more information is needed to determine optimal forms and settings for different species, life history stages, and environmental variables, electroimmobilization is a useful tool for fish handling that equals or surpasses the capabilities of chemical sedatives without exacerbating (and sometimes reducing) the negative consequences associated with chemical sedatives and fish

Evidence of fish spillover from freshwater protected areas in lakes of eastern Ontario

Research has identified numerous conservation benefits attributed to the use of marine protected areas (MPAs), yet comparatively less is known about the effectiveness of freshwater protected areas (FPAs). This study assessed multiple long-standing (>70 years active) intra-lake FPAs in three lakes in eastern Ontario, Canada, to evaluate their potential conservation benefits. These FPAs were intended initially to protect exploited populations of largemouth bass (Micropterus salmoides (Lacépède, 1802)), but since their establishment no empirical data have been collected to evaluate the effectiveness of FPAs for protecting bass or the broader fish community. A comparative biological census of fish species abundance, biomass and species richness was conducted using snorkelling surveys within FPAs, along the bor

Spatial ecology of reintroduced walleye (Sander vitreus) in Hamilton Harbour of Lake Ontario

Many coastal embayments in the Laurentian Great Lakes have been subjected to extensive human physical modification and pollution that has led to the loss of freshwater biodiversity. For example, Hamilton Harbour is a large coastal embayment situated at the western end of Lake Ontario, wit

Assessing occupancy of freshwater fishes in urban boat slips of Toronto Harbour

Hardening of natural shorelines in urban aquatic ecosystems can result in a loss of fish habitat and productivity. The north shore of Toronto Harbour (Lake Ontario) has been converted to hardened boat slips for commercial, industrial and recreational purposes, but its potential utility as fish habitat has not been evaluated. The objective of this study was to determine whether fish frequented and utilized four slips in the Inner Harbour of Toronto. Two western boat slips are adjacent to some natural features and have undergone some rehabilitation to increase the complexity of aquatic habitat (i.e. addition of large substrate, overhead cover, and in-water structure). In contrast, the two eastern slips are deeper and more influenced by the turbid Don River. We assessed the timing and duration of occupancy within all four slips for seven fish species using acoustic telemetry. In just under a year, tagged fishes spent

Use of Fish Telemetry in Rehabilitation Planning, Management, and Monitoring in Areas of Concern in the Laurentian Great Lakes

Freshwater ecosystems provide many ecosystem services; however, they are often degraded as a result of human activity. To address ecosystem degradation in the Laurentian Great Lakes, Canada and the United States of America established the Great Lakes Water Quality Agreement (GLWQA). In 1987, 43 highly polluted and impacted areas were identified under the GLWQA as having one or more of 14 Beneficial Use Impairments (BUIs) to the physical and chemical habitat for fish, wildlife and humans, and were designated as Areas of Concern (AOC). Subnational jurisdictions combined with local stakeholders, with support from federal governments, developed plans to remediate and restore these sites. Biotelemetry (the tracking of animals using electronic tags) provides information on the spatial ecology of fish in the wild relevant to habitat management and stock assessment. Here, seven case studies are presented where biotelemetry data were directly incorporated within the AOC Remedial Action Plan (RAP) process. Specific applications include determining seasonal fish–habitat associations to inform habitat restoration plans, identifying the distribution of pollutant-indicator species to identify exposure risk to contamination sources, informing the development of fish passage facilities to enable fish to access fragmented upstream habitats, and assessing fish use of created or restored habitats. With growing capacity for fish biotelemetry research in the Great Lakes, we discuss the strengths and weaknesses of incorporating biotelemetry into AOC RAP processes to improve the science and practice of restoration and to facilitate the delisting of AOCs

Comparing Immobilization, Recovery, and Stress Indicators Associated with Electric Fish Handling Gloves and a Portable Electrosedation System

Fish sedation facilitates safer handling of fish during scientific research or fisheries assessment practices, thus limiting risk of injury to fish and reducing stress responses. In recent years, there has been growing interest in using electricity to sedate fish; two methods include (1) lower-voltage, non-pulsed-DC fish handling gloves (FHGs) that tend to only sedate fish while the gloves are touching the animal; and (2) a comparatively high-voltage, pulsed-DC Portable Electrosedation System (PES) that leads to galvanonarcosis. This study compared the physiological consequence

Spatiotemporal ecology of juvenile Muskellunge (Esox masquinongy) and Northern Pike (Esox lucius) in upper St. Lawrence River nursery bays during their inaugural fall and winter

Understanding the spatial ecology of juvenile freshwater fish beyond summer months is an essential component of their life history puzzle. To this end, declines in the natural populations of sympatric Muskellunge (Esox masquinongy) and Northern Pike (Esox lucius) in the upper St. Lawrence River prompted study of spatiotemporal patterns and habitat requirements associated with earlier life stages of these congeneric, freshwater predators in fall and overwinter periods. Over 75 age-0 esocids were tagged and passively monitored using acoustic telemetry in four nursery embayments in fall and winter months from 2015 and 2017 months to elucidate spatiotemporal ecology and test hypotheses related to emigration. Presence, residency, space and habitat use were assessed and modelled against key environmental (i.e. water temperature and level) and biological (total length) covariates using mixed effect models. Muskellunge were found to spend more time in deeper, littoral regions with canopy-forming, submerged aquatic vegetation while Northern Pike aggregated in the deepest, highly vegetated region of their nursery embayment. Results suggest fish may exhibit transitionary movements in fall months and may span outwards into nearshore regions along the main river channel. Studies informing coastal restoration initiatives to increase Muskellunge production are encouraged to assess sympatric habitat use relative to prominent embayment structures and further explore depth partitioning by these young predators. With a substantial influence from water-level regulation on use of nursery habitat, future studies must work in concert with management plans aimed at producing more natural riverine cycles and thus increased recruitment of Esox species