Lee F.G. Gutowsky

Occupation, body size and sex ratio of round goby (Neogobius melanostomus) in established and newly invaded areas of an Ontario river

Invasive species represent a challenge because the particular characteristics of a species’ invasion are often unknown before the invasion. To provide some clarity as to how invasive species demographic structure might change as a population advances its range, we compared the proportion of occupied sites, size structure and sex ratio of round gobies in the area where they first invaded with more recently invaded areas at the extent of their range in a river in south-eastern Ontario. We used a standardized angling technique to sample gobies larger than 45-mm total length in the summer and early autumn of 2007. Round goby at the upstream and downstream extent of their range occupied a lower proportion of randomly selected sites, and contained a wider distribution of sizes as well as significantly larger individuals. Sex ratios in all areas were male-biased and the male-to-female ratio was significantly higher in the upstream segment of the river (2.2:1) compared to the area of first introduction (1.4:1). The difference between the newly invaded and the established sites suggests that round goby population structure may be affected by density. The results of this study help us further describe the demographic characteristics of biological invasions whilst examples of population structure and behaviour in gobies and other species provide a basis for generating hypotheses for range expansion.

A moving target—incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.

Diel vertical migration hypotheses explain size-dependent behaviour in a freshwater piscivore

In aquatic organisms, diel vertical migration (DVM) is typically characterized as ascent at dusk and decent at dawn. Often several hypotheses are required to explain the sensory-mechanisms and ultimate causes of DVM. Currently, most of the research focused at the individual level has identified DVM functions as a response to light, feeding opportunities, predator avoidance and bioenergetics in small planktivores. However, there are no studies examining whether DVM hypotheses can explain and predict individual behavioural characteristics in top-level predators. In this study, we test whether bull trout, Salvelinus confluentus, a cold-water pelagic-cruising piscivore, show size-dependent daily and seasonal patterns in DVM consistent with light levels (proximate trigger) and feeding opportunities, predator avoidance and bioenergetics hypotheses. To test these hypotheses, free-swimming bull trout (N ¼ 187, 358e881 mm total length) in a large, temperate reservoir were implanted with depth-sensing acoustic transmitters for 1 year. We found that swimming depths of bull trout were shallowest at night, deepest during the day and showed clear patterns of DVM across all seasons. In line with the predator avoidance hypothesis, large and small bull trout occupied different depths in all seasons except the spring, while the likelihood of depth change for large and small fish varied depending on season and diel period. The greatest depth difference among large and small bull trout occurred in the summer and less so in autumn. In the summer, small bull trout remained at greater depths (w15 m) than larger fish (w 7m ) regardless of diel period. Our results indicate that light is a proximate trigger, and since there is no clear temperature-related bioenergetic advantage to changing depths during winter, feeding opportunities and predator avoidance are the most parsimonious DVM hypotheses to explain body-size-dependent behaviour in this top-level predator.

The influence of water temperature and accelerometer-determined fight intensity on physiological stress and reflex impairment of angled largemouth bass

We examined the influence of fight intensity on physiological stress and reflex impairment in largemouth bass during angling events using rod-mounted accelerometers across two temperatures (12 and 22°C). Temperature was the strongest predictor of physiological stress response, while fight intensity was not a strong predictor.

How Long Is Too Long in Contemporary Peer Review? Perspectives from Authors Publishing in Conservation Biology Journals

Delays in peer reviewed publication may have consequences for both assessment of scientific prowess in academia as well as communication of important information to the knowledge receptor community. We present an analysis on the perspectives of authors publishing in conservation biology journals regarding their opinions on the importance of speed in peer-review as well as how to improve review times. Authors were invited to take part in an online questionnaire, of which the data was subjected to both qualitative (open coding, categorizing) and quantitative analyses (generalized linear models). We received 637 responses to 6,547 e-mail invitations sent. Peer-review speed was generally perceived as slow, with authors experiencing a typical turnaround time of 14 weeks while their perceived optimal review time was six weeks. Male and younger respondents seem to have higher expectations of review speed than females and older respondents. The majority of participants attributed lengthy review times to reviewer and editor fatigue, while editor persistence and journal prestige were believed to speed up the review process. Negative consequences of lengthy review times were perceived to be greater for early career researchers and to have impact on author morale (e.g. motivation or frustration). Competition among colleagues was also of concern to respondents. Incentivizing peer-review was among the top suggested alterations to the system along with training graduate students in peer-review, increased editorial persistence, and changes to the norms of peer-review such as opening the peer-review process to the public. It is clear that authors surveyed in this study viewed the peer-review system as under stress and we encourage scientists and publishers to push the envelope for new peer-review models.

Behaviour and Locomotor Activity of a Migratory Catostomid during Fishway Passage

Fishways have been developed to restore longitudinal connectivity in rivers. Despite their potential for aiding fish passage, fishways may represent a source of significant energetic expenditure for fish as they are highly turbulent environments. Nonetheless, our understanding of the physiological mechanisms underpinning fishway passage of fish is still limited. We examined swimming behaviour and activity of silver redhorse (Moxostoma anisurum) during its upriver spawning migration in a vertical slot fishway. We used an accelerometer-derived instantaneous activity metric (overall dynamic body acceleration) to estimate location-specific swimming activity. Silver redhorse demonstrated progressive increases in activity during upstream fishway passage. Moreover, location-specific passage duration decreased with an increasing number of passage attempts. Turning basins and the most upstream basin were found to delay fish passage. No relationship was found between basin-specific passage duration and activity and the respective values from previous basins. The results demonstrate that successful fishway passage requires periods of high activity. The resultant energetic expenditure may affect fitness, foraging behaviour and increase susceptibility to predation, compromising population sustainability. This study highlights the need to understand the physiological mechanisms underpinning fishway passage to improve future designs and interpretation of biological evaluations.

Smartphones and Digital Tablets: Emerging Tools for Fisheries Professionals

ABSTRACT Smartphones and digital tablets are used to collect data for agricultural, geographical, and medical research. Science professionals find these devices attractive because they contain many useful hardware accessories (e.g., camera, Global Positioning System [GPS], accelerometer) and the capacity to access and customize software applications (apps). To enhance student learning, some educators are also integrating tablets into curricula for both indoor and outdoor course work. Recently, fisheries professionals have begun using these devices for data collection and public outreach and awareness. With new waterproofing technology, cases, and peripheral adapters, smartphones and digital tablets are continually becoming more relevant for data collection and education in fisheries. Here, we synthesize some of the available information on smartphone and tablet use for data collection and education and explore some current uses and future opportunities for these devices in fisheries. Overall, our objectiv...

Seasonal thermal ecology of adult walleye (Sander vitreus) in Lake Huron and Lake Erie

The purpose of this study was to characterize thermal patterns and generate occupancy models for adult walleye from lakes Erie and Huron with internally implanted biologgers coupled with a telemetry study to assess the effects of sex, fish size, diel periods, and lake. Sex, size, and diel periods had no effect on thermal occupancy of adult walleye in either lake. Thermal occupancy differed between lakes and seasons. Walleye from Lake Erie generally experienced higher temperatures throughout the spring and summer months than did walleye in Lake Huron, due to limnological differences between the lakes. Tagged walleye that remained in Saginaw Bay, Lake Huron (i.e., adjacent to the release location), as opposed to those migrating to the main basin of Lake Huron, experienced higher temperatures, and thus accumulated more thermal units (the amount of temperature units amassed over time) throughout the year. Walleye that migrated toward the southern end of Lake Huron occupied higher temperatures than those that moved toward the north. Consequently, walleye that emigrated from Saginaw Bay experienced thermal environments that were more favorable for growth as they spent more time within their thermal optimas than those that remained in Saginaw Bay. Results presented in this paper provide information on the thermal experience of wild fish in a large lake, and could be used to refine sex- and lake-specific bioenergetics models of walleye in the Great Lakes to enable the testing of ecological hypotheses.

Temporal plasticity in thermal-habitat selection of burbot Lota lota a diel-migrating winter-specialist.

In this study, animal-borne telemetry with temperature sensors was coupled with extensive habitat temperature monitoring in a dimictic reservoir, to test the following hypotheses: behavioural thermoregulation occurs throughout the year and temperature selection varies on a diel and seasonal basis, in a winter-specialist diel-migrating fish. Burbot Lota lota demonstrated nightly behavioural thermoregulation throughout the year, with a large seasonal shift between selection for very cold temperatures (<2° C) optimal for reproduction during the spawning period and selection for warmer temperatures (12-14° C) optimal for hunting and feeding during non-reproductive periods. During daylight hours, while L. lota avoided habitats warmer than optimal for reproduction and feeding during the spawning and non-reproductive periods, respectively, active selection was limited to selection for 4-6° C habitat during the prespawning period. Although behavioural thermoregulation explained the night-time migration, behavioural thermoregulation only partially explained daytime behaviour, indicating that diel migration is best explained by a combination of factors. Thus, thermal-habitat selection was a good predictor of night-time habitat occupancy in a diel-migrating species. Together, these results show that thermal-habitat selection by fishes may be important throughout the year and a more seasonally plastic behaviour than previously recognized.

Behavioral attributes of turbine entrainment risk for adult resident fish revealed by acoustic telemetry and state-space modeling

BackgroundFish entrainment through turbine intakes is one of the major issues for operators of hydropower facilities because it causes injury and/or mortality and adversely affects population abundance. Entrainment reduction strategies have been developed based on the behavior of downstream migrating fishes, particularly diadromous species. However, knowledge of the behavior of migratory fishes has very limited application for reducing the entrainment of resident fishes, including several species that represent important recreational and aboriginal fishery resources in reservoirs. In this study, we used fine-scale acoustic telemetry and state-space modeling to investigate behavioral attributes associated with entrainment risk of resident adult bull trout (Salvelinus confluentus) in a large hydropower reservoir in British Columbia, Canada.ResultsWe found that adult bull trout resided longer in the vicinity of the powerhouse and moved closer to the turbine intakes in the fall and particularly in the winter. Bull trout were more likely to engage in exploratory behavior (characteristic of foraging or reduced activity) during periods when their body temperature was lower or higher than 6°C. We also detected diel changes in behavioral attributes, with bull trout distance to intakes and probability of exploratory behavior slightly increasing at night.ConclusionsWe hypothesize that the exploratory behavior in the forebay is associated with foraging for kokanee (nonanadromous form of Oncorhynchus nerka), which have been shown to congregate near the dams of hydropower reservoirs in the winter. Our study findings should be applicable to bull trout populations residing in other reservoirs and indicate that entrainment mitigation (for example, use of deterrent devices) should be focused on the fall and winter. This work also provides a framework for combining acoustic telemetry and state-space models to understand and categorize movement behavior of fish in reservoirs and, more generally, in any environment with fluctuating water levels.