Jacob W. Brownscombe

Range expansion dynamics of the invasive round goby (Neogobius melanostomus) in a river system

The rates of upstream and downstream range expansion of the round goby (Neogobius melanostomus) were examined in the Trent-Severn Waterway in 2009 and 2010. Relative abundance, demographics, and habitat use were also compared between areas of range expansion and a longer established area to determine how these characteristics varied along the invasion pathway. Round gobies were sampled using an angling removal method in May and August of 2009 and 2010 at 75 sites at each area of range expansion and 25 sites near the center of their range where they first became established in the waterway. Areas of range expansion had initially low abundance and low site occupancy in May 2009 relative to the longer established area. Large increases in abundance and site occupancy were observed over the first summer of occupation, but with limited range expansion. Rapid range expansion was observed during the non-reproductive season at the upstream edge of range. Individuals sampled in the expanded upstream range were small and female biased relative to other range locations. Round gobies also exhibited higher habitat selectivity for rocky substrates at range edges than in the longer established area. These characteristics of seasonal dispersal, biased demographics of dispersers, and high habitat selectivity may be important components of successful range expansion of the round goby in invaded ecosystems.

Remote bioenergetics measurements in wild fish: Opportunities and challenges ☆

The generalized energy budget for fish (i.e., Energy Consumed=Metabolism+Waste+Growth) is as relevant today as when it was first proposed decades ago and serves as a foundational concept in fish biology. Yet, generating accurate measurements of components of the bioenergetics equation in wild fish is a major challenge. How often does a fish eat and what does it consume? How much energy is expended on locomotion? How do human-induced stressors influence energy acquisition and expenditure? Generating answers to these questions is important to fisheries management and to our understanding of adaptation and evolutionary processes. The advent of electronic tags (transmitters and data loggers) has provided biologists with improved opportunities to understand bioenergetics in wild fish. Here, we review the growing diversity of electronic tags with a focus on sensor-equipped devices that are commercially available (e.g., heart rate/electrocardiogram, electromyogram, acceleration, image capture). Next, we discuss each component of the bioenergetics model, recognizing that most research to date has focused on quantifying the activity component of metabolism, and identify ways in which the other, less studied components (e.g., consumption, specific dynamic action component of metabolism, somatic growth, reproductive investment, waste) could be estimated remotely. We conclude with a critical but forward-looking appraisal of the opportunities and challenges in using existing and emerging electronic sensor-tags for the study of fish energetics in the wild. Electronic tagging has become a central and widespread tool in fish ecology and fisheries management; the growing and increasingly affordable toolbox of sensor tags will ensure this trend continues, which will lead to major advances in our understanding of fish biology over the coming decades.

Is there a role for aggression in round goby invasion fronts

The role of aggression as a factor promoting invasiveness remains hotly debated. Increased aggression or a lack of tolerance for conspecifics may promote population spread. Some previous research suggests that more aggressive or bold individuals are increasingly likely to disperse and as such these individuals may be overrepresented at the invasion front. In contrast, it has also been argued that individuals at the invasion front represent the least aggressive or least competitive individuals in the population, as these animals are excluded from established areas. Accordingly, the invasion front should be made up of shy, submissive individuals that exhibit reduced aggression. In this study we explore these alternative predictions by quantifying the levels of intra-specific aggression in the round goby (Neogobius melanostomus), an invasive fish that continues to spread rapidly through the Laurentian Great Lakes region in North America. We collected size matched male round goby from an invasion front as well as from an area with an established population, and we staged resource contests between them. Invasion front fish won 65% of the contests and tended to perform more aggressive acts overall. Invasion front fish were not more active or bold prior to the contest, and used the same types of aggressive displays as fish from established areas. Our results also showed that body size asymmetry was an overriding determinant of competitive outcomes, and that body size rather than individual variation in aggressiveness might be the most important contributing factor determining the composition of round goby invasion fronts throughout the Laurentian Great Lakes and its tributaries.

Canadian Recreational Fisheries: 35 Years of Social, Biological, and Economic Dynamics from a National Survey

ABSTRACTFisheries and Oceans Canada has collected a unique, long-term data set on the social, biological, and economic dynamics of Canadas recreational fisheries. Starting in 1975, these data were collected through mail surveys to recreational anglers at 5-year intervals. A longitudinal analysis revealed that there was an average of 4.5 million licensed anglers catching an annual average of 255 million fish. Release rates were relatively high (53% of fish released on average), with recent survey data (2010) suggesting that release rates had exceeded 60%. Recreational anglers also contribute an average of

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

8.8 billion each year to the Canadian economy. However, recreational angling has become less popular over time, and the average age of participants has increased. The data were also useful for characterizing Canadas fisheries, including species-specific catch and harvest. Canada is one of the few countries to collect such extensive recreational fisheries data at a national scale and to do so at regular...

Does Angling Technique Selectively Target Fishes Based on Their Behavioural Type

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.

Spatiotemporal drivers of energy expenditure in a coastal marine fish

Recently, there has been growing recognition that fish harvesting practices can have important impacts on the phenotypic distributions and diversity of natural populations through a phenomenon known as fisheries-induced evolution. Here we experimentally show that two common recreational angling techniques (active crank baits versus passive soft plastics) differentially target wild largemouth bass (Micropterus salmoides) and rock bass (Ambloplites rupestris) based on variation in their behavioural tendencies. Fish were first angled in the wild using both techniques and then brought back to the laboratory and tested for individual-level differences in common estimates of personality (refuge emergence, flight-initiation-distance, latency-to-recapture and with a net, and general activity) in an in-lake experimental arena. We found that different angling techniques appear to selectively target these species based on their boldness (as characterized by refuge emergence, a standard measure of boldness in fishes) but not other assays of personality. We also observed that body size was independently a significant predictor of personality in both species, though this varied between traits and species. Our results suggest a context-dependency for vulnerability to capture relative to behaviour in these fish species. Ascertaining the selective pressures angling practices exert on natural populations is an important area of fisheries research with significant implications for ecology, evolution, and resource management.

Fine scale spatio-temporal life history shifts in an invasive species at its expansion front

Animal behavior and energy expenditure often vary significantly across the landscape, and quantifying energy expenditure over space and time provides mechanistic insight into ecological dynamics. Yet, spatiotemporal variability in energy expenditure has rarely been explored in fully aquatic species such as fish. Our objective was to quantify spatially explicit energy expenditure for a tropical marine teleost fish, bonefish (Albula vulpes), to examine how bonefish energetics vary across landscape features and temporal factors. Using a swim tunnel respirometer, we calibrated acoustic accelerometer transmitters implanted in bonefish to estimate their metabolic rates and energy expenditure, and applied this technology in situ using a fine-scale telemetry system on a heterogeneous reef flat in Puerto Rico. Bonefish energy expenditure varied most among habitats, with significant interactions between habitat and temporal factors (i.e., diel period, tide state, season). The energy expenditure was generally highest in shallow water habitats (i.e., seagrass and reef crest). Variation in activity levels was the main driver of these differences in energy expenditure, which in shallow, nearshore habitats is likely related to foraging. Bonefish moderate energy expenditure across seasonal fluctuations in temperature, by selectively using shallow nearshore habitats at moderate water temperatures that correspond with their scope for activity. Quantifying how animals expend energy in association with environmental and ecological factors can provide important insight into behavioral ecology, with implications for bioenergetics models.

Consequences of Different Types of Littoral Zone Light Pollution on the Parental Care Behaviour of a Freshwater Teleost Fish

The dynamic shifts in life history traits by non-native populations at an invasion front may be driven by a combination of phenotypic plasticity and micro-evolutionary processes, allowing for appropriate responses to changes in biotic and abiotic factors associated with range expansion. The temporal and spatial scale at which these shifts occur, however, is largely unexplored. We examined the age-specific life-history responses of female round goby (Neogobius melanostomus) across a fine spatial scale by comparing traits of individuals at the expanding front of an invasive pathway with those of individuals living at the previous year’s front. Females in the new front were younger, exhibited higher body condition index and fecundity, and greater reproductive allocation than those living at the previous year’s front. No difference in back-calculated length at age or in seasonal growth increment was found between occupants of the old and new fronts. Age-specific differences in reproductive investment were observed; age-1 females from the new front exhibited greater reproductive effort but similar reproductive allocation, whereas age-2 females showed greater reproductive allocation in the new front, but similar reproductive effort. These age-specific differences may be related to differences in population density and other biotic factors encountered during ontogeny, or to micro-evolutionary processes. Our results demonstrate that fine scale changes in energy allocation towards reproduction through increases in reproductive allocation and fecundity occur at the invasion front, highlight how quickly those shifts can occur at the expansion front, and suggest that such changes in newly colonised areas facilitate range expansion.

Ecology of Exercise in Wild Fish: Integrating Concepts of Individual Physiological Capacity, Behavior, and Fitness Through Diverse Case Studies

Ecological light pollution occurs when artificial lights disrupt the natural regimes of individual organisms or their ecosystems. Increasing development of shoreline habitats leads to increased light pollution (e.g., from cottages, docks, automobile traffic), which could impact the ecology of littoral zones of lakes and rivers. Smallmouth bass (Micropterus dolomieu) engage in sole paternal care, guarding their nest continually, day and night, to protect their developing offspring. Any alterations to their behaviour—either directly because of the response to light or indirectly due to changes in nest predator activity and associated response of the bass—could lead to increased energetic demands for fish that have a fixed energy budget and ultimately reduce reproductive success. To examine this issue, tri-axial accelerometer biologgers were externally attached to nesting smallmouth bass during the egg stage to determine whether light pollution (i.e., dock lights with low levels of continuous light and spotlights with high intensity irregular light simulating automobile traffic) altered behaviour of nesting males relative to control fish. Our study revealed that both types of light pollution increased overall bass activity level compared with the control group. The intermittent light treatment group had the highest activity and exhibited large fluctuations between night and day activity levels. Fish in the continual light treatment group displayed statistically higher activity than the control fish but showed limited fluctuations between day and night activity levels. Our results suggest that continuous or intermittent light sources, common in shoreline habitats that have been developed, have the potential to alter the behaviour and thus energy use of nest-guarding fish. This study contributes to the growing body of literature on the ecological consequences of light pollution in aquatic ecosystems.