Behaviour Of Salmon Research Articles

3-D Visualization of Atlantic salmon skin through Ultrasound and Photoacoustic Microscopy.

Three-dimensional photoacoustic imaging (PAM) has emerged as a promising technique for non-invasive label-free visualization and characterization of biological tissues with high spatial resolution and functional contrast. The application of PAM and ultrasound as a microscopy technique of study for Atlantic salmon skin is presented here. A custom ultrasound and photoacoustic experimental setup was used for conducting this experiment with a sample preparation method where the salmon skin is embedded in agarose and lifted from the bottom of the petridish. The results of C-scan, B-scan, and overlayed images of ultrasound and photoacoustic are presented. The results are then analyzed for understanding the pigment map and its relation to salmon behavior to external stimuli. The photoacoustic images are compared with the optical images and analyzed further. A custom colormap and alpha map is designed and the matrices responsible for PAM and ultrasound are inserted together to overlay the ultrasound image and PAM image on top of each other. In this study, we propose an approach that combines scanning acoustic microscopy (SAM) images with PAM images for providing a comprehensive understanding of the salmon skin tissue. Overlaying acoustic and photoacoustic images enabled unique visualization of tissue morphology, with respect to identification of structural features in the context of their pigment distribution.

Downstream Migration Success of Atlantic Salmon Smolts in a River Catchment Highly Fragmented by Hydroelectric Impoundments

ABSTRACTRiverine habitat fragmentation by barriers, including impoundments, is common and their effects on obligate aquatic organisms are manifold. Organisms, such as Atlantic salmon (Salmo salar), that make extensive river migrations are particularly vulnerable to the effects of impoundments. In this study, we use acoustic telemetry to examine the migratory behaviour of Atlantic salmon, as they migrate to sea for the first time as juvenile ‘smolts’, in a river with a series of dams that form a complex hydropower scheme. We demonstrate that overall migration success in the River Dee catchment and particularly through standing waters was remarkably high. We speculate that high migration success in standing waters could be due to relative current speeds providing good quality directional cues to migrants. Migration success past the two dams in this study, was relatively high, although the number of unsuccessful passage attempts before a successful passage was also very high. The vast majority of smolts passed the dams when the turbines were operational. At one dam, smolts did not use an available fish pass but migrated through the generating turbines. These findings provide several routes through which generation could be managed to enhance the success of downstream smolt migration in rivers where there are similar patterns of hydrogeneration in place.

Understanding how winter conditions in the North Atlantic affect the physiology and behaviour of Atlantic Salmon in sea-cages

In recent years there have been a number of instances where declines in water temperature are suspected to have contributed to winter mortalities at salmon cage-sites in Atlantic Canada. In addition, it is expected that temperature variability due to more intense and frequent winter storms will increase with climate change, and this may further threaten Atlantic salmon health and welfare in sea-cages. To better understand cage-site conditions and aspects of salmon behaviour and physiology during the winter, we fitted Atlantic salmon in commercial size sea-cages in Newfoundland (Canada) for two consecutive years with internal and external data storage tags (DSTs) that recorded depth, temperature, heart rate (fH) and 3D-acceleration (swimming activity). Tags were surgically attached / implanted in late October / early November when water temperatures were 8–10 °C, and the DSTs were collected at the time of harvest. Although tag retrieval was limited due to some early mortality, challenges due to Covid-19 and with fish identification during harvest, the data collected for both years were comparable.Water temperature decreased at a rate of 0.35–0.57 °C week−1 from October / November to March, and the coolest average weekly temperature experienced by the fish was 1.10 °C in early March of both years. Average fH decreased with temperature starting in the fall, and the fish primarily occupied the upper 5 m of the cage for the duration of this study, despite the fact that temperatures were generally homogeneous with depth. Nonetheless, vertical migrations to deeper depths were observed during some periods (e.g., at night during the coldest months), and thus, the average depth of the fish was greater during these times.These data reveal that temperatures in sea-cages in Newfoundland remain below 5 °C for ~5 months and are below 2 °C for ~1.5 months. Thus, understanding how cold temperatures affect various aspects of salmon biology, and monitoring these fish during this period, is critical to the sustainability and future of this industry.

Evaluating Pacific salmon swimming behavior in the aft end of a pelagic trawl to inform bycatch reduction device design and use

AbstractObjectiveAlthough the bycatch of Pacific salmon Oncorhynchus spp. is relatively low in the Walleye Pollock Gadus chalcogrammus and Pacific Hake Merluccius productus pelagic trawl fisheries, different efforts are employed to reduce it, including the use of bycatch reduction devices (BRDs) that retain the targeted species and provide Pacific salmon a pathway to escape. The objective of this study was to evaluate Pacific salmon behavior inside a pelagic trawl and to determine what conditions favor the probability of a salmon moving forward in the trawl and increase their probability of escapement.MethodsWe placed a video camera at the entrance of the cod end and recorded the behaviors of Pacific salmon as they passed by. The timing of the forward movement Pacific salmon in relation to fishing operations and the correlations between forward movement of Pacific salmon and vessel speed over ground, water flow rate, ambient light levels, and abundance of Walleye Pollock were examined.ResultOf the 2969 Pacific salmon observed, 71% were moving aft toward the cod end, 24% were observed moving forward, and 5% were moving aft then forward or forward then aft. The percentage (77%) and rate (0.86 fish per minute) of forward‐moving Pacific salmon was greatest once the trawl doors were back on the vessel and water flow within the trawl was reduced. Speed over ground and Walleye Pollock abundance were negatively correlated with forward movement of Pacific salmon. Only 6.5% of Pacific salmon that were in the cod end when fishing ended were able to move forward before the cod end was on the vessel.ConclusionPacific salmon can move forward in the trawl throughout fishing operations and haulback, but the percentage increases as the speed over ground and water flow inside the trawl is reduced. The low percentage of Pacific salmon that move forward after fishing has ended suggests that Pacific salmon escapement at the end of a tow is relatively low and suggests that BRD design should focus on stimulating escapement at the first BRD encounter.

A comparison of acoustic tag sizes on wild Atlantic salmon Salmo salar L. smolt migration success and behaviour

AbstractTracking of animal migrations using telemetry technologies needs to take into consideration the burden that the tag exerts on the animal. Here, we examined the potential impacts of acoustic tags of two sizes (nominally a ‘V6’ [smaller] and ‘V7’ [larger]) on the downstream riverine migration success and behaviour of wild Atlantic salmon (Salmo salar L.) smolts. One hundred fish were tagged with either a V6 or V7 tag. Tag burden (tag: fish weight) ranged from 1.88% to 7.39% and differed significantly between fish tagged with the V6 (mean [SD] = 3.63% [0.51%]) and the V7 tags (mean [SD] = 5.84% [0.95%]). There was no significant difference in the in‐river migration failure between the two groups when tested with a time‐to‐event analysis. There were also no differences in other elements of the migratory behaviour (rate of movement, time of detection and residency time) between the two tagging groups. These data support the use of acoustic tracking for monitoring smolt migration and highlight that tagging of smaller smolts at up to 7.39% tag burden to gain a more representative understanding of migration success and behaviours across a smolt population.

Inshore and offshore marine migration pathways of Atlantic salmon post-smolts from multiple rivers in Scotland, England, Northern Ireland, and Ireland.

The migratory behavior of Atlantic salmon (Salmo salar) post-smolts in coastal waters is poorly understood. In this collaborative study, 1914 smolts, from 25 rivers, in four countries were tagged with acoustic transmitters during a single seasonal migration. In total, 1105 post-smolts entered the marine study areas and 438 (39.6%) were detected on a network of 414 marine acoustic receivers and an autonomous underwater vehicle. Migration pathways (defined as the shortest distance between two detections) of up to 575 km and over 100 days at sea were described for all 25 populations. Post-smolts from different rivers, as well as individuals from the same river, used different pathways in coastal waters. Although difficult to generalize to all rivers, at least during the year of this study, no tagged post-smolts from rivers draining into the Irish Sea were detected entering the areas of sea between the Hebrides and mainland Scotland, which is associated with a high density of finfish aquaculture. An important outcome of this study is that a high proportion of post-smolts crossed through multiple legislative jurisdictions and boundaries during their migration. This study provides the basis for spatially explicit assessment of the impact risk of coastal pressures on salmon during their first migration to sea.

Consumer Perceptions of the Canadian Salmon Sector and Their Associations with Behaviors: A Perspective from Indigenous Rights.

Previous studies on consumer perceptions and behaviors of salmon have often neglected Indigenous rights within the Canadian salmon sector. This study innovatively addresses this gap by integrating Indigenous rights into the current analysis, alongside considerations of sustainability practices, socio-economic impacts, and consumer motivations. Our research objectives aim to fit three consumer perceptions-environmental sustainability, economic considerations, and Indigenous rights-and to evaluate their associations, alongside perception of a price increase, socio-demographics, and consumer motivation factors, with purchasing behaviors related to Canadian salmon products. Data for this study was collected from a nationwide online survey. Responses to Question 2 and Question 35 are encoded with numerical values ranging from 1 to 5, where larger numbers indicate stronger agreement with the statement. The inclusion of methodologies such as the Graded Response Model (GRM) and Cumulative Link Models (CLM) adds another innovative dimension to this study. Our findings demonstrate how consumer profiles are associated with these four perceptions and their underlying determinants. Furthermore, the study quantifies the influence of these four perceptions on each consumer purchase behavior. The implications of these findings extend to the realm of mathematical modeling in consumer decision-making processes, offering practical insights for businesses and marketers, and emphasizing the importance of implementing regulatory frameworks and initiatives that promote sustainability, safeguard Indigenous rights, and address socio-economic disparities.

Influence of temperature on the behaviour and physiology of Atlantic salmon (Salmo Salar) on a commercial farm

Commercial Atlantic salmon (Salmo salar) farms face challenges under climate change, as rising sea temperatures and higher variability in weather patterns can lead to thermal stress events, compromising fish health, and resulting in lower production efficiency. Temperature plays a critical role in influencing the physiological and behavioural response of salmon under stressful conditions and effective farm management requires a nuanced comprehension of its function to adjust farming practices and minimize further stress. Two types of biologgers, measuring external acceleration, depth, heart rate, and temperature were surgically implanted for 245 days to explore the effects of the thermal response of Atlantic salmon during a standard production cycle. Apparent heart rate scope and Arrhenius breakpoint temperature were used to estimate the optimal temperature and both methods resulted in an estimate of 12.7 °C. There was a reduction in apparent heart rate scope at temperatures below 2 °C and >19 °C suggesting proximity to limits of thermal stress. The use of biologgers facilitates direct observations in commercial operations, providing essential information for aquaculture management. These findings contribute to a holistic understanding of the effect of temperature influencing Atlantic salmon physiology and behaviour on aquaculture farms, bridging the gap between controlled laboratory studies and real-world commercial operations.

Comparing the migration behavior and survival of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) smolts.

Many organisms rely on migrations between habitats to maximize lifetime fitness, but these migrations can be risky due to a suite of factors. In anadromous salmonids, the smolt migration from fresh water to sea is a critical life stage, during which smolts can experience high mortality from multiple sources. This study investigated the migratory behavior and survival of Atlantic salmon (Salmo salar) and anadromous brown trout (Salmo trutta) smolts during their seaward migration using acoustic telemetry between March and May 2021. Due to the extinction of wild salmon in the River Gudenaa after the construction of the Tange hydropower plant, this study used hatchery-reared salmon originating from a nearby Danish river. A total of 75 hatchery-reared salmon smolts, 75 hatchery-reared trout smolts, and 75 wild trout smolts were tagged with acoustic transmitters and released into River Gudenaa, Denmark. The downstream movements of tagged fish were monitored using acoustic receivers deployed in the river and fjord. Hatchery-reared trout initiated migration first, followed by hatchery-reared salmon, with wild trout being the last to migrate. There was no difference in riverine progression rates among the three smolt groups, but noticeable differences emerged once in the fjord: trout (wild and hatchery) slowed down, whereas hatchery-reared salmon maintained their speed. Riverine migration was predominantly nocturnal for all smolts; however, daytime migration increased at the fjord arrays. Day-of-year significantly influenced diurnal patterns in the river and fjord, where daytime migration increased later in the year. Hatchery-reared salmon and wild trout had reasonably good overall survival from river to sea entry (≥66%), whereas hatchery-reared trout had poor survival (c.26%). The fjord was the major bottleneck for survival of hatchery-reared trout. We found no strong evidence for differences in progression rate or diurnal patterns between wild and hatchery-reared trout to explain the lower survival. This study demonstrates that salmon and trout differ in their life-history strategy already in the post-smolt phase, and that stocking is a sub-optimal strategy to aid wild populations.

Assessment of activity and heart rate as indicators for acute stress in Atlantic salmon

The aim of this study was to assess whether activity and heart rate sensor implants can be used to measure stress and thus estimate one important welfare indicator for fish in aquaculture pens, and if such measurements correlate to physiological factors measured through blood sampling. The experiment consisted of two parts: i) a bio-logger study where implanted sensors were used to monitor activity and heart rates for fish undergoing stress (crowding); and ii) an analysis of blood constituents (cortisol, glucose, lactate, and chloride) of a second group of fish undergoing the same treatment. We found that activity measurements can be used to track high-impact stress events but may not be suitable to discern possibly nuanced reactions to stress impacts of lower magnitude. While heart rate was measured reliably, e.g., in showing clear circadian rhythms, it was no credible proxy for predicting stress in this study. Our results thus underline challenges observed in previous work around the use of heart rate as stress indicator, and imply that the translation of its meaning into a proxy for stress needs further work. Although tag-based monitoring of stress is not without its difficulties, studies such as this provide a wealth of information on salmon behaviour and physiology, and the links between these.

Premises for a digital twin of the Atlantic salmon in its world: Agency, robustness, subjectivity and prediction

AbstractAquaculture of Atlantic salmon Salmo salar is in transition to precision fish farming and digitalization. As it is easier, cheaper and safer to study a digital replica than the system itself, a model of the fish can potentially improve monitoring and prediction of facilities and operations and replace live fish in many what‐if experiments. Regulators, consumers and voters also want insight into how it is like to be a salmon in aquaculture. However, such information is credible only if natural physiology and behaviour of the living fish is adequately represented. To be able to predict salmon behaviour in unfamiliar, confusing and stressful situations, the modeller must aim for a sufficiently realistic behavioural model based on the animal's proximate robustness mechanisms. We review the knowledge status and algorithms for how evolution has formed fish to control decisions and set priorities for behaviour and ontogeny. Teleost body control is through genes, hormones, nerves, muscles, sensing, cognition and behaviour, the latter being agentic, predictive and subjective, also in a man‐made environment. These are the challenges when constructing the digital salmon. This perspective is also useful for modelling other domesticated and wild animals in Anthropocene environments.

How much light intensity to induce repulsion or attraction behaviour in juvenile salmon?

How much light intensity to induce repulsion or attraction behaviour in juvenile salmon?

Physiological condition infers habitat choice in juvenile sockeye salmon.

The amount of time that juvenile salmon remain in an estuary varies among and within populations, with some individuals passing through their estuary in hours while others remain in the estuary for several months. Underlying differences in individual physiological condition, such as body size, stored energy and osmoregulatory function, could drive individual variation in the selection of estuary habitat. Here we investigated the role of variation in physiological condition on the selection of estuarine and ocean habitat by sockeye salmon (Oncorhynchus nerka) smolts intercepted at the initiation of their 650-km downstream migration from Chilko Lake, Fraser River, British Columbia (BC). Behavioural salinity preference experiments were conducted on unfed smolts held in fresh water at three time intervals during their downstream migration period, representing the stage of migration at lake-exit, and the expected timing for estuary-entry and ocean-entry (0, 1 and 3 weeks after lake-exit, respectively). In general, salinity preference behaviour varied across the three time periods consistent with expected transition from river to estuary to ocean. Further, individual physiological condition did influence habitat choice. Smolt condition factor (K) and energy density were positively correlated with salinity preference behaviour in the estuary and ocean outmigration stages, but not at lake-exit. Our results suggest that smolt physiological condition upon reaching the estuary could influence migratory behaviour and habitat selection. This provides evidence on the temporally dependent interplay of physiology, behaviour and migration in wild juvenile Pacific salmon, with juvenile rearing conditions influencing smolt energetic status, which in turn influences habitat choice during downstream migration. The implication for the conservation of migratory species is that the relative importance of stopover habitats may vary as a function of initial condition.

Mouth Opening Frequency of Salmon from Underwater Video Exploiting Computer Vision

Maintaining fish welfare is one of the most prevailing and challenging tasks in aquaculture production, in particular as there can be more than 200,000 fish present within a single sea cage. Observing this amount of individual animals is a very challenging task and requires a high degree of automated computer vision-based monitoring along with the use of advanced machine learning and AI algorithms. This paper introduces a computer vision based approach for determining the ventilation frequency in terms of the mouth opening frequency of salmon in aquaculture environments through underwater video analysis. We exploit an object detection network to detect specific salmon features including head, eye, snout, mouth and then apply optical flow analysis to the snout region to assess their ventilation rates, serving as a potential indicator of fish health and well-being. This aims towards analyzing salmon behavior on individual level in real-time, enabling an in-depth view of the population's status. Our methodology represents a significant progress towards a more automated salmon monitoring providing an objective measure to determine an important aspect offish behaviour in an effective way which will subsequently help to enhance efficiency in aquaculture operations. The results, obtained from analyzing annotated videos are very promising and validate the usability of our approach. This study also paves the way for further exploration into utilizing computer vision and machine learning for comprehensive fish status assessment, contributing valuable insights into sustainable aquaculture practices.

Tidal gradients, fine-scale homing and a potential cryptic ecotype of wild spawning pink salmon (Oncorhynchus gorbuscha).

The homing behaviour of salmon is a remarkable natural phenomenon, critical for shaping the ecology and evolution of populations yet the spatial scale at which it occurs is poorly understood. This study investigated the spatial scale and mechanisms driving homing as depicted by spawning site-choice behaviour in pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Molecular pedigree analyses of over 30,000 adult spawners in four streams revealed that pink salmon exhibit fine-scale site fidelity within a stream, returning to within <100 m of their parents. Homing behaviours were driven in part by a salinity gradient between intertidal and freshwater environments, with individuals incubated in freshwater environments more than twice as likely to spawn upstream of tidal influence than those incubated in the intertidal. Our findings challenge the traditional view that pink salmon populations are genetically and phenotypically homogenous due to their short freshwater residency as juveniles and high rates of dispersal as returning adults (i.e. straying). This study has important implications for rates of inbreeding, local adaptation and gene flow within populations, and is particularly relevant to the management of salmon hatcheries, given the high incidence of hatchery-origin pink salmon, reared in freshwater hatchery environments, that stray into wild populations of Prince William Sound.

Behavioral responses of Chinook salmon to shipping noise in Cowichan Bay, British Columbia

The increase in human-generated noise over the last 60 years has led to concerns regarding the impacts of shipping noise on marine species. Two important species in the northeast Pacific are declining, southern resident killer whales and their main prey, Chinook salmon. We know that killer whales change their behavior in the presence of ships, but no work has been done on salmon. Acoustic receivers and underwater hydrophones were deployed in Cowichan Bay, British Columbia, Canada, to understand potential changes in behavior as salmon encounter shipping noise. Depth and acceleration of adult Chinook salmon were monitored using acoustic tags and were modeled against environmental conditions (e.g., currents) to understand general movement and behavior. Underwater sound pressure levels were then added to the model to assess potential responses to ship noise. Over 3 years, 53 Chinook salmon were tagged, resulting in 167,628 individual detections. Detections revealed spatial and temporal patterns in habitat use and behavior prior to river entry and provided the first data on Chinook salmon responses to anthropogenic noise. These data provide novel insights into the behavior of adult Chinook salmon and crucial information on the impacts of anthropogenic noise on this key species.

Qualitative Behavioural Assessment as a welfare indicator for farmed Atlantic salmon (Salmo salar) in response to a stressful challenge.

Animal welfare assessments have struggled to investigate the emotional states of animals while focusing solely on available empirical evidence. Qualitative Behavioural Assessment (QBA) may provide insights into an animal's subjective experiences without compromising scientific rigor. Rather than assessing explicit, physical behaviours (i.e., what animals are doing, such as swimming or feeding), QBA describes and quantifies the overall expressive manner in which animals execute those behaviours (i.e., how relaxed or agitated they appear). While QBA has been successfully applied to scientific welfare assessments in a variety of species, its application within aquaculture remains largely unexplored. This study aimed to assess QBA's effectiveness in capturing changes in the emotional behaviour of Atlantic salmon following exposure to a stressful challenge. Nine tanks of juvenile Atlantic salmon were video-recorded every morning for 15 min over a 7-day period, in the middle of which a stressful challenge (intrusive sampling) was conducted on the salmon. The resultant 1-min, 63 video clips were then semi-randomised to avoid predictability and treatment bias for QBA scorers. Twelve salmon-industry professionals generated a list of 16 qualitative descriptors (e.g., relaxed, agitated, stressed) after viewing unrelated video-recordings depicting varying expressive characteristics of salmon in different contexts. A different group of 5 observers, with varied experience of salmon farming, subsequently scored the 16 descriptors for each clip using a Visual Analogue Scale (VAS). Principal Components Analysis (correlation matrix, no rotation) was used to identify perceived patterns of expressive characteristics across the video-clips, which revealed 4 dimensions explaining 74.5% of the variation between clips. PC1, ranging from 'relaxed/content/positive active' to 'unsettled/stressed/spooked/skittish' explained the highest percentage of variation (37%). QBA scores for video-clips on PC1, PC2, and PC4 achieved good inter- and intra-observer reliability. Linear Mixed Effects Models, controlled for observer variation in PC1 scores, showed a significant difference between PC1 scores before and after sampling (p = 0.03), with salmon being perceived as more stressed afterwards. PC1 scores also correlated positively with darting behaviours (r = 0.42, p < 0.001). These results are the first to report QBA's sensitivity to changes in expressive characteristics of salmon following a putatively stressful challenge, demonstrating QBA's potential as a welfare indicator within aquaculture.

Response of Atlantic salmon in flexible sea cages to waves and currents: Measurements at farm-level and modeling

The shift towards salmon farming in more exposed locations has been an industry-wide trend for the last decade. Moving fish farms to locations with high water currents and waves can improve production by providing more stable temperatures and water quality, as well as reducing the negative environmental impacts of fish farming. This study investigates how waves affect the behavior of salmon from the same group, reared at different locations within a fish farm in standard circular sea cages. Using echosounders, DO (dissolved oxygen), temperature sensors and ADCP (Acoustic Doppler Current Profiler), we show that salmon avoid waves, swim below them and maintain their normal behavior. We also show that salmon behavior is related to the exposure of the cage, in the farm layout, to waves and currents. An integrated numerical model of fish and flexible sea cages is used to simulate the fish behavior under waves and currents and it able to reproduce the observed fish distributions in general.

Imaging‐sonar observations of salmonid interactions with a vertical axis instream turbine

AbstractAnthropogenic activities and their influences on aquatic systems is an important topic, especially considering the growing interest in using the earth's resources in a sustainable way. One of those anthropogenic activities is the introduction of renewable technologies into the aquatic environment such as instream turbines. Environmental studies around those technologies are often still ongoing due to their novelty. During the spring of 2018, juvenile individuals of two salmonid species, Atlantic salmon and brown trout were released upstream a vertical axis instream turbine in the river Dal (Dalälven) in eastern Sweden. The aim of this study was to investigate the swimming behavior of the salmonids around a small‐scale prototype vertical axis instream turbine. The swimming pattern and the possible response of avoiding the vertical axis instream turbine were documented with a multi beam sonar. A control area, next to the turbine, was used as reference. No consistent results were shown for trout as they were passing the control area with a statistically high variation, and specimens were rarely observed in proximity of the turbine, neither if the turbine was operating nor at stand still. Salmon clearly avoided the operating turbine, but did not avoid the turbine when it was at stand still, and was often observed swimming straight through the turbine area. These findings indicate that operating this type of instream turbine in a river affects the swimming behavior of Atlantic salmon but is unlikely to affect its migration paths. For brown trout, the statistical results are inconclusive, although data indicate a response of avoiding the turbine. The species are in little risk to suffer physical harm as no fish entered the rotating turbine, despite very turbid water conditions.

Smallmouth bass (Micropterus dolomieu) suppress Atlantic salmon (Salmo salar) feeding activity and increase aggressive behaviours at warmer temperatures

AbstractBy 2050, mean temperature in the state of Maine, located in the Northeastern USA, is expected to increase nearly 1°C, which could directly affect native coldwater salmonid behaviour and increase competition with warmwater smallmouth bass. We conducted a microcosm experiment to examine the feeding and agonistic behaviour of endangered juvenile Atlantic Salmon (Salmo salar) at two temperatures (18 and 21°C) in the presence and absence of non‐native Smallmouth Bass (Micropterus dolomieu). By visually reviewing footage of fish competition in our tanks, we quantified feeding and agonistic interactions. We predicted salmon would exhibit lower feeding activity than bass at 21°C and antagonistic interactions between the two species would increase with warming. We found salmon feeding activity was reduced by smallmouth bass presence and this effect was stronger at 21°C. We also found smallmouth bass aggression was strongest at 21°C when salmon were present. Lastly, feeding activity and aggression in both species changed with food availability. These findings illustrate the potential for invasive warmwater species to outcompete native salmonids for resources, especially under the warmer conditions predicted by climate change scenarios.