Comparing the behavioural thermoregulation response to heat stress by Atlantic salmon parr (Salmo salar) in two rivers     

Emily Corey  Tommi Linnansaari  Stephen J. Dugdale  Normand Bergeron  Jean-François Gendron  Michel Lapointe  Richard A. Cunjak 《Ecology of Freshwater Fish》2020,29(1):50-62

Climate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon (Salmo salar) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature surpasses this threshold, juvenile salmon exploit thermal heterogeneity to behaviourally thermoregulate, forming aggregations in coolwater refuges. This study aimed to determine whether the behavioural thermoregulation response is universal across rivers, arising from common thermal cues. We detailed the temperature and discharge patterns of two geographically distinct rivers from 2010 to 2012 and compared these with aggregation onset temperature. PIT telemetry and snorkelling were used to confirm the presence of aggregations. Mean daily maximum temperature in 2010 was significantly greater in the OR versus the LSWM (p = 0.005), but not in other years (p = 0.090–0.353). Aggregations occurred on 14 and 9 occasions in the OR and LSWM respectively. Temperature at onset of aggregation was significantly greater in the OR (T_onset = 28.3°C) than in the LSWM (T_onset = 27.3°C; p = 0.049). Logistic regression models varied by river and were able to predict the probability of aggregation based on the preceding number of hours >23°C (R² = 0.61 & 0.65; P₅₀ = 27.4°C & 28.9°C; in the OR and LSWM respectively). These results imply the preceding local thermal regime may influence behaviour and indicate a degree of phenotypic plasticity, illustrating a need for localised management strategies.  相似文献   

Cohort‐specific variation in juvenile coho salmon habitat use          下载免费PDF全文

Catherine Bradley  Suresh Andrew Sethi  Joshua Ashline  Jonathon Gerken 《Ecology of Freshwater Fish》2017,26(4):695-706

In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics.  相似文献   

Seasonal growth and diet of juvenile chinook salmon (Oncorhynchus tshawytscha) in demonstration channels and the main channel of the Waitaki River, New Zealand, 1982–1983     

G. Power 《Ecology of Freshwater Fish》1992,1(1):12-25

Abstract– Juvenile chinook salmon in the Waitaki River, New Zealand and demonstration channels, living at about 16°C, increased in length by 0.32 mm day⁻¹ between 4 November and 4 March. They gained weight quickly, accumulated large visceral fat deposits and had high conditions factors. At 1600 h, stomachs averaged half full. The number of prey tended to decline as the fish grew and consumed larger items. Initially the diet was based mainly on chironomid larvae, but by December it included a diversity of prey in more equal proportions. These included Deleatidium in the Waitaki; amphipods in the demonstration channels; various trichopterans, hemipterans, elmid beetles, zooplankton. terrestrial dipterans and a variety of other prey. There were significant differences between sites in numbers of prey consumed and these probably reflected differences in the benthos. Diets in the Waitaki differ from those in the Rakaia River and the food of juvenile salmon appears closely linked to the availability of a diverse range of possible prey.  相似文献   

Importance of the River Teviot to Atlantic salmon, Salmo salar, rod catches in the River Tweed, Scotland     

M. HEDDELL-COWIE 《Fisheries Management and Ecology》2005,12(2):137-142

Abstract  The body mass distributions and variations in abundance of the spring and autumn catches of Atlantic salmon, Salmo salar L., were compared between fisheries above and below the confluence of the rivers Tweed and Teviot, Scotland. Significant differences between the distributions were found over three periods, one in spring and two in autumn, when salmon catches were high. Correlations were found between abundance trends for periods when distributions were similar or dissimilar. Abundance of salmon returning to the River Teviot was proportional to the main river. However, its population structure differed when abundances were high, suggesting different survival strategies. It appears that changes in the numbers returning to the river were resultant of changes in the marine rather than freshwater environment.  相似文献   

Ecological consequences of variation in standard metabolism and dominance among salmon parr     

John D. Armstrong  Karen J. Millidine  Neil B. Metcalfe 《Ecology of Freshwater Fish》2011,20(3):371-376

Abstract – Standard metabolic rate (SMR, closely related to basal and resting metabolism) varies by up to threefold among juvenile Atlantic salmon, Salmo salar L., of similar size at common temperature. Here, consequences of this variation are predicted by combining empirically derived relationships between SMR, specific dynamic action, energy budgets, water velocity, food level in the environment and food availability to fish. The range of velocities across which growth is predicted to occur is inversely related to a fish’s SMR. Growth is positively related to SMR at high but negatively related to it at low‐food levels. The relationship between food level and the range of velocities over which lower SMR fish can grow but higher SMR fish cannot is asymmetrically bi‐phasic and peaked. It is predicted that maternal manipulation of offspring SMR would generate fitness benefits through bet‐hedging against unpredictability in food level and increases in the overall range of velocities that the family of offspring can occupy and thrive in.  相似文献   

Determining spatial feed distribution in sea cage aquaculture using an aerial camera platform     

《Aquacultural Engineering》2019

Within this paper we describe an unmanned aerial vehicle (UAV) based method to estimate the spatial feed pellet distribution in salmon fish-cages and exploit it within a case study to determine the radial pellet distribution for different rotor spreaders and blower configurations. Compared to previously used methods, capturing pellets thrown from a rotary feed spreader in rows of Styrofoam boxes, the UAV based method is simpler and faster to setup and allows to cover a larger portion of the sea cage surface area. We compare results obtained with the Styrofoam box method with results we obtained by an automatic analysis of aerial videos taken by the UAV during feeding experiments. The employed method helps to gain insight into the spatial feed pellet distribution in full-scale salmon fish-cages where the feeding pipe and actual fixation of the spreader may influence the dynamic behaviour of the feeding system. This can also be seen as a step towards a continuous measuring of the feed pellet distribution, particularly in view of possible future feeding systems that may allow to adapt the feed pellet distribution to the actual fish distribution.  相似文献   

Some behavioural and ecological factors affecting distribution,biomass and production of juvenile Atlantic salmon          下载免费PDF全文

R. John Gibson 《Ecology of Freshwater Fish》2015,24(3):397-411

Observations were made in an experimental stream tank (total area 14.7 m²) on juvenile Atlantic salmon, Salmo salar L (parr), relating experimental observations to field observations, including the reported diurnal fasting behaviour of juvenile salmon at water temperatures <10 °C. Densities in the tank ranged from five to twenty parr, at water temperatures ranging from 4.6 °C to 15.8 °C. The wide channel of the stream tank, with mean water velocity of 18.8 cm·s^?1, was the preferred section, where territorial behaviour was observed. Biomass was regulated in the wide channel by territorial mosaics or by dominance hierarchies. Dominance hierarchies were reflected in coloration of the fish. Dominant salmon were generally in the wide channel. Densities of salmon parr (of mean fork length 10.2 cm) in the channel ranged from 0.84 m^?2 to 1.73 m^?2, with an average biomass of 14.2 g·m^?2. Growth was least at the 5.9 °C temperature treatment. In experiments at temperatures below 10 °C, feeding, dominance hierarchy and territorial behaviour were observed in daylight hours, contrary to the published literature. Interactions with other species may affect behaviour. Some observations were made on a closely related species, brown trout (Salmo trutta L.), a commonly cohabiting species in many systems. Trout displaced salmon from their preferred locations in the tank and were more aggressive than the salmon, reducing agonistic behaviour by the salmon. The commonest agonistic act shown by salmon was ‘charge’ and that by the trout was ‘approach’. Some field observations affecting behaviour and production are discussed.  相似文献   

Nutritional properties of dried salmon silage for broiler feeding          下载免费PDF全文

Nick Dale  Carolina Valenzuela 《Animal Science Journal》2016,87(6):791-795

The aim of this study was to evaluate the chemical composition, energy and amino acid profile of dried salmon silage (DSS) for broilers. The DSS was obtained by acid digestion of salmon mortalities and subsequently co‐dried with wheat bran in a 70:30 ratio (70 parts silage and 30 parts wheat bran). Samples of DSS were evaluated for chemical composition, gross energy, nitrogen‐corrected true metabolizable energy (TME_n), mineral content, total and digestible amino acids for broilers, and amino acid score. The chemical composition of DSS was (mean ± SD): moisture (12.3 ± 0.8%), crude protein (44.0 ± 1.1%), ether extract (5.0 ± 2.4%), crude fiber (3.3 ± 0.4%) and ash (9.4 ± 0.6%). The gross energy and TME_n for broilers were 4 069 kcal/kg and 2 613 kcal/kg, respectively. The DSS mineral composition showed a high content of calcium (1.01%) and phosphorus (1.08%). The DSS had high levels of digestible methionine (0.74%), lysine (2.27%), and threonine (1.16%), and did not present limiting amino acids for broilers. Nutritional composition of DSS showed high protein content with an amino acid profile considered to be suitable as a protein source for broiler feeding.  相似文献   

Main stem movement of Atlantic salmon parr in response to high river temperature          下载免费PDF全文

Stephen J. Dugdale  Jan Franssen  Emily Corey  Normand E. Bergeron  Michel Lapointe  Richard A. Cunjak 《Ecology of Freshwater Fish》2016,25(3):429-445

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature‐impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach‐scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.  相似文献   

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river     

Anton T. Ibbotson  William D. Riley  William R.C. Beaumont  Alastair C. Cook  Mark J. Ives  Adrian C. Pinder  Luke J. Scott 《Ecology of Freshwater Fish》2013,22(1):73-81

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.  相似文献