Atlantic Salmon Salmo Salar Parr Research Articles

Common-garden comparison of relative survival and fitness-related traits of wild, farm, and hybrid Atlantic salmon Salmo salar parr in nature

When escapee farmed Atlantic salmon Salmo salar interbreed with wild fish, the introgression of maladaptive genes can lower wild population productivity and alter key life history traits. To date, only a few European studies have compared wild, farm, and hybrid salmon under common conditions in the wild, isolating the influence of genetics on survival and fitness-related traits. Here, we examined the performance of experimentally derived Atlantic salmon fry from 4 cross types (wild, farm, and reciprocal F1 hybrids) during the first summer of growth at 3 locations in southern Newfoundland. Overall survival was high, with the cross type rank order consistent across sites (mean percent recaptured: wild-mother hybrids 26.2% ≈ wild 26.0% > farm 19.2% > farm-mother hybrids 12.8%). Wild fish were smaller than wild-mother hybrids and farm fish, though differed less in size from farm-mother hybrids. At 2 out of 3 sites, wild-mother hybrids were larger than wild and farm-mother hybrid fish but had only a small size advantage over farm fish. Shape differences were small and mainly related to body depth, with the largest differences between wild and farm fish. Wild-mother hybrids had fewer parr marks than other cross types at a single site, and though differences in the size of marks were minimal, farm fish tended to have the narrowest marks. Overall, these results show that genetic differences exist for fitness-related traits among wild, farm, and hybrid juveniles, even over short temporal scales and under favourable environmental conditions, and may contribute to patterns of reduced farm-mother hybrid and feral farm survival in the wild.

TỔNG QUAN VỀ VIỆC SỬ DỤNG SELEN (Se) TRONG NUÔI TRỒNG THỦY SẢN

Effects of antibiotics usage in aquaculture on environment and human health has prompted the search for alternative products. Recently, the microelements in organic form have been used as alternative to antibiotics in aquaculture. Se is one of the microelements that have received heightened attention. This report reviews the role of Se in the culture of fishes (cobia Rachycentron canadum L., red sea bream Pagrus major, fingerling channel catfish Ictalurus punctatus, seabass Lates calcarifer, snubnose dart Trachinotus blochii, rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio L., Atlantic salmon parr Salmo salar, nile tilapia Oreochromis niloticus, african catfish Clarias gariepinus, Senegalese sole Solea senegalensis, grouper Epinephelus malabaricus, gilthead seabream Sparus aurata, Chinook salmon Oncorhynchus tshawytscha, fathead minnow Pimephales promelas, striped bass Morone saxatilis, bluegill Lepomis macrochirus, crucian carp Carassius auratus gibelio) and crustacean (giant freshwater prawn Macrobrachium rosenbergii, white shrimp Penaeus vannamei, marron Cherax cainii, crayfish Procambarus clarkii). Suggestion for further research on the application of Se in aquaculture is also included.

A three-phase excess post-exercise oxygen consumption in Atlantic salmon Salmo salar and its response to exercise training.

The recovery of oxygen uptake to the standard metabolic rate (SMR) following exhaustive chasing exercise in Atlantic salmon Salmo salar parr occurred in three phases (rapid, plateau and slow). The initial recovery phase lasted 0·7 h and contributed 16% to the total excess post-exercise oxygen consumption (EPOC). It was followed by a longer plateau phase that contributed 53% to the total EPOC. The slow recovery phase that completed recovery of SMR, which has not been reported previously, made a 31% contribution to the total EPOC. The plasticity of EPOC was demonstrated in exercise-trained fish. Exercise training increased EPOC by 39% when compared with control fish (mean ± S.E., 877·7 ± 73·1 v. 629·2 ± 53·4 mg O2 kg-1 , d.f. = 9, P <0·05), with the duration of the plateau phase increasing by 38% (4·7 ± 0·58 v. 3·4 ± 0·16 h, d.f. = 9, P <0·05) and the contribution of the slow phase to the total EPOC increasing by 80% (173·9 ± 23·9 v. 312·5 ± 50·4 mg O2 kg-1 , d.f. = 9, P< 0·05). As a result, the combination of the plateau and slow phases of exercise-trained fish increased by 47% compared with control fish (756·6 ± 71·4 v. 513·6 ± 43·1 mg O2 kg-1 ; d.f. = 9, P= 0·01). To substantiate the hypothesis that the plateau and slow recovery phase of EPOC was related to general metabolic recovery following exhaustive exercise, the time-course for recovery of SMR was compared with previously published metabolite recovery profiles. The final phase of metabolic recovery was temporally associated with the final phases of gluconeogenesis, lactate oxidation and muscle intracellular pH regulation. Therefore, the plasticity of the latter phase of EPOC agreed with the known effects of exercise training in fishes.

Plasticity in response to feed availability: Does feeding regime influence the relative growth performance of domesticated, wild and hybrid Atlantic salmon Salmo salar parr?

Growth of farmed, wild and F1 hybrid Atlantic salmon parr Salmo salar was investigated under three contrasting feeding regimes in order to understand how varying levels of food availability affects relative growth. Treatments consisted of standard hatchery feeding (ad libitum), access to feed for 4 h every day, and access to feed for 24 h on three alternate days weekly. Mortality was low in all treatments, and food availability had no effect on survival of all groups. The offspring of farmed S. salar significantly outgrew the wild S. salar, while hybrids displayed intermediate growth. Furthermore, the relative growth differences between the farmed and wild S. salar did not change across feeding treatments, indicating a similar plasticity in response to feed availability. Although undertaken in a hatchery setting, these results suggest that food availability may not be the sole driver behind the observed reduced growth differences found between farmed and wild fishes under natural conditions.

Effects of environmental fluctuations on fish metabolism: Atlantic salmon Salmo salar as a case study.

Using Atlantic salmon Salmo salar parr as study species, recent findings are summarized on how (1) diurnal variations in water temperature affects standard metabolic rate, (2) shelter may reduce routine metabolic rate and (3) fluctuations of water speed affect the costs of activity. The results suggest that the accuracy of bioenergetics models can be hampered if the effects of environmental fluctuations are omitted. Incorporating environmental fluctuations into estimates and models of fish metabolism will not only improve the accuracy of energy budget calculations, but also have crucial management implications for conservation and improve the capacity to predict effects of climate change.

Bioelectrical Impedance Analysis to Estimate Lipid Content in Atlantic Salmon Parr as Influenced by Temperature, PIT Tags, and Instrument Precision and Application in Field Studies

AbstractThe objective of this study was to investigate the effectiveness of bioelectrical impedance analysis (BIA) in field studies monitoring Atlantic Salmon Salmo salar parr, as related to temperature corrections, instrument precision, and passive integrated transponder (PIT) tags. Currently, BIA studies are restricted to laboratory settings where water temperature is controlled to decrease error in BIA predictions caused by fish body temperature. We compared models of predicted total and percent lipids with and without temperature corrections and found that temperature corrections reduced error caused by temperature. Without temperature corrections, an 8°C increase in temperature increased the predicted total lipids by 55%. After temperature corrections were added, the predicted total lipid only increased by 2.55%. Repeated measurements were collected on 40 salmon parr (56–115 mm FL) in four separate time trials (1 min, 1.5 h, 3 h, and 6 h), and we found that lipid content predictions between measurements were not significantly different; however, the variability within longer time trials was moderate (6.43% error). No significant differences were found in the predicted lipid value before or after PIT tags were removed from the body cavity, suggesting PIT tags do not affect BIA readings. On average, the difference between predicted total lipids after tag removal was 0.0023 and 0.02 g for 12.5‐mm and 22‐mm PIT tags, respectively. We also observed that increases in fish body temperature caused by handing resulted in increased variability in BIA estimates, indicating the need for temperature corrections.Received March 10, 2014; accepted September 22, 2014

Individual variability of wild juvenile Atlantic salmon activity patterns: effect of flow stage, temperature, and habitat use

The magnitude of variation of diel activity patterns and habitat use of wild Atlantic salmon (Salmo salar) parr was examined during the summer and autumn through a gradient of declining temperature. Fish were marked with passive integrated transponders and tracked using a large network of flatbed antennas. High interindividual variability was observed, as some individuals were predominantly nocturnal whereas others frequently changed their daily activity pattern. Overall fish activity decreased with decreasing temperature and increasing flow stage, but most of these changes in daily activity were observed in crepuscular periods. Parr used habitats with lower velocity at night than in the day during the summer, but not in the autumn. Furthermore, there was no difference between day and night habitats for fish that were cathemeral (active both day and night during a given day), so differences between day and night habitats were the result of individuals adopting different activity patterns. These results suggest that habitat interacts with activity pattern, as individuals using suboptimal habitats seem to increase daytime foraging to secure sufficient energy. Temporal and among-fish variability of activity patterns illustrate the dynamic nature of foraging decisions that may partly result from trade-offs experienced at the microhabitat scale.

Passive Integrated Transponder (PIT) Tracking versus Snorkeling: Quantification of Fright Bias and Comparison of Techniques in Habitat Use Studies

AbstractQuantitative assessment of day and night fright bias (i.e., flight response) of Atlantic Salmon Salmo salar parr during passive integrated transponder (PIT) tracking surveys was carried out during summer (water temperature, 18–22°C) and autumn (water temperature, &lt;3°C). In addition, PIT‐tracking and snorkeling survey methods were compared to assess whether the two methods result in similar habitat use data for Atlantic Salmon parr at the same study site. During summer fright bias surveys, 0–15% of parr displayed a flight response to PIT‐tracking techniques in the riffle–run–pool habitat types commonly used by Atlantic Salmon parr; 24–25% displayed a flight response in relatively unused, shallow, calm water habitats. No flight responses were observed in autumn surveys with colder water temperatures in any habitat type. Larger numbers of salmon parr were observed using PIT tracking regardless of stream discharge. Furthermore, significant differences in habitat use frequency curves between these two methods were observed due largely to higher Atlantic Salmon parr abundances being detected by PIT tracking in shallow water depths at lower discharges and the ability to detect inactive salmon parr hiding within the substrate. PIT tracking was found to be a valid method for habitat assessment and provides more reliable habitat use data than traditional snorkeling methods in small streams.

Morphological variability of Atlantic salmon Salmo salar and brown trout Salmo trutta in different river environments

Abstract – The morphologies of sympatric juvenile Atlantic salmon Salmo salar parr and brown trout Salmo trutta parr were compared between Irish rivers with contrasting hydraulic environments – a high‐gradient and a low‐gradient tributary from the River Barrow catchment, south‐east Ireland and a high‐gradient river from the Burrishoole catchment, west of Ireland. The two catchments differ markedly in mean annual precipitation (849.0 mm year−1 and 1370.3 mm year−1 for the Barrow and Burrishoole catchments, respectively). Parr of both species demonstrated morphological variation between and within catchments. Changes in metrics such as pectoral fin length, body depth and body length between and within catchments suggest that hydraulic forces were a major determinant of morphological variation. Both species from the Burrishoole catchment had relatively larger pectoral fins, longer heads, larger eyes and shallower bodies than conspecifics from the Barrow catchment. In rivers subject to frequent rainfall‐driven high discharges, such as those in the Burrishoole catchment, a more fusiform body and head shape coupled with larger pectoral fins may reduce the energetic cost of maintaining position in the water column, as well as increase stability and manoeuvrability. The larger eyes in both parr species in the Burrishoole catchment could further be a response to the lower visibility of the more turbid and peat‐stained waters or to the reduced prey availability. The results of this study demonstrate that local adaptation to flow conditions can yield morphologically distinct populations and that multiple species can exhibit parallel phenotypic responses to changing environmental conditions.

Interactions between riparian shading and food supply: a seasonal comparison of effects on time budgets, space use and growth in Atlantic salmon Salmo salar

This study examines seasonal (winter v. summer) differences in space-time budgets, food intake and growth of Atlantic salmon Salmo salar parr in a controlled, large-scale stream environment, to examine the direction and magnitude of shifts in behaviour patterns as influenced by the availability of overhead cover and food supply. Salmo salar parr tested in the presence of overhead cover were significantly more nocturnal and occupied more peripheral positions than those tested in the absence of overhead cover. This increase in nocturnal activity was driven primarily by increased activity at night, accompanied by a reduction in daytime activity during winter. The presence of overhead cover had no effect on rates of food intake or growth for a given food supply in a given season. Growth rates were significantly higher for fish subjected to a high food supply than those subjected to a low food supply. Food supply did not affect the extent to which S. salar parr were nocturnal. These results were consistent between winter and summer. The use of riparian shading as a management technique to mitigate the effects of warming allows the adoption of more risk-averse foraging behaviour and may be particularly beneficial in circumstances where it serves also to increase the availability of food.

Habitat Choice by Atlantic Salmon Parr in Relation to Turbulence at a Reach Scale

AbstractThe variables commonly used to describe the physical habitat of Atlantic salmon Salmo salar parr are average velocity, water depth, and substrate. A variety of micro‐ and mesohabitat models have been developed using these variables to assess habitat quality. However, Atlantic salmon parr live in highly turbulent streams and rivers in which intense fluctuations of water velocity occur. Laboratory experiments have shown that turbulence affects the behavior and energetics of fish. Nevertheless, habitat use in relation to the strong temporal variability of velocity in natural environments has rarely been studied. In this study, Atlantic salmon parr habitat was examined in relation to turbulence in the Patapédia River, Quebec. Rather than taking the usual approach of surveying a large population at one point in time, we used an intensive radiotelemetry tracking survey that focused on the habitat use of a few individual fish over an extended period. We analyzed habitat use in relation to several dynamic hydraulic variables. Our results revealed that under naturally turbulent conditions, the parr displayed high individual variability in their habitat use. Such heterogeneous use of habitat suggests that individuals are not constrained to a single habitat type. Furthermore, no differences were observed in habitat use among the four daily periods (dawn, day, dusk, and night) for individual parr.

Habitat use of Atlantic salmon Salmo salar parr in a dynamic winter environment: the influence of anchor‐ice dams

The effect of anchor‐ice dams on the physical habitat and behavioural responses of Atlantic salmon Salmo salar parr in a small, steep stream was investigated. Anchor‐ice dams formed periodically, leading to a dynamic winter environment as the study reach alternated between riffle and walk dominated habitat. Parr demonstrated large individual variation in habitat use, utilizing most of the wetted stream width, and were generally unaffected by diel changes in the mesohabitat composition. Furthermore, parr displayed high site fidelity in areas with low embedded substrata, and demonstrated few large movements between the three mesohabitat classes present: shallow riffle, walk and pool. Findings from this study question the importance of hydraulic variables such as water depth, flow velocity and dynamic ice formation as single habitat features for juvenile stream salmonids during winter and emphasize the importance of access to substratum cover.

Food consumption and growth of Atlantic salmonSalmo salarparr in sub‐Arctic rivers: empirical support for food limitation and competition

The quantitative food consumption and somatic growth of Atlantic salmonSalmo salarparr were compared between three sub‐Arctic rivers in northern Norway and Finland, addressing the potential occurrence of resource limitation and interspecific competition. In one of the rivers, previous resource partitioning studies have suggested severe dietary competition between juvenileS. salarand a dense population of alpine bullheadsCottus poecilopus. It was hypothesized thatS. salarparr in this river would have restricted food consumption and growth rates compared to theS. salarpopulations in the other two rivers where interspecific competition was less likely to occur. The feeding and growth performance differed significantly between theS. salarpopulations. The lowest food acquisition and growth rates were in theS. salarparr population living in sympatry withC. poecilopus, confirming a restricted food supply for theS. salarparr and providing empirical support for the presence of resource limitation and interspecific food competition in this river system. The study reveals thatS. salarparr in sub‐Arctic rivers may experience food limitations resulting in diminished growth rates.

Stream Gradient‐Related Movement and Growth of Atlantic Salmon Parr during Winter

AbstractThere has been considerable focus on winter studies of Atlantic salmonSalmo salarparr during the last two decades. However, a lack of knowledge exists about the linkage between the physical conditions, including ice, and parr behavior in flow environments during the cold season. In this study, the movement and growth of Atlantic salmon parr were studied during winter in two stream sections with different gradients (0.3% and 1.8%) in a small natural river. Passive integrated transponder (PIT) technology was implemented by using both fixed antennae and mobile tracking devices. In the low‐gradient section, the formation of surface ice dominated and created stable conditions, whereas in the high‐gradient section, the formation of anchor ice and anchor ice dams occurred periodically and produced a dynamic environment. The results indicated a relationship between parr movement and river gradient. Movement by parr was negatively correlated with time from autumn to late winter but increased as spring approached. The level of movement was considered low (median = 0.9 m), but larger movements (up to 125.6 m) were recorded, indicating individual variation. Furthermore, parr inhabiting the low‐gradient section with the static ice formation exhibited larger movement than parr in the high‐gradient section with dynamic ice formation. Parr showed high site fidelity to both high‐ and low‐gradient sections but were less attracted to pool habitats. Finally, from late autumn to spring, parr demonstrated a specific growth rate close to 0.0%, indicating suitable conditions in both sections. As this study implies, the complexity of physical conditions during winter may lead to variability in individual fish response (i.e., movements). However, the results also imply that winter is not a limiting factor in parr performance if fish have access to suitable cover, such as areas with low substrate embeddedness.

Evidence for an autumn downstream migration and the subsequent estuarine residence of 0+ year juvenile Atlantic salmon Salmo salar L., in England

The use of passive integrated transponder technology facilitated the first observations of the autumn migration of 0+ year Atlantic salmon Salmo salar parr into tidal rearing habitats in the U.K. The quality of these habitats in relation to smolt production and the ecological significance of this alternative life‐history strategy are presently not understood.

Inter‐ and intra‐population morphological differences between wild and farmed Atlantic salmon juveniles

Whether population‐specific morphological differences were detectable in small (26–52 mm) Atlantic salmon Salmo salar parr reared under similar conditions was tested. Discrimination based on morphological characters was total (100%) between the fish of farmed origin (from AquaGen) and four wild fish populations. Between the four wild populations the corresponding discrimination was 59·8–86·3%. The inter‐population variation in morphological characters was larger than the intra‐population variation. The fish originating from the local populations at Driva and Innfjord were narrower in body form, whereas fish from the AquaGen and Innfjord populations had smaller and less pointed heads with smaller eyes. The Driva population fish had the smallest mouth while the longest pectoral fin was found in the Bjoreio population, the river that also has the largest fall gradient. Population‐specific morphological characters were thus detectable among Atlantic salmon parr relatively rapidly after yolk absorption.

Influence of Beaver Activity on Summer Growth and Condition of Age‐2 Atlantic Salmon Parr

AbstractThe activity of beavers Castor canadensis in freshwater environments can have considerable localized impacts on the physical and biological components of riparian ecosystems. By changing the habitat of a stream, beaver dams can cause spatial variation in growth opportunity that may have direct consequences for the growth of resident fish. In a small stream in eastern Canada, we studied the effects of an ephemeral beaver pond on the growth and maturity of age‐2 Atlantic salmon Salmo salar parr tagged with passive integrated transponder tags. Water temperature remained relatively uniform throughout the study site. We found very little movement of recaptured fish in the study site. Fish that were recaptured in the beaver pond displayed faster summer growth rates in both length and mass than fish that were recaptured immediately above or below the pond. We also found that parr in the pond maintained relatively high condition factors, whereas fish above and below the pond appeared to decrease in condition factor throughout the summer. In addition to growth, the maturation rates of age‐2 males were higher above the dam than below. This study demonstrates the effect a beaver dam can have on individual growth rates. By influencing growth during sensitive periods, the beaver pond may also influence individual life history pathways. This information could be an important component in ecosystem models that predict the effect of beaver population dynamics on the growth of individual salmonids at the landscape scale.

Chondroid bone and secondary cartilage contribute to apical dentary growth in juvenile Atlantic salmon

The microstructure and tissue composition of the dentary bone in Atlantic salmon salmo salar parr were examined using a variety of histological and whole‐mount techniques. Proximally, the dentary is composed of typical cellular lamellar bone with Sharpey's fibres extending dorsally, proximally and ventrally. Meckel's cartilage is located medially through the entire length of the dentary, and degrades distally resulting in a short transitional zone between hyaline cartilage and connective tissue. At the distal tip of the dentary, isogenic clusters of chondrocytes of periosteal origin were observed secreting small amounts of pericellular cartilage matrix within the bone matrix. These characteristics are highly indicative of secondary chondrogenesis, and suggest that the apical part of the dentary bone in Atlantic salmon does not grow via‘pure’ intramembranous ossification, but rather via a modified mode of periosteal ossification involving secondary cartilage and chondroid bone. Furthermore, the unusual mode of gender‐related dentary growth (kype formation) in adult male Atlantic salmon could be the continuation of a general mode of salmonid apical dentary growth.

Effects of food availability on temporal activity patterns and growth of Atlantic salmon

1. Patterns of sheltering and activity are of fundamental importance in the ecology of animals and in determining interactions among predators and prey. Balancing decreased mortality risk when sheltering with increased feeding rate when exposed is believed to be a key determinant of diel patterns of sheltering in many animals. 2. Despite lower foraging efficiency at night than during the day, Atlantic salmon Salmo salar parr are nocturnal during winter and at low summer temperatures. Nocturnal activity also occurs at warm water temperatures during summer, but little is known about the functional significance of this behaviour. 3. This study aimed to determine: (1) the preferred activity and shelter pattern of Atlantic salmon parr during warm summer months, and (2) their response to variations in food availability when balancing growth rate (G) and mortality risk (M), as expressed through time out of shelter. We differentiated among four potential responses to reduced food availability: (1) no response; (2) G decreases but M remains constant; (3) G remains constant but M increases; and (4) G decreases and M increases. 4. Time exposed from shelter was inversely related to food availability. Fish subject to high food availability were significantly less active during the day than those with restricted rations. However, food availability had no significant effect on the extent to which fish were active at night. There was no evidence of variation in growth rate with food availability. 5. Salmon were predominantly nocturnal at high ration levels, consistent with their previously reported behaviour during winter. Rather than switching to diurnal behaviour at high temperatures per se, as previously was supposed, it appears that the fish are diurnal only to the extent needed to sustain a growth rate, and this extent depends on food availability. 6. Atlantic salmon parr modulate the amount of time they are active rather than growth when responding to variations in food availability over an order of magnitude.

Diel and Seasonal Variation in Food Habits of Atlantic Salmon Parr in a Small Stream

ABSTRACT The diel and seasonal food habits of young-of-year (YOY) and post-young-of-year (PYOY) Atlantic salmon (Salmo salar) parr were assayed over the course of 11 months in the West Brook, Massachusetts USA. Gut fullness of YOY salmon did not vary significantly among months. PYOY salmon exhibited significant seasonal differences in gut fullness, with peak fullness occurring in the spring and late fall. Significant diel differences in PYOY gut fullness occurred in June and April, with peak fullness always occurring at dawn. Prey composition varied substantially among months. Dominant prey items of PYOY salmon were baetid mayflies in June, July, and August, limnephilid caddisflies in October and November, and ephemerellid mayflies in February and April. Few differences in prey composition between PYOY and YOY salmon were observed. Fish growth was unrelated to prey availability, but gut fullness explained up to 97% of growth variation across seasons. Results suggest that spring and fall are critical periods of feeding for PYOY salmon and that diel feeding intensity shifts seasonally.