Growth Performance, Nutrient Digestibility, and Retention in Atlantic Salmon, L., Fed Diets with Fermented Sugar Kelp, .

Using low trophic marine resources such as sugar kelp () is of great interest to increase the circular food production in the ocean. Sugar kelp does, however, contain high levels of carbohydrates and iodine and does not have considerable levels of protein and lipids, which may make it less suitable as a feeding ingredient. A 10-week feeding trial was done to investigate the effect of graded dietary inclusion levels of fermented sugar kelp (FSK), on growth performance, digestibility, retention of nutrients, and mineral composition in postsmolt Atlantic salmon ( L.

Acute stress response on Atlantic salmon: a time-course study of the effects on plasma metabolites, mucus cortisol levels, and head kidney transcriptome profile.

Farmed Atlantic salmon (Salmo salar) welfare and performance can be strongly influenced by stress episodes caused by handling during farming practices. To better understand the changes occurring after an acute stress response, we exposed a group of Atlantic salmon parr to an acute stressor, which involved netting and transferring fish to several new holding tanks. We describe a time-course response to stress by sampling parr in groups before (T0) and 10, 20, 30, 45, 60, 120, 240, 300, and 330 min post-stress.

Increasing Dip Net Mesh Size Results in More Fin Splits in Post-Smolt Atlantic Salmon ().

Dip nets are widely used to retrieve fish from the water but can cause injuries to the fish. The objective of this study was to document the potential effects of dip net mesh size with respect to external injuries, more specifically fin splits and scale losses, in Atlantic salmon (). The study included 273 post-smolt Atlantic salmon from two fish batches referred to as the Tank group ( = 178 ± 36 g, = 198) and the Cage group ( = 1319 ± 334 g, = 75).

Warm water treatment increased mortality risk in salmon.

Thermal treatment is a controversial method to control sea lice in the Atlantic salmon farming industry. This study aimed to complement the growing evidence base to document the impact of thermal treatments on salmon welfare, behaviour, physiology and health. Here, fish were treated two times (four weeks apart) for 30 s in either 27, 30, or 33 °C warm water, and parameters were compared to a procedural control (exposed to their holding temperature of 14 °C) or a negative control (where no treatments were applied).

Molecular Mechanism Involved in Carotenoid Metabolism in Post-Smolt Atlantic Salmon: Astaxanthin Metabolism During Flesh Pigmentation and Its Antioxidant Properties.

A better understanding of carotenoid dynamics (transport, absorption, metabolism, and deposition) is essential to develop a better strategy to improve astaxanthin (Ax) retention in muscle of Atlantic salmon. To achieve that, a comparison of post-smolt salmon with (+ Ax) or without (- Ax) dietary Ax supplementation was established based on a transcriptomic approach targeting pyloric, hepatic, and muscular tissues. Results in post-smolts showed that the pyloric caeca transcriptome is more sensitive to dietary Ax supplementation compared to the other tissues.

Thermal injuries in Atlantic salmon in a pilot laboratory trial.

Thermal delousing is a new method for removing sea lice from farmed Atlantic salmon ( L). We investigated thermally-related tissue injuries in Atlantic salmon in a pilot laboratory trial to describe the acute effect of high water temperatures (34-38 °C). Acute tissue injuries in gills, eyes, brain and possible also nasal cavity and thymus were seen in salmon exposed to water temperatures of 34 - 38 °C in 72 to 140 s.

Sudden exposure to warm water causes instant behavioural responses indicative of nociception or pain in Atlantic salmon.

Thermal treatment has become the most used delousing method in salmonid aquaculture. However, concerns have been raised about it being painful for the fish. We studied the behavioural response of Atlantic salmon acclimated to 8 °C when transferred to temperatures in the range 0-38 °C.

Red and White Chinook Salmon (Oncorhynchus tshawytscha): Differences in the Transcriptome Profile of Muscle, Liver, and Pylorus.

Astaxanthin (Ax), the main carotenoid responsible for the distinct red flesh color in salmonids (Oncorhynchus, Salvelinus, Salmo, and Parahucho), is added to the diet of farmed fish at a substantial cost. Despite the great economical value for the salmon industry, the key molecular mechanisms involved in the regulation of muscle coloration are poorly understood. Chinook salmon (Oncorhynchus tshawytscha) represent an ideal model to study flesh coloration because they exhibit a distinct color polymorphism responsible for two color morphs, white and red flesh pigmented fish.

Mid and hindgut transcriptome profiling analysis of Atlantic salmon () under unpredictable chronic stress.

The intestinal epithelium is a selectively permeable barrier for nutrients, electrolytes and water, while maintaining effective protection against pathogens. Combinations of stressors throughout an animal's life, especially in agriculture and aquaculture settings, may affect the regular operativity of this organ with negative consequences for animal welfare. In the current study, we report the effects of a three-week unpredictable chronic stress (UCS) period on the intestinal morphology and transcriptome response of Atlantic salmon () parr midgut and hindgut.

Skeletal deformities in wild and farmed cleaner fish species used in Atlantic salmon Salmo salar aquaculture.

As a first attempt to assess bone health in cleaner fish production, wild and cultured ballan wrasse Labrus bergylta and lumpfish Cyclopterus lumpus were examined by radiology. In C. lumpus, wild fish (57%) had more vertebra deformities (≥1 deformed vertebrae) than cultured fish (2-16%).

CRISPR/Cas9-mediated editing of Δ5 and Δ6 desaturases impairs Δ8-desaturation and docosahexaenoic acid synthesis in Atlantic salmon (Salmo salar L.).

The in vivo functions of Atlantic salmon fatty acyl desaturases (fads2), Δ6fads2-a, Δ6fads2-b, Δ6fads2-c and Δ5fads2 in long chain polyunsaturated fatty acid (LC-PUFA) synthesis in salmon and fish in general remains to be elucidated. Here, we investigate in vivo functions and in vivo functional redundancy of salmon fads2 using two CRISPR-mediated partial knockout salmon, Δ6abc/5 with mutations in Δ6fads2-a, Δ6fads2-b, Δ6fads2-c and Δ5fads2, and Δ6bc with mutations in Δ6fads2-b and Δ6fads2-c. F0 fish displaying high degree of gene editing (50-100%) were fed low LC-PUFA and high LC-PUFA diets, the former containing reduced levels of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids but higher content of linoleic (18:2n-6) and alpha-linolenic (18:3n-3) acids, and the latter containing high levels of 20:5n-3 and 22:6n-3 but reduced compositions of 18:2n-6 and 18:3n-3.

Impact of Dietary Carbohydrate/Protein Ratio on Hepatic Metabolism in Land-Locked Atlantic Salmon ( L.).

A common-garden experiment was carried out to compare two genetically distinct strains of Atlantic salmon () fed diets with either high (CHO) or low (NoCHO) digestible carbohydrate (starch). Twenty salmon from either a commercial farmed strain (F) or a land-locked population (G) were placed in two tanks (10 fish of each population in each tank) and fed either CHO or NoCHO feeds. At the end of the experiment fish were fasted for 8 h, euthanized and blood and liver collected.

Uncontrollable chronic stress reduces growth disparities in farmed Atlantic salmon.

Individual variation in behavior and physiological traits in a wide variety of animals has been the focus of numerous studies in recent years. In this context, early life experiences shape responses that individuals have to subsequent environments, i.e.

Coping with a changing environment: the effects of early life stress.

Ongoing rapid domestication of Atlantic salmon implies that individuals are subjected to evolutionarily novel stressors encountered under conditions of artificial rearing, requiring new levels and directions of flexibility in physiological and behavioural coping mechanisms. Phenotypic plasticity to environmental changes is particularly evident at early life stages. We investigated the performance of salmon, previously subjected to an unpredictable chronic stress (UCS) treatment at an early age (10 month old parr), over several months and life stages.

A comparative study of the response to repeated chasing stress in Atlantic salmon (Salmo salar L.) parr and post-smolts.

When Atlantic salmon parr migrate from fresh water towards the sea, they undergo extensive morphological, neural, physiological and behavioural changes. Such changes have the potential to affect their responsiveness to various environmental factors that impose stress. In this study we compared the stress responses in parr and post-smolt salmon following exposure to repeated chasing stress (RCS) for three weeks.

Effect of predictability on the stress response to chasing in Atlantic salmon (Salmo salar L.) parr.

The possibility to prepare for and respond to challenges in a proper manner is essential to cope with a changing environment, and learning allows fish to up or downregulate the stress response based on experience. The regulation of the response to predicted needs should be easier in more predictable environments. We exposed salmon parr to chasing of either 15 s (weak stressor) or 5 min (strong stressor) twice daily for a 7-day learning period, with chasing either announced by a 30 s light signal (conditioned) or not announced (unconditioned).

Stress in Atlantic salmon: response to unpredictable chronic stress.

Combinations of stressors occur regularly throughout an animal's life, especially in agriculture and aquaculture settings. If an animal fails to acclimate to these stressors, stress becomes chronic, and a condition of allostatic overload arises with negative results for animal welfare. In the current study, we describe effects of exposing Atlantic salmon parr to an unpredictable chronic stressor (UCS) paradigm for 3 weeks.