Loss of Fshr Prevents Testicular Maturation in Atlantic Salmon (Salmo salar L.).

Early puberty poses a significant challenge for male Atlantic salmon in aquaculture due to its negative impact on growth and welfare. The regulation of puberty in vertebrates involves 2 key reproductive hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and their gonadal receptors. In male mice lacking FSH receptor, testes size is reduced, but fertility is maintained, while medaka and zebrafish with a disrupted fshr gene exhibit near normal testis size and fertility.

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.

The Distribution of IgT mRNA Cells in the Gut of the Atlantic Salmon ( L.).

The newly discovered IgT B cell is thought to play a dominant role in mucosal immunity, but limited studies have examined its distribution in fish species, hindering our understanding of its function. This study investigated IgT and poly Ig receptor (pIgR) mRNA cell distribution in Atlantic salmon () gut using RNAscope in situ hybridization (ISH) and assessed the effects of vaccination. The pyloric caeca, mid-intestine (first and second parts), and posterior segment in two weight stages (Group 1: avg.

Seasonal Changes in Photoperiod: Effects on Growth and Redox Signaling Patterns in Atlantic Salmon Postsmolts.

Farmed Atlantic salmon reared under natural seasonal changes in sea-cages had an elevated consumption of antioxidants during spring. It is, however, unclear if this response was caused by the increase in day length, temperature, or both. The present study examined redox processes in Atlantic salmon that were reared in indoor tanks at constant temperature (9 °C) under a simulated natural photoperiod.

Adaptive photoperiod interpretation modulates phenological timing in Atlantic salmon.

Photoperiod, the portion of 24-h cycle during which an organism is exposed to illumination, is an important phenological cue in many animals. However, despite its influence on critical biological processes, there remain many unknowns regarding how variations in light intensity translate into perceived photoperiod. This experiment examined how light intensity variations affect perceived photoperiod in Atlantic salmon (Salmo salar) to determine whether photoperiod interpretation is, a) fixed such that anything above a minimum detection threshold is regarded as 'illumination', or b) adaptive and varies with recent light exposure.

Autosomal Pseudogenes Explain Discordances Between Phenotypic Sex and DNA Marker for Sex Identification in Atlantic Salmon.

Despite the key role that sex-determination plays in evolutionary processes, it is still poorly understood in many species. In salmonids, which are among the best studied fishes, the master sex-determining gene sexually dimorphic on the Y-chromosome () has been identified. However, displays unexplained discordance to the phenotypic sex, with a variable frequency of phenotypic females being reported as genetic males.

Production and verification of the first Atlantic salmon (Salmo salar L.) clonal lines.

Background: In several fish species homozygous and heterozygous clonal lines have been produced using gynogenetic and androgenetic techniques. These lines are standardized and can be reproduced over generations. In rainbow trout such lines have existed for decades and has become important research tools in genome studies as well as in studies of commercially important traits.

Radiological changes during fracture and repair in neural and haemal spines of Atlantic cod (Gadus morhua).

Although spinal injuries in fish have been associated with electric stimuli applied during electrofishing and electrotrawling, bone fracture and repair in the axial skeleton have yet not been studied. To study this, we radiographed a group (n = 64) of individually tagged farmed cod twice, with a 1-year interval (∼36 cm at first and ∼ 50 cm at second inspection). The study focus was on the neural and haemal spines.

Sexual maturation and smoltification in domesticated Atlantic salmon (Salmo salar L.) - is there a developmental conflict?

We present data from two experiments that examined how the developmental processes of smoltification and sexual maturation proceed in parallel in domesticated Atlantic salmon. Onset of maturation and smoltification was stimulated using temperature and photoperiod. Our observations on gonadosomatic index (GSI), spermatogenic activity, gill Na+, K+-ATPase enzyme (NKA) activity, and plasma 11-ketotestosterone (11-KT), Na, Cl, and Ca show that smoltification and maturation were both triggered and developed in parallel in male Atlantic salmon, but that the progressing maturation impaired hypoosmoregulation.

Effects of temperature on the final stages of sexual maturation in Atlantic salmon (Salmo salar L.).

Maturing male and female Atlantic salmon (Salmo salar L.) were held under three temperature regimes for 10 weeks between September and December: warm (constant 14-16 °C), ambient (decreasing from 11 to 5 °C), and cold (decreasing from 7 to 3 °C). Blood samples were analyzed for plasma steroid levels, and the fish were inspected for the presence of expressible milt (total volume and spermatocrit) and ovulation weekly.

Cardiac responses to elevated seawater temperature in Atlantic salmon.

Background: Atlantic salmon aquaculture operations in the Northern hemisphere experience large seasonal fluctuations in seawater temperature. With summer temperatures often peaking around 18-20°C there is growing concern about the effects on fish health and performance. Since the heart has a major role in the physiological plasticity and acclimation to different thermal conditions in fish, we wanted to investigate how three and eight weeks exposure of adult Atlantic salmon to 19°C, previously shown to significantly reduce growth performance, affected expression of relevant genes and proteins in cardiac tissues under experimental conditions.