Freshwater environment affects growth rate and muscle fibre recruitment in seawater stages of Atlantic salmon (Salmo salarL.)

Abstract

The influence of freshwater environment on muscle growth in seawater was investigated in an inbred population of farmed Atlantic salmon (Salmo salar L.). The offspring from a minimum of 64 families per group were incubated at either ambient temperature (ambient treatment) or in heated water (heated treatment). Growth was investigated using a mixed-effect statistical model with repeated measures, which included terms for treatment effect and random fish effects for individual growth rate (α) and the instantaneous growth rate per unit change in temperature (γ). Prior to seawater transfer, fish were heavier in the heated (61.6±1.0·g; N=298) than in the ambient (34.1±0.4·g; N=206) treatments, reflecting their greater growth opportunity: 4872·degree-days and 4281·degree-days, respectively. However, the subsequent growth rate of the heated group was lower, such that treatments had a similar body mass (3.7-3.9·kg) after approximately 450·days in seawater. The total crosssectional area of fast muscle and the number (FN) and size distribution of the fibres was determined in a subset of the fish. We tested the hypothesis that freshwater temperature regime affected the rate of recruitment and hypertrophy of muscle fibres. There were differences in FN between treatments and a significant age×treatment interaction but no significant cage effect (ANOVA). Cessation of fibre recruitment was identified by the absence of fibres of <10·µm diameter. The maximum fibre number was 22.4% more in the ambient (9.3×10 5 ±2.0×10 4 than in the heated (7.6×10 5 ±1.5×10 4 ) treatments (N=44 and 40 fish, respectively; P<0.001). For fish that had completed fibre recruitment, there was a significant correlation between FN and individual growth rate, explaining 35% of the total variation. The density of myogenic progenitor cells was quantified using an antibody to c-met and was approximately 2-fold higher in the ambient than in the heated group, equivalent to 2-3% of the total muscle nuclei. The number of myonuclei in isolated fibre segments showed a linear relationship with fibre diameter. On average, there were 20.6% more myonuclei in 200-µm-diameter fibres isolated from the ambient (3734·myonuclei·cm -1 ) than from the heated (3097·myonuclei·cm -1 ) treatments. The maximum fibre diameter was greater in heated than in ambient groups, whereas the age×treatment interaction was not significantly different (ANCOVA). There were also no consistent differences in the rate of hypertrophy of muscle fibres between treatments. It was concluded that freshwater temperature regime affected fibre number and the nuclear content of fast muscle in seawater but not the rate of fibre hypertrophy. The mechanisms and life history consequences of developmental plasticity in fibre number are discussed.

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“…In contrast, the 16L:8D group did not reach the size of the other groups. In salmon, the body weight was also higher in the 24L group than in the natural photoperiod group four months and two weeks after transferring the salmons to natural photoperiod (Johnston et al, 2003b(Johnston et al, , 2004. In two groups of cod reared at 24L and at a natural photoperiod for 120 days, Nagasawa et al (2012) observed that the muscle growth of the 24L group was greater not only at 120 days, but also two months after the two groups were transferred to a natural photoperiod (at 180 days).…”

Performance and Muscular Development of Nile Tilapia Larvae (&lt;i&gt;Oreochromis niloticus&lt;/i&gt;) Fed Increasing Concentrations of Phenylalanine

“…Jhonston et al [32] and Zimmerman & Lowery [33] state that muscular development by hyperplasia is replaced by hypertrophy of the muscular cells when a fish reaches 44% of its final size; however, this can vary with species. Furthermore, Rowlerson and Veggetti [30] reported that fish have an undetermined growth, which makes it difficult to establish the final weight of an adult.…”

Rapid evolution of muscle fibre number in post-glacial populations of Arctic charrSalvelinus alpinus

“…In the present study, we tested the null hypothesis that muscle cellularity was the same in all morphs of Arctic charr in Thingvallavatn, reflecting their recent diversification. The number of muscle fibres formed at each phase of myogenesis is sensitive to egg incubation temperature (Stickland et al, 1988;Johnston et al, 2000aJohnston et al, ,b, 2003cJohnston and Hall, 2004). Variation in spawning time and the influence of cold groundwater on spawning sites give rise to the possibility of differences in development temperature between morphs (Skúlason et al, 1989a).…”

“…The environmental temperature during early development has been shown to affect the number of muscle fibres produced at each stage of myogenesis in salmonids (Stickland et al, 1988;Johnston et al, 2000bJohnston et al, , 2003c) and other teleosts (Ayala et al, 2000;Johnston et al, 1998). Temperature regimes that result in a higher fibre number have been associated with a higher density of myogenic progenitor cells (Johnston et al, 2000a(Johnston et al, , 2003c.…”

“…Temperature regimes that result in a higher fibre number have been associated with a higher density of myogenic progenitor cells (Johnston et al, 2000a(Johnston et al, , 2003c. The effect of this developmental plasticity varies with the temperature profile during embryogenesis and can show marked differences between species and between populations of the same species (Johnston et al, 2000a,b;Johnston and Hall, 2004).…”