Patterns of muscle growth in early and late maturing populations of Atlantic salmon (Salmo salar L.)

• Main Authors: Johnston, I A, Alderson, R, Sandham, C, Mitchell, D, Selkirk, C, Dingwall, A, Nickell, D, Baker, R, Robertson, B, Whyte, D, Springate, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2000
• Subjects: Atlantic salmon; muscle fibres; growth; sexual maturation; ADULT SKELETAL-MUSCLE; RAINBOW-TROUT; SATELLITE CELLS; SOMATIC GROWTH; ENERGY-METABOLISM; MYOGENIC CELLS; WHITE MUSCLE; AXIAL MUSCLE; LIFE-HISTORY; FIBER TYPES; Salmo salar
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/patterns-of-muscle-growth-in-early-and-late-maturing-populations-of-atlantic-salmon-salmo-salar-l(f18ad49d-b0f3-4a3f-9baf-203e3d49c88d).html; http://www.scopus.com/inward/record.url?scp=0034597416&partnerID=8YFLogxK

Muscle growth was investigated in two populations of Atlantic salmon (Salmo salar L) derived from an early maturing stock of West Coast Scottish origin (strain X) and a late maturing stock (strain Y) of Norwegian origin. Fish from six families per population were PIT-tagged and reared together in a 5x5x5 m sea cage between April 1997 and September 1998. The distribution of muscle fibre diameters in different age classes was investigated using non-parametric smoothing and bootstrapping techniques. Body mass and the total cross-sectional area of white muscle at the level of the first dorsal fin ray increased at a significantly faster rate in strain X than in strain Y after the first 6 months in seawater (April-October). The relative contributions of fibre recruitment and hypertrophy to muscle growth were very different for the two populations. The number of white muscle fibres per trunk cross-section was around 150,000 in June and 250,000 in July for both populations. The majority of fish sampled in June, July and August 1997 showed a unimodal distribution of fibre diameter. Between July and August fish from strain Y recruited two times more fibres for each square millimeter increase in white muscle cross-sectional area than fish from strain X. Fibre number in strain X had caught up with strain Y by January with 545,000 fibres per cross-section. There was no significant increase in the number of white fibres in strain Y between January and September 1998, such that growth was entirely by fibre hypertrophy. In contrast, fibre number continued to increase in strain X until the final sample in June, reaching 718,000 per trunk cross-section. All fish showed a bimodal distribution of fibre diameter in the October and subsequent samples with significant differences between strains. The right-hand peak of the distribution was shifted towards higher diameters in strain X than in strain Y, indicating superior hypertrophic growth performance in the early maturing population. For example, in the May 1998 sample, the 95th ...