Abstract
Larval muscle development in Atlantic salmon is known to be affected by temperature; however, the long term effects and possible mechanisms involved are less well understood. Therefore, the aim of this study was to evaluate the influence of egg incubation temperature on post-hatch muscle growth and fish activity. Salmon eggs were incubated at either 10 degrees C or 5 degrees C from fertilization until hatching, then subsequently both groups were reared at 5 degrees C. Fish from both groups were sampled at the eyed stage, 6 and 21 weeks after first feeding, for muscle cellularity analysis and immunocytochemistry. In addition, to try to establish a mechanism for altered growth, the activity of the fish was measured at 3, 6 and 21 weeks after first feeding. Our results demonstrate that whereas fish incubated at 10 degrees C grow faster, the fish incubated at 5 degrees C show a more sustained period of muscle growth and by 21 weeks are significantly longer, heavier and have more muscle fibres than those fish incubated at a higher temperature. We also demonstrate that fish raised at 5 degrees C show increased food seeking activity throughout development and that this may explain their sustained growth and muscle development. These results taken together, demonstrate that egg incubation temperature up to hatching in salmon is critical for longer term muscle growth, twinned with increased activity. This is of interest to the aquaculture industry in term of the production of good quality fish protein.
Highlights
Global production of farmed fish has more than doubled in the past 15·years
Our results demonstrate that whereas fish incubated at 10°C grow faster, the fish incubated at 5°C show a more sustained period of muscle growth and by 21·weeks are significantly longer, heavier and have more muscle fibres than those fish incubated at a higher temperature
We demonstrate that fish raised at 5°C show increased food seeking activity throughout development and that this may explain their sustained growth and muscle development
Summary
Global production of farmed fish has more than doubled in the past 15·years (reviewed by Naylor et al, 2000). Muscle development and growth in fish occurs as a combination of muscle hypertrophy (the increase in size of existing fibres) and muscle hyperplasia (the recruitment of new muscle fibres) (reviewed by Koumans and Akster, 1995; Rowlerson and Veggetti, 2001). This process continues throughout development into adulthood in most fish species (Greer-Walker, 1970; Stickland, 1983; Weatherley and Gill, 1984; Weatherley et al, 1988). This is in contrast to mammals in which hyperplasia stops at around the time of birth (Campion, 1984; Goldspink, 1972; Rayne and Crawford, 1975)
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