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Fig. 2. The number of fast muscle fibres per trunk cross-section at the level of
the first dorsal fin ray in a subset of Atlantic salmon (Salmo salar
L.) reared under conditions of extended winter day length (yellow symbols,
dashed line; period of continuous lighting shown by yellow box) or at ambient
photoperiod (blue symbols, solid line). The broken blue line shows sunrise and
sunset (Greenwich Mean Time, GMT) at Fort William, and the green line
illustrates daily recordings of sea temperature. The results are means
± S.E.M. The number of fish sampled from each cage is shown
in Table 2.