Temporal repeatability of relative standard metabolic rate in juvenile Atlantic salmon and its relation to life history variation

There was a strong correlation between the relative standard metabolic rate (rSMR) values of individual Atlantic salmon Salmo salar L. measured 5 and 22 weeks after first feeding in June and October respectively (Pearson's r= 0.68, 26 d.f.. P<0.001). However, this is a conservative estimate of repeat ability as two separate regressions were used to calculate SMR in October d ue to the separation of the population into an upper modal group made up of early migrants and a lower modal group comprised of delayed migrants. SMR values in June and October were similar (paired t test, t = - 0.85. 27 d.f. , P>0.05) when expressed as the percentage deviation from those predicted f or a fish of that size based on the body mass/SMR relations in June or Octo ber indicating that relative standard metabolic rates were stable over time when food was trot limiting. rSMR status was maintained in 19 of the 28 fi sh (i.e. 68%) between the two measures, rSMR status was correlated with lif e history strategy: salmon fry with a high SMR in June were more likely to become smolts Juring the autumn than those with a low SMR. (C) 2000 The Fis heries Society of the British Isles.