Comparative Metabolic Rates of Common Western North Atlantic Sciaenid Fishes

The resting metabolic rates of (RMR) western North Atlantic sciaenids such as Atlantic croaker (Micropogonias undulatus), spot (Leiostomus xanthurus), and kingfishes (Menticirrhus spp.) as well as the active metabolic rates (AMR) of Atlantic croaker and spot were investigated to facilitate inter- and intraspecific comparisons of their energetic ecology.  The RMRs of Atlantic croaker and spot were typical for fishes with similar lifestyles.  Kingfish RMRs were significantly elevated relative to those of croaker and spot, but below those of high energy demand species such as tunas (Thunnus spp.) and dolphin fish (Coryphaena hippurus).  Repeated measures nonlinear mixed effects models were applied to account for within-individual autocorrelation and corrected for non-constant variance typical of noisy AMR datasets.  Repeated measures models incorporating autoregressive first-order (AR(1)) and autoregressive moving average (ARMA) covariances provided significantly superior fits, more precise parameter estimates (i.e., reduced standard errors), and y-intercept estimates that more closely approximated measured RMR for croaker and spot than standard least-squares regression procedures.