Fisheries Research Articles

A new proportionality-based back-calculation approach, which employs traditional forms of growth equations, improves estimates of length at age

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Canadian Journal of Fisheries and Aquatic Sciences


Print: 0706-652X Electronic: 1205-7533


Aquaculture and Fisheries | Marine Biology


The performance of a new proportionality-based back-calculation approach, describing the relationship among length, otolith size, and age using traditional growth curves and assuming a bivariate distribution of deviations from those curves, was evaluated. Cross-validation was used for six teleost species to compare predictions of expected lengths or otolith sizes at age, given otolith size or length, respectively, with those of other proportionality-based approaches that incorporate age. For four species, and particularly Acanthopagrus butcheri when using a biological intercept, better estimates were produced using the new model than were produced using the regression equations in the other back-calculation approaches. Back-calculated lengths for A. butcheri estimated using this model were more consistent with observed lengths, particularly when employing a biological intercept, than those obtained using other proportionality-based approaches and also a constraint-based approach known to produce reliable estimates. By selecting somatic and otolith growth curves from a suite of alternatives to better describe the relationships among length, otolith size, and age, the new approach is likely to produce more reliable estimates of back-calculated length for other species.



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