Different traditional and geometric morphometric approaches are explored for the size reconstruction of European (Acipenser sturio) and Atlantic sturgeon (A. oxyrinchus) on the basis of isolated bony scutes. The relationship between fish length and different scute measurements was tested with linear regressions using 58 modern sturgeons from museum collections. As the accuracy of this approach was limited, we explored the possibility of determining the position of an isolated scute within its row on the basis of its shape or dimension. In the dorsal and lateral rows, the shape and dimension of the scutes change along the antero-posterior axis, but this difference is too gradual to allow establishing the original position of an isolated scute within the row. No consistent changes in the shape or dimensions of ventral scutes were observed according to their place within the row. Differences in scute shape or dimensions between large and small animals have been documented as well, but these differences were not sufficiently pronounced for an accurate estimation of size. We conclude that isolated scutes cannot provide very accurate fish length reconstructions. However, the regression models presented in this study, allow verifying whether individual lateral and dorsal scutes belonged to sturgeons larger than 1m total length. In that case they can be identified to species level on the basis of their surface ornamentation, which is size dependent. |
