On the reliability of the growth rings in two species of the family Characidae in the Sudan
The scales, opercula and vertebrae from 69 Hydrocyon forskali and 63 Alestes dentex were investigated for their reliability as aging structures. In both species the scales were unreliable due to their regenerative property, in spite of the clarity of their growth rings. Back-calculated lengths from the first growth ring laid on opercula and vertebrae resulted in values that coincided with the annual growth of the two species. In H. forskali, the mean back-calculated length from the two bones were 16.2 ± 5.9 and 16.8 ± 4.4 respectively, and for A. dentex, 11.1 ± 1.7 and 12.8 ± 1.8, respectively. Predictive equations for bone radius from fish length were written for both species. In this study, reliability was maximal between the observed and back-calculated lengths for both species (r > 0.95).
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences medicales
- 4 - maladies metaboliques