Revista Chilena de Historia Natural 84 (1): 33-49, 2011
RESEARCH ARTICLE
Growth models fitted to Dipturus chilensis length-at-age data support a
two-phase growth
Age and growth for the beaked skate was estimated from bands in the vertebral
centra of 689 individuals obtained from incidental catches of the Argentine hake (Merluccius hubbsi) fishery.
Age bias plots and indices of precision indicated that ageing method was precise and unbiased (% CV = 3 % PA = 82.09
%). Edge and marginal increment analysis of the vertebrae support the hypothesis of annual band pair deposition. Three
growth models were fitted to length-at-age and the two-phase growth model produced the best fit. This feature has never
been described before for D. chilensis and can be related to changes in energy allocation and the shift from
juvenile to adult phase. The unrealistic biological estimates of the von Bertalanffy growth model illustrates the importance
of fitting alternative models to the data. Female beaked skates reached greater size in length (L<sub>¥</sub>) as well as in disc width (L<sub>¥</sub>= 138.2 cm; DW<sub>¥</sub>= 92.46 cm) and have lower growth rate (k = 0.08 yr<sup>-
1</sup>) than males (L<sub>¥</sub>= 106.7 cm; DW<sub>¥</sub>= 74.52 cm; k = 0.121 yr<sup>-1</sup>). This study provides
basic information on age and growth for the beaked skate, D. chilensis, which were previously not available for
its south Atlantic range of distribution.
Key words:
beaked skate,
Dipturus chilensis, growth, two-phase growth
