Age and growth of the snipefish, Macrorhamphosus spp., in the Portuguese continental waters
Age and growth of the snipefish was studied based on samples collected in the Portuguese continental waters between 1996 and 1998. Analysis was conducted for two species, Macrorhamphosus scolopax and M. gracilis and for both species combined. Total length ranged from 5.5 to 18.2 cm for M. scolopax and from 5.4 to 17.3 cm for M. gracilis. Length–weight relationships were described for M. scolopax (a=0.00401; b=3.127), M. gracilis (a=0.00459; b=3.006) and both combined (a=0.00240; b=3.282). Age estimation, based on otolith observations, resulted in six and five years maximum age attributed to M. scolopax and M. gracilis, respectively. Back-calculation analysis based on a polynomial relation of the otolith radius on total length provided significantly smaller lengths-at-age compared with observed lengths. The von Bertalanffy growth curves fitted to observed lengths-at-age provided parameters of L[infty infinity]=15.7 cm, K=0.654, t0=−1.066 for M. scolopax; L[infty infinity]=14.2 cm, K=0.694, t0=−0.954 for M. gracilis and L[infty infinity]=15.8 cm, K=0.470, t0=−1.408 for both species combined.