Age and growth of the squid Sepioteuthis lessoniana in N.W. Luzon, philippines

Abstract

The statoliths of 33 Sepioteuthis lessoniana from Bolinao, north-western Luzon, Philippines, were examined microscopically for growth increments. The daily nature of the increments was verified for captive specimens (<6 cm) kept in a tank containing Alizarin solution and fed with shrimps previously soaked in Alizarin solution. The ages ranged from 30–40 days in juveniles (19–33 mm dorsal mantle length DML) to 62–132 days in adults (62–315 mm DML). The growth rates estimated (0.5 mm·day⁻¹ in adults) were much higher than those estimated by length-frequency analysis, but compatible with published estimates based on the statoliths of specimens sampled in Australia and Japan. The discrepancy between the results of length-frequency analysis and statolith ageing is attributed, at least in part, to underestimation of the age of older squid.