Age, growth and maturation of Sthenoteuthis oualaniensis in the eastern tropical Pacific Ocean by statolith analysis

The age, growth and maturation of the purpleback flying squid, Sthenoteuthis oualaniensis, were determined by statolith analysis using data from April-June 2013 surveys in the equatorial eastern tropical Pacific Ocean (ETPO). Three distinct growth zones with different width increments (postnuclear, dark and peripheral zones), checks and aberrant microstructures were found in the statoliths. The longevity of the species was a maximum of 0.5 years. Hatching dates were from November to March, with a peak between January and February. The high percentage of mature females (69.5%) suggested that there was at least another peak after April-June, and the study area might be a potential spawning ground for the species. Size and age at first maturity were 192-mm mantle length (ML) and 114 days for females, whereas males began to mature at 137mm ML and 87 days.