Growth and life span of the small octopus Octopus tehuelchus in San Matías Gulf (Patagonia): three decades of study

Abstract

Phenotypic plasticity in response to environmental variability is one of the main characteristics of cephalopods. This study compares growth and life span of Octopus tehuelchus in different coastal environments of San Matías Gulf (Patagonia) at three different periods.The progression of maturity jointly with modal progression analysis and the detection of hatchlings in the natural environment were used to differentiate cohorts and assign ages.Growth was described using the oscillatory von Bertalanffy growth model. Within San Antonio Bay, O. tehuelchus seems to have the most favourable conditions for an extended spawning season and the development of two sub-annual cohorts. O.tehuelchus growth is strongly seasonal with slow growth rates during winter. There were differences in the growth pattern between sites and particularly between subannual cohorts in San Antonio Bay. The growth pattern in each site seems to be similar along the last twenty-six years. The results of our study make evident the variability and plasticity of O. tehuelchus in response to the environment.