Comparative study of age estimation in wild and cultured Octopus vulgaris paralarvae: effect of temperature and diet

摘要

The common octopus Octopus vulgaris is a highly valuable species worldwide, but to understand its population dynamics and requirements under culture conditions, it is crucial to improve our knowledge about its planktonic stages. Previous studies validating daily beak growth increments in these stages allowed age estimation and comparison of wild and cultured paralarvae. We aimed to improve age estimations in captivity, addressing the effect of temperature and diet, to obtain an accurate estimation of age in wild specimens collected from the coast to the open ocean off NW Spain and Morocco. We analysed the beak growth increments of reared paralarvae at 14 and 21?°C with 2 different crustacean prey taxa (Artemia and spider crab Maja brachydactyla zoeae) over 30 d. Daily increment deposition at 21?°C was confirmed, whereas 1 increment d-1 was recorded at 14?°C. The width of the reading area grew accordingly with age; therefore, this beak region may be suitable for age estimation. A general linear model (GLM) analysis showed that temperature and the interaction of age ?? temperature significantly influenced increment deposition, whereas diet did not. The number of growth rings recorded in wild paralarvae beaks ranged from 0-8 on the coast, 7-11 on the continental shelf and 2-28 in the open ocean. Corrected age estimates of wild paralarvae were obtained with the GLM using the mean temperatures recorded in the wild, supporting the hypothesis that O. vulgaris leave the coastal area and develop in the open ocean transported by upwelling filaments.