Fatty acid composition and age estimation of wild Octopus vulgaris paralarvae

The fatty acid (FA) profile of wild Octopus vulgaris paralarvae of estimated age was individually analyzed for the very first time in order to establish a reference for comparison in rearing and nutritional studies. Age of each paralarvae was estimated by analysing daily increments on lateral hood surface of beaks. Wild paralarvae age ranged between 6 and 8 days and their FA composition resembled that from hatchlings produced under culture conditions. However, when compared with the FA composition of up to 20 days old cultured paralarvae described in the bibliography, some striking differences were found. Results showed higher levels of docosahexaenoic acid (22:6n − 3, DHA), lower contents of 18:1n − 9, 18:1n − 7 and 18:2n − 6 and negligible levels of 18:3n − 3 in wild paralarvae, when collated to reared one. These results seem to indicate that preys/diets supplied to cultured paralarvae fail to resemble paralarval natural composition and as a result do not fulfil their FA requirement. The individual applied technique developed in this study will allow to refine the study of wild paralarvae along its development, as well as to compare wild and cultured paralarvae of similar age. Statement of relevance Artemia does not fulfil paralarval fatty acid requirements.
This study was funded by Spanish Government under Projects OCTOPHYS (Ref. AGL2010-22120-C03), OCTOWELF (Ref. AGL2013-49101-C2-1-R) and LARECO (CTM2011-25929). Most of the authors of this paper participate to the COST network, Action FA1301 (CephsInAction) focussing on Cephalopod welfare. D. Garrido was financed by a Ph.D. grant by Spanish Institute of Oceanography (BOE 3rd November 2011).