Improved survival and growth in Octopus vulgaris paralarvae by feeding large type Artemia and Pacific sandeel, Ammodytes personatus

Rearing experiments of common octopus, Octopus vulgaris, paralarvae were carried out during the first month of life by feeding with large type Artemia or small type Artemia supplemented with defrozen flakes of Pacific sandeel, Ammodytes personatus. Two experiments, based on different scale tanks of four 500 l circular tanks and two 4000 l rectangular tanks, were carried out in June to July 2003 to investigate the survival, growth and HUFA composition of the paralarvae and food organisms. The survival rate of paralarvae was significantly higher in the large type Artemia supplied groups (47.4% and 45.9%) than the small type Artemia supplied groups (8.8% and 2.7%). Similarly, the mean wet weight was 26.2 and 37.3 mg for the 25 and 32 day old paralarvae in the large type Artemia groups while 20.3 and 18.2 mg in the small type Artemia groups. The survival rate and growth of the large type Artemia groups were higher than the small type Artemia groups and the values given in the previous studies. Feeding large type Artemia and sandeel flakes was concluded as effective for improving survival and growth of the common octopus paralarvae. The DHA/EPA ratio in the 32 day old paralarvae of both Artemia supplied groups was equal 1.5, similar to that of hatchlings and wild subadults. Supplementing sandeel flakes improved the DHA/EPA ratio of the paralarvae, since both types of Artemia contained only minimal DHA. However, the reason(s) for the improved survival rate and growth between the large type Artemia supplied group and small type Artemia supplied group still remain to be solved.