Self-selection of diets with different contents of arachidonic acid by Senegalese sole (Solea senegalensis) broodstock

Abstract

Senegalese sole (Solea senegalensis) failed to reproduce and spawn viable eggs when bred and reared in captivity (first generation G1 cultured broodstock). Cultured sole were also shown to have significantly lower levels of arachidonic fatty acid (20:4n−6, ARA) in reproductive tissues compared to wild counterparts. However, to date no information about ARA requirements of Senegalese sole broodstock (wild or cultured) has been available. The present study was designed to determine dietary ARA preferences of adult G1 Senegalese sole by the use of automated demand feeders. For this purpose, three groups of 16 (eight females and eight males) G1 fish were offered to select between two diets, one with high (6.0% of total fatty acids, TFA) and another with low (0.7% TFA) ARA content. The experiment was conducted for 16 consecutive months. The results revealed that Senegalese sole changed the preference for ARA during the year, in correlation with the seasonal water temperature (r2=0.7), and with periods of high and low demand of total food ingested. Thus, a high ARA (3.9% TFA) selection was observed in summer and early-autumn, whereas low ARA (2.2% TFA) selection occurred in winter. The average ARA demanded during the whole year was 3.0% TFA, with a resultant high level of ARA in the tissues of the fish; especially in male testis (8.8% TFA). These results should be considered when formulating seasonal diets to suit sole broodstock preferences in ARA in intensive aquaculture.