Live prey enrichment and artificial microdiets for larviculture of Atlantic red porgy Pagrus pagrus

Abstract

In the first experiment the effects of rotifer enrichment and feeding frequency on larval performance of red porgy Pagrus pagrus were studied. Larvae (2 days post-hatching = 2 dph) were fed s-type rotifers (∼20 rotifers/mL) enriched with one of the four different treatment media: Rotifer Diet (microalgae Nannochloropsis oculata and Tetraselmis chuii), DHA Protein Selco, Algamac 3000 (Schizochytrium sp.) and Algamac + ARA (arachidonic acid). Larvae were fed daily at full ration or twice daily at half ration. Larval growth and survival (mean = 22.8%) were satisfactory through 16 dph under all treatments; however, resistance to hyposaline challenge (Survival Activity Index = SAI) was positively correlated (P < 0.01) with DHA concentration of rotifers, and SAI appeared highest in the Algamac + ARA treatment. In the second experiment the effects of Artemia enrichment on larval performance were compared from 18 dph through pre-metamorphosis (33 dph). Larvae were fed Artemia (0.5–3.0/mL) enriched with two different media Algamac 3000 and DC DHA Selco, or unenriched Artemia (control). Both media improved DHA levels in Artemia and growth and survival (36.7–54.6%) of larvae, while larvae fed unenriched Artemia showed poor growth and survival (5.2%). In the third experiment a University of North Carolina Wilmington microbound diet (MBD) and two commercial microdiets (Gemma Micro and Otohime) were evaluated. The MBD contained different protein sources (i.e., menhaden, squid and krill meal, soy protein concentrate) and attractants. Beginning 16 dph, live feeds and microdiets were co-fed to three treatment groups of larvae: (1) Gemma, (2) MBD, and (3) Otohime. Larval performance on the UNCW-MBD was comparable to the commercial microdiets, with no significant differences in larval survival, DHA, or total n-3 PUFA content through 32 dph. Results delineate more effective rearing protocols for larviculture of Atlantic red porgy juveniles. Keywords: Red porgy, Live prey enrichment, Rotifers, Artemia, Microdiets, Microbound diets, Essential fatty acids