Comparative performances of juvenile abalone (Haliotis tuberculata coccinea Reeve) fed enriched vs non-enriched macroalgae: Effect on growth and body composition

Abalone Haliotis tuberculata coccinea Reeve (1846), is a target species for diversification of European aquaculture production. Taking into account that sustainable, eco-friendly production methods are to be a part of future expansion of the abalone industry, growth performance of juvenile abalone reared in an integrated culture system was evaluated and compared with that of abalone fed non-enriched macroalgae. Four macroalgae treatments, three monospecific: Ulva rigida (UN), Hypnea spinella (HN) and Gracilaria cornea (GN) and a composite one (MN), were produced out of fishpond wastewater effluents, while other four control treatments consisted of the same species reared in fresh seawater (U; H; G; M). Seaweeds reared in fishpond wastewater effluents increased their protein content from 11–17% to 29–34%. Lipids consisted mainly of saturated fatty acids (SFA) (43–60%), palmitic acid being the most abundant fatty acid (40–47%). Highest EPA percentage was found in red algae H. spinella (6.9%), being ten times higher than that of U. rigida (0.7%). All the algae tested contained very low levels of arachinodic acid (0.1–1.6%) and docosahexaenoic acid (0.5–3%). Protein levels in foot muscle (74–76%) did not differ significantly (P < 0.05) among treatments. Survival was generally high, ranging from 85 to 100%. Weight gain (17–561%) and SGR (0.2–2.3%) were positively related to protein content; whereas, protein efficiency ratio (PER) (0.5–3.7) was negative correlated. PE ratios increased by 82–159% (DW) as a function of the enrichment among the different diets. Food conversion ratio (FCR) (7–188) improved according to the increase in PER. Overall, biofilter-produced macroalgae showed a significantly higher dietary value compared to the control treatments. Similarly, animals fed the mixed diets performed significantly better than those fed a single algal diet. Feeding G. cornea led to the lowest growth performance probably due to the lowest feed intake. The results clearly indicate that H. tuberculata coccinea growout can efficiently take place in an integrated-culture system suggesting that on-farm seaweed-abalone production could be part of future development of the abalone industry in the Canary Islands.