The growth of post-weaning abalone (Haliotis midae Linnaeus) fed commercially available formulated feeds supplemented with fresh wild seaweed

Abstract

The effect of five formulated feeds, supplemented with fresh wild seaweed on the growth of post-weaning juvenile abalone (6 - 20 mm shell length), Haliotis midae Linnaeus was investigated by means of a growth trial at a commercial abalone farm over a period of 11 months. The experiment included 10 diet treatments with two replicates each (n = 50 individuals per replicate). The first five diet treatments comprised of four fishmeal-based formulated feeds: Abfeed®, Adam & Amos® ‘a’, Adam & Amos® ‘b’ and Adam & Amos® ‘c’; and an all-seaweed-based formulated pellet: FeedX. The additional five diet treatments comprised the formulated feeds above, supplemented with fresh, wild seaweeds; the kelp, Ecklonia maxima (5-15% protein) and Ulva lactuca (3.7-19.9% protein). The fishmeal-based protein feeds produced significantly better growth than the all-seaweed-based protein feed, FeedX (0.49±0.03 SGR; 27.15±0.02 DISL; 0.864 final CF). Abfeed® (1.00±0.02 SGR; 60.79±0.04 DISL; 1.312 final CF) performed best of all the formulated feeds. Supplementation with fresh wild seaweed, however, significantly improved growth of all abalone with supplemented Abfeed® (1.05±0.02 SGR; 63.61±0.05 DISL; 1.447 final CF) outperforming all supplemented feeds. More striking though was that the condition factor of abalone fed that feed (FeedX) that performed particularly poorly in the growth trials was dramatically improved by supplementation. The results of this study show that supplementation with fresh wild seaweed enhances the growth of abalone reared on formulated feeds.