The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla, under farm conditions

Journal Publication ResearchOnline@JCU
Onomu, Abigail J.;Vine, Niall G.;Cyrus, Mark D.;Macey, Brett M.;Bolton, John J.
Abstract

This gonad enhancement study investigates the effect of different fresh and formulated feeds and feeding regimes on the growth and gonad quality of wild-collected adult sea urchin, Tripneustes gratilla, under farm conditions for over 18 weeks. In the first 12 weeks (phase 1), urchins were fed fresh Ulva rigida (U); a 50:50 mixture of fresh U. rigida and Gracilaria gracilis (UG); fresh G. gracilis (G) and a formulated diet 20U (containing 20% U. rigida), and in the final 6 weeks (phase 2) of the study, diet was changed to a formulated feed (20U diet). By the end of phase 1, urchins fed the 20U diet produced gonads (50.72 ± 5.4 g) that were significantly heavier (p < .001) than the gonads of urchins fed the fresh seaweed diets (U, UG & G). By the end of phase 2, gonad weight of urchins in treatment groups UG-20U and G-20U were similar to those fed the 20U-20U diet. Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, p = .029) and poorer quality, compared with urchins in the U-20U group. This gonad enhancement study, conducted on wild collected adult T. gratilla, has shown that a formulated feed (20U diet) can enhance gonad growth and produce commercially acceptable gonads. This farm-based study supports previous findings from aquarium-based studies by our group and indicates that short-term sea urchin gonad enhancement can be carried out under farm conditions in South Africa.

Journal

Aquaculture Research

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Volume

51

ISBN/ISSN

1365-2109

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Issue

10

Pages Count

16

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Publisher

Blackwell Publishing

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DOI

10.1111/are.14752