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Type: Journal article
Title: Dissolved nutrient release from solid wastes of southern bluefin tuna (Thunnus maccoyii Castelnau) aquaculture
Author: Fernandes, Milena
Angove, Michael
Sedawie, Talya
Cheshire, Anthony
Citation: Aquaculture Research, 2007; 38 (4):388-397
Publisher: Blackwell Science Ltd
Issue Date: 2007
ISSN: 1355-557X
School/Discipline: School of Earth and Environmental Sciences
Abstract: Finfish pens are point sources of dissolved nutrients released from fish metabolism or degradation of solid wastes. Nutrients leaching from uneaten feed and faeces are not usually quantified in mass budgets for these systems, leading to an overestimation of fish retention or deposition to the seabed. In this study, we investigated nutrient leaching from pellets and baitfish feed as well as faeces of southern bluefin tuna (Thunnus maccoyii) into seawater. Faeces were nitrogen depleted (51-54mg N g−1 dw) and phosphorus enriched (62-72 mg P g−1 dw) compared with feeds (83-111 mg N g−1 dw and 17-21 mg P g−1 dw). Less phosphorus was available for leaching from pellets and faeces of pellet-fed tuna (5-6%) than from baitfish and faeces of baitfish-fed tuna (17-21%). The proportion of soluble nitrogen in pellets (15%) was also lower than in baitfish and faeces (35-43%). Leaching loads for a feed conversion ratio of 5 were estimated as 22 and 26 kg N tonne−1 growth when baitfish or pellets were used as feed respectively. Phosphorus loads were estimated as 15 and 4 kg P tonne−1 growth respectively. More than 90% of nitrogen loads, and approximately 50% of phosphorus, are likely to be released into seawater before solid wastes reach the seafloor.
Keywords: aquaculture; wastes; nutrients; leaching; settling rates
Description: © 2008 Ingenta
RMID: 0020075042
DOI: 10.1111/j.1365-2109.2007.01680.x
Appears in Collections:Earth and Environmental Sciences publications

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