15N-enrichment of an aquaculture diet and tracing of cage culture waste in an estuarine environment

Citation

Felsing M, Telfer T & Glencross B (2006) 15N-enrichment of an aquaculture diet and tracing of cage culture waste in an estuarine environment. Journal of Applied Ichthyology, 22 (5), pp. 419-426. https://doi.org/10.1111/j.1439-0426.2006.00744.x

Abstract
A method was developed to use the stable isotope 15N to trace the fate of cage aquaculture-derived nutrients at an experimental cage aquaculture site in Fremantle Harbour, Western Australia. Artificial enrichment of a finfish diet in 15N was achieved through the enrichment of the macroalgae Ulva rigida, which was fed to rainbow trout (Oncorhynchus mykiss) to produce 15N-labelled fishmeal. From the subsequently produced fishmeal, a pelleted feed with a 15N signal of 298 ± 58‰ (mean ± SE) was produced and fed to pink snapper (Pagrus auratus) in a seacage. Strong enrichment (15N range: 38-53‰) was detected in primary producers and suspended particulate organic matter in the vicinity of the cage immediately following enrichment, and a delayed uptake (to 15N 15.9 ± 0.2‰, mean ± SE) was detected in deposit feeders under the cage 14 days following enrichment. No further enrichment signal could be detected near the cage in this short-term trial. The limited accumulation of aquaculture waste in the vicinity of cages was supported by findings from concurrent environmental monitoring. It was concluded that artificially enriched aquaculture feeds provide a sensitive method for tracing aquaculture wastes in the environment, but that further development of the technique is required to make it viable for more widespread use.

Journal
Journal of Applied Ichthyology: Volume 22, Issue 5