Modelling of Taste-Taint in Fish ... 53was the difference of two exponential terms of simultaneous taint uptake and
taint elimination with growth time.
An advantage of their model is that it is ‘generalised’ in form and can be
conveniently simulated in standard spread-sheeting tools for use by a range of
users of different sophistication. This appears to be the first model that might
be used to minimize taint in RAS farmed fish.
The model was illustrated with independent data for farmed barramundi
(Lates calcarifer), an important RAS fish in Australia and globally, for both
constant and varying concentration of GSM and MIB in the RAS growth
water. However, there has not been extensive data published on taint
accumulation as either GSM or MIB with RAS systems. They have however
obtained limited data for taint as GSM from growth ponds from the
Department of Agriculture Fisheries and Forestry, Australia (DAFF) (S.
Poole, pers. comm.) for this study.
The model was used to simulate taint accumulation up to the consumer
rejection threshold (~ 0.7 μg kg-^1 ) and also to simulate the impact of varying
growth water temperature on taste-taint accumulation in the harvested fish-
flesh. More generally however, if a fish is to grow for a longer (indefinite)
period, then an ‘S-curve’ for growth has been proposed to make the model
more universal and to generalize it for a range of other RAS fish species
(Hathurusingha and Davey, 2014; Davey and Hathurusingha, 2014;
Hathurusingha and Davey, 2013)
The applicability of the generalized form of the model for prediction for
other aquaculture species, in particular rainbow trout (Oncorhynchus mykiss),
was assessed with independent published data by Davey and Hathurusingha
(2014). Reported predictions showed moderate-to-good agreement for both
fish species and it was concluded the model is therefore adequate for these two
species.
They concluded the model was free of programming and computational
errors. Significantly, the quantitative nature of the model suggested it could be
applied through application to automatic growth controls.
For model validation, an extensive two-year study with commercial RAS
farmed barramundi (Lates calcarifer) in which fingerlings (~ 0.01 kg) were
grown to harvest (~ 0.85 kg) at 245 days was carried out. Importantly, the
concentration of both taint chemicals in the RAS growth water was controlled
using continuous dosing of hydrogen peroxide (2.5 mg L-^1 ) as a benign
biocide. A dedicated dosing apparatus was used for this purpose
(Hathurusingha and Davey, 2016 b; Hathurusingha, 2015).