Altantic salmon by-products. (Image: IFFO)
Better use of by-products culd increase value of Scottish salmon industry
Friday, February 16, 2018, 00:00 (GMT + 9)
Researchers have found that by-products in Scottish salmon farming are generally well utilised, but that its total value output could be improved by 803 percent ( GBP 23.7 million), based on 2015 figures, which would add 5.5 percent value to the salmon industry.
Led by Julien Stevens, researchers from the University of Stirling’s Institute of Aquaculture and University of Massachusetts at Boston have recently published research funded by IFFO, The Marine Ingredients Organisation. The research investigated how value could be added to aquaculture through better utilisation of by-products, by maximising edible yields and better separation at the processing stage, looking at the Scottish salmon farming industry as a case study.
The research found that while the byproducts of the Scottish salmon farming industry are used and not wasted, they are often sold in mixed form to low-value markets.
The terrestrial livestock processing industry has long been able to separate by-products to maximise value and efficient utilisation, and this research sought to identify the best markets for salmon processing by-products in the same way.
For finfish, by-products usually include trimmings, skins, heads, frames (bones with attached flesh), viscera (guts) and blood. Far from being ‘waste’, marine by-products are a potentially important resource, as it is known they contain valuable nutrients such as minerals, vitamins, protein and lipid fractions which can support further processing into a range of products and markets.
By exploiting all high value by-product types (heads, frames, trimmings and belly flaps) for existing domestic and export food markets, the authors demonstrated that an increase of 803 percent ( GBP 23.7 million) could be reached in the total by-product value output for 2015, which would add 5.5 percent value to the salmon industry.
By directing 77 percent of the annual whole fish production towards human consumption, combining primary products (54 percent yield) with the maximum potential by-product food yield (~ 23 percent), 132,171 tonnes of food could be obtained.
The remaining by-products, minus blood water (4.3 percent), are then utilised in the important production of fishmeal and fish oil, and subsequently used in aquafeed for farm raised marine species. In this example, the use of that material in feed for European seabass and gilthead seabream, would result in 148,691 tonnes of total edible yield compared to the original production of 92,081 tonnes of salmon.
The authors also report that current Fish in: Fish out (FI:FO) models do not adequately take into account how finfish are utilised, and therefore, the efficiency of marine ingredients utilisation in aquafeeds.
"Current research highlights that FI:FO calculations can be significantly affected, first by the edible yield of the species and, secondly, by the way in which the various by-products are subsequently directed," said Dr. Neil Auchterlonie of IFFO.
In conclusion, lead author Julien Stevens said: “We hope this research facilitates improvements, there is a need for further infrastructure investment and policy support to incentivise resource efficiency, along with greater transparency on the current uses of by-products within the sector.”