Appendix 15 – Methods for Calculating Feed Efficiency

This Appendix details the methods to calculate the metrics on feed efficiency required by Indicator 2.12.5: economic Feed Conversion Ratio (eFCR), Forage Fish Dependency Ratio (FFDR), and EPA and DHA content in feed and as percentage of fish oil in feed.

Calculations can be made using the calculation templates provided by ASC.

15.1 – economic Feed Conversion Ratio (eFCR)

The economic Feed Conversion Ratio (eFCR) is the ratio between the amount of feed used and the weight of animals produced, taking into account uneaten feed and loss of animals during production, such as mortality or escapes. The eFCR is calculated according to Aas et al. (2019) 159159Aas, T.S., Ytrestøl, T. & Åsgård, T. (2019). Utilization of feed resources in the production of Atlantic salmon (Salmo salar) in Norway: An update for 2016. Aquaculture Reports 15. https://doi.org/10.1016/j.aqrep.2019.100216 as follows:

$\mathrm{eFCR}=\frac{\text{total feed use}\left(\mathrm{tonnes}\right)}{\text{net production}\left(\mathrm{tonnes}\right)}$

$\text{net production}\left(\mathrm{tonnes}\right)=\mathrm{harvested}\mathrm{production}\left(\mathrm{tonnes}\right)-\mathrm{stocked}\mathrm{production}\left(\mathrm{tonnes}\right)$

15.2 – Forage Fish Dependency Ratio (FFDR)

The Forage Fish Dependency Ratio (FFDR) measures the amount of forage fish in fishmeal (FFDRm) and fish oil (FFDRo) used to produce one kg of farmed animal.

The ratio considers the differences in content and yield between the feed types used. FFDRm and FFDRo are calculated according to Aas et al. (2019)159159Aas, T.S., Ytrestøl, T. & Åsgård, T. (2019). Utilization of feed resources in the production of Atlantic salmon (Salmo salar) in Norway: An update for 2016. Aquaculture Reports 15. https://doi.org/10.1016/j.aqrep.2019.100216:

$\mathrm{FFD}{R}_m=\frac{(\frac{f{\text{m content}}_{\mathrm{type}1}(\%)}{{\text{fm yield}}_{\mathrm{type}1}(\%)}*{\text{feed use}}_{\mathrm{type}1}(\mathrm{tonnes}\left)\right)+(\frac{f{\text{m content}}_{\mathrm{type}2}(\%)}{{\text{fm yield}}_{\mathrm{type}2}(\%)}*{\text{feed use}}_{\mathrm{type}2}(\mathrm{tonnes}\left)\right)+\mathrm{etc}}{\text{total feed use}\left(\mathrm{tonnes}\right)}*\mathrm{eFCR}$

$\mathrm{FFD}{R}_o=\frac{(\frac{f{\text{o content}}_{\mathrm{type}1}(\%)}{{\text{fo yield}}_{\mathrm{type}1}(\%)}*{\text{feed use}}_{\mathrm{type}1}(\mathrm{tonnes}\left)\right)+(\frac{{\text{fo content}}_{\mathrm{type}2}(\%)}{{\text{fo yield}}_{\mathrm{type}2}(\%)}*{\text{feed use}}_{\mathrm{type}2}(\mathrm{tonnes}\left)\right)+\mathrm{etc}}{\text{total feed use}\left(\mathrm{tonnes}\right)}*\mathrm{eFCR}$

fm content (%) and fo content (%) are the fishmeal or fish oil content of each feed type respectivelyfo yield (%) and fm yield (%) are the efficiencies at which fish oil or meal are derived for each feed type a (note that yield is equal to fishmeal production (tonnes)/fish landings (tonnes) * 100). ASC-certified farms receive this information from the ASC-certified feed mill.

Only fishmeal and fish oil derived directly from forage fisheries (e.g. anchoveta) is to be included in the calculation of FFDR.

Fishmeal and fish oil derived from fisheries’ by-products, such as trimmings and offal, shall not be included in the calculation of FFDR. Trimmings are defined as by-products when fish are processed for human consumption or if whole fish is rejected for use in human consumption.

15.3 – EPA and DHA content in feed (marine salmonids)

The EPA and DHA content in feed is calculated per site as follows:

$\text{EPA and DHA in feed}(g/\mathrm{kg})=\frac{\text{fo content}(\%)*\text{EPA and DHA content}(\%)}{10}$

$\text{weighted EPA and DHA in feed}(g/\mathrm{kg})=\frac{\text{total EPA and DHA in feed}\left(g\right)}{\text{total feed use}\left(\mathrm{tonnes}\right)*1000}$

Total EPA and DHA in feed are calculated as follows:

$\text{total EPA and DHA in feed}\left(g\right)=\left({\text{EPA and DHA content}}_{\mathrm{type}1}\right(\%)*{\text{fo content}}_{\mathrm{type}1}(\%)*{\text{feed use}}_{\mathrm{type}1}(\mathrm{tonnes})*100)+\left({\text{EPA and DHA content}}_{\mathrm{type}2}\right(\%)*{\text{fo content}}_{\mathrm{type}2}(\%)*{\text{feed use}}_{\mathrm{type}2}(\mathrm{tonnes})*100)+\mathrm{etc}.$

Only fish oil derived directly from a forage fishery (e.g. anchoveta) is to be included in the calculation of EPA and DHA.

Fish oil derived from fisheries’ by-products, such as trimmings and offal, shall not be included in the calculation of EPA and DHA. Trimmings are defined as by-products when fish are processed for human consumption or if whole fish is rejected for use in human consumption.

15.4 – EPA and DHA Content as percentage of fish oil in feed (freshwater salmonids)

The EPA and DHA content as percentage of fish oil in feed is calculated per site as follows:

$\text{weighted EPA and DHA in fish oil}(\%)=$

$\frac{\left({\text{EPA and DHA content}}_{\mathrm{type}1}\right(\%)*{\text{feed use}}_{\mathrm{type}1}(\mathrm{tonnes}\left)\right)+\left({\text{EPA and DHA content}}_{\mathrm{type}2}\right(\%)*{\text{feed use}}_{\mathrm{type}2}(\mathrm{tonnes}\left)\right)+\mathrm{etc}.}{\text{total feed use}\left(\mathrm{tonnes}\right)}$

Where EPA and DHA content (%) is the feed-specific percentage of EPA and DHA content of the fish oil.

Only fish oil derived directly from a forage fishery (e.g. anchoveta) is to be included in the calculation of EPA and DHA.

Fish oil derived from fisheries’ by-products, such as trimmings and offal, shall not be included in the calculation of EPA and DHA. Trimmings are defined as by-products when fish are processed for human consumption or if whole fish is rejected for use in human consumption.