How It Works

EWOS COMPASS takes several important considerations into account to produce optimised feed for fish at individual sites, helping farmers achieve the best profit margins per site. It also enables EWOS to provide the optimal feed recommendation for your salmon, whatever the location or season.

  • Tank Trials

  • Economic Tools

  • EWOS Growth Index

  • Field Trials

  • Nutrients and Raw Materials

Tank Trials

EWOS COMPASS is the result of many years intensive research and development by EWOS innovation, including 115 controlled tank trials, and analysis of 10,000 data points from six different geographical locations along the coast of Norway, using salmon at different sizes throughout the production cycle.

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Tank trials key to understanding salmon performance

Extensive tank and cage trials undertaken at EWOS Innovation were key to building the performance model, which is an important part of EWOS COMPASS.  Our scientists spent four years analysing the results of of these trials, studying the body composition of the resultant salmon, and gathering information from commercial customers around the globe, in order to gain a full understanding of the different factors affecting growth and performance.

The results were fed into the COMPASS model, which predicts the performance and outcome of a feed given to fish under any given condition.  It can be used to optimise dietary macronutrient balance for scenarios including varying raw material prices, salmon prices and environmental conditions.

The study comprised seven tank trials using 43 different feeds in 154 large tanks, with three running to 4-5kg and four to 2.5kg; a total of 177 trial weeks. A further three trials using 12 different feeds were undertaken in 54 small cages, all running to 4-5kg; a total of 61 trial weeks.

A meta-analysis of 16 previous tank trials from the past 10 years using 50 different feeds was also undertaken and the results added to the  model, along with extensive data from commercial trials.

The result is a robust model that helps us design the best feeds.

  • Tank trials helped develop performance model

  • Thousands of fish tested to harvest

  • Robust data helps ensure top quality feed

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Economic Tools

EWOS' economic planning tools are developed in order to give salmon farmers the best possible service. It uses advanced optimisation technology to solve planning problems and allow farmers to maximise production and income, by reacting to changing economic drivers.

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Economic Tools Help Farmers Maximise Production

EWOS' economic planning tools use advanced optimisation technology to solve planning problems. It is used by EWOS consultants to help them advise customers how to organise stocking, harvesting and feed plans for individual farm sites, in order to maximize production and income.

A comprehensive set of data is input into our optimisation program including maximum allowable biomass (MAB) per site, geographical location, harvest size, harvest capacity, smolt availability and price, salmon price, harvesting cost, feed strategy and feed price.

Based on this data, the program calculates a complete management and feed plan that will optimise production to meet harvest and processing capacity. If conditions change over time, new data can be input and an updated plan generated.

A major benefit of EWOS' optimisation program is that it gives the salmon farmer the ability to react swiftly to changes in fish growth, market prices and licensing regulations, resulting in improved profitability.

As part of our production planning service, EWOS holds regular meetings with site operatives to ensure that salmon achieve optimum growth. Our Open/Close site procedure is particularly beneficial for farmers, and links into the ongoing monitoring programme.

  • Advanced technology helps solve planning issues

  • Complete management and feed plan

  • Optimisation helps farmers stay ahead

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EWOS Growth Index

EWOS Growth Index (EGI) is a unique index that is used to measure and monitor the biological performance of farmed fish.

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EGI monitors biological performance

EWOS Growth Index (EGI) was developed in 2000, from FarmControl data gathered in Norway. The model was the first to consider the effects of fish weight, temperature and day length on the biological performance of Atlantic salmon. Following extensive testing in the UK, Canada and Chile, EWOS scientists found that this biological performance index could be used as a first-ever global index for monitoring the growth of farmed Atlantic salmon in sea water. 

The first tool based on the EGI model was a simple Excel sheet, used only for planning. Soon after, real growth, feeding and temperature data was added, and EWOS developed their signature graphs that are a useful tool at company, area or site level.

Today, advanced tools are used to automatically check recorded biological performance data from farm management systems. This data is analysed using a planning tool called EWOS HORIZON and the resulting insights used to help ensure the best production results when using EWOS feed. 


  • EGI uses fish weight, temperature and day length

  • EGI for site or cage level

  • Compares real and planned feeding rates

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Field Trials

Field sampling is an important part of our work, and has made a significant contribution to the wealth of data needed to develop the pioneering EWOS COMPASS feed concept. Combined with decades of research and a particular focus on nutrient content, our grower feeds help farmers achieve excellent growth in their salmon.

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Field sampling shows excellent results

A large field trial was conducted at Helgeland Research Station in the North of Norway with Autumn 2012 smolts (S0) and Spring 2013 smolts (S1). At the start of the experiment, the fish had average weights of 1kg and 2kg respectively, for the S0 and S1 generations. Each generation was fed five different EWOS COMPASS optimised diets in triplicate groups, using small 5 x 5m net pens with feed collection. Preliminary data for the 2012 S0 smolts revealed an impressive average 7% increased weight gain for the best EWOS COMPASS optimised diet, compared to a standard EWOS OPAL 110 diet. Full results from the 2013 S1 generation will be available in late Autumn 2014. 

EWOS scientists are excited by the latest results, which fit in with their models confirming the potential to achieve up to 15% better growth with EWOS COMPASS optimised grower diets, throughout the whole seawater production cycle. 

The field trials also helped EWOS to learn a lot more about the optimal macronutrient formulations required for salmon feed during the winter period, and the experience is being used as part of a continuous formulation improvement process to give salmon farmers the best possible feed.

  • EWOS COMPASS helped achieve 7% growth increase

  • Scientists predict 15% better growth potential

  • Field trials benefit continuous improvement process

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Nutrients and Raw Materials

Scientists have developed a range of tools that enable EWOS to select raw materials and ensure that our feed delivers optimised nutrition

See Compass In Practice
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Tools for Optimised Nutrition

EWOS scientists have developed a number of tools to ensure that our feed provides optimised nutrition for salmon in all the markets we supply. EWOS FMTOOL is used to check various quality criteria in fishmeal, and tells us that it is digestible and able to support the growth rate required by the fish farmer.  

EWOS OILMIX model predicts the final fatty acid composition of a salmon fillet, based on a required flesh quality result at a given fish weight. The model considers factors including dietary fat level, water temperature and different oil types, and allows EWOS to prepare the correct blend of oils to give active control over fat saturation and digestibility, whilst ensuring availability of healthy marine omega-3 fatty acids.

EWOS buys soya protein concentrate (SPC) from a number of different suppliers. Because SPC can vary in composition and nutritional quality between batches and suppliers, EWOS Innovation developed a tool that is routinely used to check the quality and consistency of SPC samples and compare them to EWOS' specifications.  

The declining use of marine raw materials means that we are using more terrestrial raw materials like SPC, so it is very important to control quality and consistency to ensure optimised feed performance.

  • EWOS FMTool ensures fishmeal is top quality

  • EWOS OilMix model ensures correct oil blend

  • SPC Checker a valuable soya protein tool

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