Scientists at the University of Liverpool are developing a new plant-based product that could replace fishmeal, reducing the need for farmers to feed fish to other fish at a time when more than 90% of EU waters are at risk from overfishing.

It is estimated that in order to satisfy consumer need for fish in an expanding human population, the UK market would need to increase supplies by more than 1.9 million tonnes by 2035.

To help sustain fish stocks, the aquaculture industry is working towards replacing fishmeal with plant proteins, such as soya.  The difficulty with this approach, however, is that many plants contain anti-nutrients that prevent digestive enzymes from working, resulting in poor digestion and failure to absorb important nutrients. 

Scientists at the University of Liverpool are  leading a consortium including University of the Highlands and Islands; international feed manufacturer, Skretting; the UK’s leading supplier of farmed sea bass, Anglesey Aquaculture; and University of Nottingham based company, Eminate, to resolve this issue by fermenting plant protein sources, which will use ‘good bacteria’ to predigest food and make nutrients more available for absorption in the gut.  

Dr Iain Young, from the University’s Institute of Integrative Biology explained: “Using fishmeal means that you are feeding fish to fish.  With the increasing demand for fish, in a human population that is set to reach just over nine billion in the next 20 years, this approach will continue to deplete fish stocks.  Food based on soya and other beans has been tested as a possible replacement for fishmeal, but it contains anti-nutrients that cause difficulties with digestion and absorption of nutrients.”

Solutions to this problem include preheating the plant protein to break down the toxins and anti-nutrients, but this is a costly method to sustain.  Fermentation techniques, however, have proved cost-effective in agriculture and other industries and so the Liverpool team aim to exploit this to replace up to 15% of fishmeal, representing fish sales of approximately £14 million.

Dr Young continued: “Fermentation methods could predigest the toxins and anti-nutrients in plant protein food, making it easier for the fish to absorb and maintain overall good health.  It will help resolve current technical limitations of the product and address the concerns about overfishing and food shortage in the years to come.”