Overfishing is threatening more than 90 species in Europe with extinction. While fish farms were once tipped to help offset the effect of plummeting stocks, it turned out they can actually make matters worse.
Aquaculture, or fish farms, will soon surpass wild fisheries as the main source of seafood. In theory, they could help relieve the pressure on wild stocks, except that the food given to fish in farms, called aquafeed, is often dependent on smaller wild species, like anchovies and sardines, which, when overfished, sends shockwaves up the food chain.
‘Wild fish stocks used to be the basis of the raw material (of aquafeeds) and have gradually been replaced by plant ingredients. This effort needs to be continued so wild stocks are managed in a sustainable way and they are not exploited as aquaculture continues to increase,’ said Ivar Rønnestad, Professor in Environmental Physiology at the University of Bergen, Norway.
But staying out of our oceans might not be an option as it’s difficult to make fish without fish.
‘Fish need protein to grow and the challenge with plant protein and other alternative ingredients is that some of them have anti-nutrients while the nutrient composition and quality is not fully sufficient for growth,’ said Prof. Rønnestad, who is also the coordinator of WISEFEED, an EU-funded project looking to improve the sustainability of aquafeeds.
To solve this, the project, which started this year, will examine the metabolism of farmed fish and develop an aquafeed that combines plant and marine ingredients in order to get the most efficient growth while lowering aquaculture’s dependency on wild fish.
‘Sustainability will be balanced between increasing demand and limited resources,’ said Prof. Rønnestad.
To find the most sustainable feed for a variety of species they are carrying out dietary experiments in Portugal, Spain and Vietnam.