Salmon fed GM-camelina oil to raise omega-3 level
Scientists in Scotland have begun a large-scale study aimed at restoring the level of omega-3 in farmed salmon by feeding them a diet containing oil from genetically modified camelina.
Stirling University’s Institute of Aquaculture (IoA) is conducting the study at an un-named loch, in collaboration with Hertfordshire-based Rothamsted Research, which developed the GM crop by adding a gene from a type of marine algae to camelina.
The IoA has carried out previous similar studies in tanks, but this is the first time in the UK that Atlantic salmon will be fed a diet produced from GM plants over the vast majority of their farmed life.
Six 5m² cages, each containing around 150 fish, are being used. Fish in three of the cages are being given a control diet with some marine content, and those in the other three cages will receive a diet containing GM camelina oil and no marine content.
The fish are currently around 200 grams and will be grown to around 4kg. The facilities are being supplied by a fish farming company and the feed is being produced by a commercial feed manufacturer.
Plant scientist, Professor Jonathan Napier from Rothamsted Research and fish nutritionist, Professor Douglas Tocher from the IoA, have been collaborating for nearly 20 years on finding a sustainable solution to deliver novel sources of omega-3 fatty acids, important for human health.
“This is the largest feeding trial to validate the efficacy of the project. It’s extremely significant because it will demonstrate the ability to use omega-3 fish oils from plants across the whole production cycle of salmon,” explained Napier, who has long been exploring how to develop a sustainable source of omega-3 using transgenic plants.
“It’s taken a decade to develop plants able to produce the oils and be used in aquaculture,” he said.
“This GM technology shows great promise as a potential solution to help fish farming remain even more sustainable while continuing to grow as an industry.”
“The joint project allows us to culture salmon to market size in sea pens while extracting data to ensure new feeds support good growth, feed use and product quality,” said Tocher.
He said fish had been grown from 100-400g in previous studies in tanks, but the current study would allow researchers to prove the benefits of the camelina oil to fish grown to a commercial weight.
During the course of the trial, Dr Monica Betancor, a research fellow at the IoA, will play a crucial role by checking on the salmons’ health and collecting data.
“Collecting samples and analysing the data are imperative to the project. To test the performance of the fish, I’ll be measuring the weight and growth of the fish, but also looking at tissue and molecular samples comparing results of fish fed the new fish feed to salmon fed a usual diet,” said Betancor.
Doubled omega-3
Betancor is the lead author of a recently-published scientific paper detailing a 12-week trial in which a group of fish was fed a diet in which GM camelina oil was the only lipid content. Two other groups were fed a standard diet and one with non-GM camelina oil.
In the abstract to the paper, Oil from transgenic Camelina sativa containing over 25% n-3 long-chain polyunsaturated fatty acids as the major lipid source in feed for Atlantic salmon, she writes: “The results clearly indicated that the oil from transgenic camelina was highly efficient in supplying n-3 LC-PUFA providing levels double that obtained with a current commercial standard, and similar to those a decade ago prior to substantial dietary fishmeal and oil replacement.”
Omega-3 fish oils, also known as omega-3 long chain polyunsaturated fatty acids such as EPA and DHA, have been proven as beneficial to human health, reducing the risk of cardiovascular disease and other metabolic diseases such as obesity and type-2 diabetes.
No extra wild fish
These oils are credited as being crucial for optimal human nutrition, but the wild fish stocks which provide them are at maximum levels of managed sustainability.
The amount of wild fish used in salmon feed over the last decade has dropped considerably, making salmon farming more sustainable but also reducing omega-3 levels in the fish. The research aims to return levels of omega-3 fatty oils in farmed fish to levels of a decade ago.
Although the study is being carried out in Scotland, it is unlikely Scottish fish farmers, or others in Europe, would be the first to use a new feed with a GM content because of customer resistance. Chile is seen as a more likely market.
