Award details

A microbial basis for Atlantic Salmon energetics

Reference	BB/P001203/1
Principal Investigator / Supervisor	Dr Martin Llewellyn
Co-Investigators / Co-Supervisors	Dr Umer Zeeshan Ijaz, Professor Neil Metcalfe, Professor William Sloan
Institution	University of Glasgow
Department	College of Medical, Veterinary, Life Sci
Funding type	Research
Value (£)	587,860
Status	Completed
Type	Research Grant
Start date	01/04/2017
End date	01/07/2021
Duration	51 months

Abstract

Atlantic salmon are anadromous salmonids of major commercial, cultural and recreational importance, in the UK, Ireland and worldwide. Metabolism, feed conversion efficiency and growth lie at the core of salmonid aquaculture productivity and its ecological impact and sustainability. The role of gut microbiota in driving energy metabolism in vertebrates is increasingly clear, opening up new avenues to fine-tune salmon metabolism and growth. The aim of this project is to establish the microbial basis for different energetic phenotypes in Atlantic salmon. In doing so, we will establish the role of microbiota in influencing host performance and energy economy. The broad project objectives are as follows: 1)Determine the links between energetic phenotype and microbiota in the natural environment, in order to explore the full variation in both sets of traits. 2)Examine the same links in fish of different life stages but in laboratory/farm settings where food is continually available and where nutritional intake can be standardised and measured. 3)Establish the role of microbiota in driving maladaptive energetic phenotypes in farm escapes and hatchery reared fish deliberately released into the wild. 4)Establish a synthetic salmon intestinal microbiome system through which to validate the energetic profiles we find in farmed and wild fish. 5)Undertake pilot microbiome transplantation to establish the causal role of microbiota in determining the phenotype of the host. The project brings together: Irish and UK expertise in fish biology, population genetics, microbial ecology; a world class UK bio-engineering laboratory; and major industrial partners (Marine Harvest, Alltech) to open new avenues to improve fish health, nutrition and productivity. The establishment of a model Atlantic salmon gut puts in place an invaluable tool for salmon aquaculture that will boost the UK's aquaculture research capacity in the lifetime of the grant and into the future.

Summary

Production of the global salmonid aquaculture industry now exceeds 2.4 megatons per annum. Major European producers expect to expand their outputs between 30-50% over the next five years. Ambitions for expansion on this scale create major concerns around fish welfare, ecological impact and the sustainability of salmon feed components. Nutrition lies at the heart of the issue. In the wild, Atlantic salmon are specialized carnivores. In aquaculture, in a move away from the unsustainable use of wild fish protein and oil, proteins of plant origin now constitute the majority (>60%) of their diet. Associated digestive abnormalities are common. In addition, plant-based diets may affect the rate at which nutrients are absorbed and the associated growth rate of salmon, which determines how quickly they grow in marine cages. Rapid marine growth is desirable since it permits more extensive fallowing of coastal aquaculture sites, which reduces the impact of farmed fish on the marine environment (pathogen transfer, nutrient pollution). Finally, while wild fish protein can be replaced by plant protein in salmon diets, oils cannot. Key omega-3 fatty acids must be sourced from the marine environment; a significant burden on wild fisheries. Ensuring the efficient assimilation of fatty acid components from salmonid diets is of paramount importance to safeguard the sustainable exploitation of marine resources. Salmon energetic phenotypes are composites of several interlinked traits: metabolic rate, body fat content, growth, energy harvest from food, energy economy in times of starvation. These traits underpin concerns around salmon nutrition. Significant energetic variation exists in both wild and farmed salmon with multiple possible drivers - both genetic and environmental. Importantly a wealth of new data indicates a role for intestinal microbiota - the bacteria that live in the guts of all vertebrates - in determining host energy metabolism. Understanding how gut bacteria influence Atlantic salmon energetics is thus fundamental to understanding their role in nutrition. This is the principal aim of this project. To achieve this we will establish the influence of gut bacteria on the energetics of salmon living in salt and freshwater, in both wild and aquaculture settings. First, in a unique experimental river system established in Burrishoole, Mayo (Marine Institute/University College Cork, ROI) we will track introduced juvenile salmon through their freshwater lifecycle, measuring both metabolic and gut microbiome variation. This 'wild' cohort will include wild and released farmed fish to establish whether differences between gut microbiota contribute to the poor performance of farmed juveniles in the wild. Secondly, we will undertake parallel freshwater experiments in simulated aquaculture conditions in the laboratory at the University of Glasgow (UoG),UK. Finally, in association with Marine Harvest, we will carry out corresponding experiments on saltwater phase pre-adult salmon in Norway. Alongside experiments with live fish, we propose to harness bioengineering expertise at the School of Engineering, UoG and biotechnological expertise via industry partner Alltech to build an artificial salmon gut system. Via the transfer and maintenance of gut bacteria from metabolically different fish from farmed and wild settings into our gut model we aim to establish how bacterial fermentation underpins differences in energy harvest from feed. Once these 'artificial' bacterial communities are established, a final exploratory phase of the project will involve their transplantation into laboratory reared juvenile salmon to evaluate their potential impact on host metabolism. Understanding how salmon gut bacteria change energetic phenotypes will open new avenues to improve fish health, nutrition and productivity. A model Atlantic salmon gut in a world class UK bio-engineering laboratory puts in place an invaluable tool for salmon aquaculture in the UK

Impact Summary

Production of the global salmonid aquaculture industry now exceeds 2.4 megatons per annum. Major European producers (e.g. Norway, Scotland, Ireland) expect to expand their outputs between 30-50% over the next five years. Ambitions for expansion on this scale create major concerns around fish welfare, ecological impact and the sustainability of salmon feed components. Nutrition lies at the core of many of the underlying concerns. Thus, addressing knowledge gaps around salmon nutrition is crucial to ensuring the sustainable expansion of the aquaculture industry. This project addresses knowledge gaps by 1) Establishing the role of gut microbiota in driving nutritional energy harvest, nutrient assimilation, metabolic rate and growth in farmed and wild Atlantic salmon. 2) Establishing and validating an artificial salmon gut system to test novel feed additives aimed at improving sustainable aquaculture production and improving fish welfare. Impacts on fish welfare include not only improved feed formulations, but also a significant potential reduction in the number of in vivo trials necessary for feed development. The principal beneficiaries of this research are the UK and Irish economies. Combined, their aquaculture industries support >10,000 jobs directly, and many more in service economies indirectly - especially in often rural and remote communities with otherwise limited access to employment. The proposed project promises to improve the efficiency of salmon growth and nutrition. In doing so it will positively benefit the competitiveness of the UK and Irish salmonid aquaculture industries, paving the way for sustainable growth and expansion of a valuable export economy. The aquaculture industry stands to benefit significantly from this research. Recognition of this fact in the first instance is the cerca £300,000 in-kind and cash contribution committed by industrial project partners. In a recent industry-wide poll of research interest areas at a recent Scottish Aquaculture Innovation Centre workshop (http://scottishaquaculture.com/events/sustainable-aquafeed-workshop), themes linked to salmon gut microbiota, novel feeds, and sustainable use of feeds (including DHA and EPA from fish oil) were identified as the top three areas of concern and interest. Our research findings with respect to the microbial drivers of Atlantic Salmon energetics, as well as the artificial gut tool we will develop - with potential for testing novel feeds, feed additives and microbial therapies - is strongly aligned with industry needs. Ultimately, via the improved understanding of the role of microbiota in salmon energetics nutrition that this project offers, there is potential to improve the efficiency of salmon aquaculture and concomitantly: 1) reduce the impact of intensifying salmonid aquaculture on coastal ecosystems as well as 2) reduce the reliance of salmonid aquaculture on wild capture fisheries.

Committee	Research Committee B (Plants, microbes, food & sustainability)
Research Topics	Animal Health, Microbiology
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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