MGSA Science & Research Working Group - Aquaculture Science & Research Strategy

1) Replacement of marine resources within aquaculture diets & improved utilization of fish by-products as fishmeal ^[1-16] .

Developing suitable and sustainable alternative sources of lipid & n-3 long chain polyunsaturated fatty acids (n-3 LC PUFA) e.g. oils & PUFA from cultured microalgae ^{[1-6], [15],[ 16]}. In the medium to long-term, and in view of recent developments in Canada and USA, the UK salmon industry may well need to re-assess its position concerning de novo production of n-3 LC PUFA from GM oilseed crops.

Finding suitable & sustainable alternative sources of protein for fish feed and better fish by-product utilization ^[7-16] . The salmon industry already uses or is developing a range of protein alternatives. Fish meals have 60-70% protein content but plant-based alternatives range from 8.5-64% protein for corn & soybean concentrate, respectively. Many of these products are already used in aquafeeds but novel concentrates are required that blend different plant-based products & significantly increase protein levels to 50-60%. A number of such products are available, though most are not produced inside the UK. The EU's recent reauthorization of non-ruminant processed animal protein ( PAPs) within fish feeds is also pertinent here, as is the option of using GM soya as a protein source.

Optimizing minerals, micronutrients & essential amino acid bioavailability in alternative diets and reducing plant-origin anti-nutritional effects ^[1] . Using fish meal/oil in salmon diets helped provide balanced amino acid & fatty acid profiles & contributed to dietary vitamin & mineral content, so their replacement with vegetable-origin ingredients requires more exact knowledge of nutrient requirements. We must re-assess mineral requirements focussing on retention, growth & health of farmed fish and consumer expectations of quality. Trace element nutrition must be re-examined especially for selenium and zinc as well as other minerals.

Investigating effects of alternative diets on long-term fish health, ideally by monitoring over whole life-cycle (rather than usual 3-6 month trials) or by developing alternative evaluation methods.

Ensuring organoleptic appeal and consumer health benefits are maintained in salmon fed diets with plant/alternative-origin ingredients.

Developing alternative sources of lipids, n-3 LC PUFA and proteins is a pre-requisite to providing the increased volume of sustainable finfish feed needed to meet 2020 targets.

Necessary to improve production efficiency and feed conversion ratios of alternative feeds; supply satisfactory levels of essential nutrients to maintain the long-term health of cultured fish; maintain protein and phosphorus retention and reduce faecal waste.

Need to increase farmed salmon sales and attract more consumers, so it is vital that salmon fed with plant or alternative-origin ingredients retain their appealing organoleptic properties and human health promoting characteristics, especially in terms of n-3 LC PUFA content. Will help find satisfactory balance between health benefits to consumers, health & welfare of farmed fish, environmental impact, growth performance, efficiency and economic cost.

Few options for undertaking large-scale, replicated feeding trials. There's a clear and urgent need to provide one/more pen-based marine ongrowing facilities similar to the existing trials site at Ardnish. Without this, the industry will struggle to test raw materials or develop new diets.

HIGH PRIORITY

Currently reasonable choice of traditional and new raw materials to provide protein, energy and oil requirements for salmon culture but there are concerns about maintaining & increasing future supplies, particularly of fish oils and n-3 LC PUFA, and availability of locally-produced plant protein concentrates.

MEDIUM-HIGH PRIORITY

Need more species-specific information regarding losses, logistics & economics of utilizing by-products in different locations ^[14] .

MEDIUM-PRIORITY

2) Human health benefits of eating farmed fish, shellfish and marine vegetables. (cross- reference to remits of the Marketing Task Group and the Fish & Shellfish Hygiene Task Group).

Integrated strategy of research/education/marketing concerning the health benefits of eating farmed fish (especially salmonids), shellfish and macroalgae and should encompass less well-known benefits such as selenium and zinc intake.

MEDIUM-HIGH PRIORITY

Developing on-site, real-time monitoring of algal toxin levels ^[18] . to support statutory shellfish bioassays would reduce risks and adverse publicity from HAB-affected shellfish consumption and costs to farmer of recalling/destroying affected sales. Providing routine shellfish samples for centralised bioassays is very costly and sampling logistics restricts weekly numbers of shellfish harvested - if real-time monitored risks could dictate the obligatory sample number per site, sampling costs at low-risk sites could reduce.

MEDIUM PRIORITY

Early-warning forecasts for harmful algal blooms ( HAB) ^{[19], [20]}.

MEDIUM PRIORITY

Increasing capacity of the Scottish aquaculture industry by expanding markets (especially the domestic market) while improving the nation's health.

Increasing capacity of the Scottish aquaculture industry by expanding markets and improving public perception, safety and acceptance of its products.

Generally poor 'outreach' facilities for schools & public. Recent SEAFOOD IN SCHOOLS ^[17] . initiative valuable but short-term - needs to be extended and allocated more resources.

Requires a lot of foundation work and tests to be undertaken, and therefore this is currently a long-term goal.

Long-term funding of ASIMUTH ^{[19], [20]} HAB early forecast system to be trialled this year.

3) Specialized feeds for recirculation aquaculture systems ( RAS) ^{[21], [22]}.

Develop feeds with low faecal-waste, suitable for use within RAS, which optimize the performance of the cultured species and also that of the mechanical and bio-filters in order to generate optimal physical and chemical water parameters. Investigate feeds with higher protein digestibility, lower oil levels and careful ingredient selection.

MEDIUM PRIORITY

Increasing trend towards RAS which can provide biosecurity; reduced environmental impact and water abstraction/discharge plus improved energy efficiency when culturing species from warmer/colder waters than ambient for Scotland.

It is important to understand the effects of scaling-up. Trial RAS diets need to be tested in an industrial or at least semi-industrial scale RAS, but there are relatively few large scale recirculation systems for running replicated trials.

4) Exploration of the metabolic interactions of dietary amino acids, soluble carbohydrates, fatty acids and lipids ^[1] .

Determine absolute and relative amino acid and fatty acid and vitamin and mineral requirements with respect to life-stage, health, growth rate and feed efficiency.

MEDIUM PRIORITY

Improved nutrition and, ultimately, output.

Few options for undertaking large-scale, replicated feed trials.

5) Wrasse weaning diets ^[23] .

Reduce wrasse weaning period and associated mortalities. Develop diets that provide complete nutrition, optimal particle properties and attractants to encourage swift transition from live prey to formulated pellets.

MEDIUM PRIORITY. Small sector, but efficient diets are vital if wrasse is to be widely used by industry for the biological control of sea-lice.

Simplify and economise wrasse production for the purpose of biological control of parasites which adversely affect salmon production and welfare.

Relatively low economic incentive for feed companies to undertake this research since only low volumes of feed required at present.

6) Immunological effects of dietary ingredients ^[1] .

Explore capacity of dietary ingredients to positively affect the immune systems of farmed fish. Investigate fish gut integrity; gut-mediated immunity and dietary effects on gut microflora and fauna.

MEDIUM PRIORITY

Supports biosecurity and stocking measures to improve health, disease resistance and output. Improve public perception and economics by reducing use of chemical therapeutants.

Few options for undertaking large-scale, replicated feeding trials, coupled with limited disease-challenge research facilities available to the industry.

7) Nutrigenomics ^[1] : studying interactions between gene function and nutrition

For example: identifying the gene(s) responsible for freshwater parr's superior ability to synthesise long chain PUFAs compared to post-smolt and adult salmon and investigating if the parr gene function could be reactivated in later salmon life stage.

Present importance: LOW PRIORITY

Future importance: POTENTIALLY HIGH PRIORITY

Making better use of nutrients - for example: reducing dietary requirements for long-chain PUFAs in marine stages of salmon.

Knowledge of gene/nutrition interactions is also beneficial for selective breeding programmes.

This topic will increase in importance in coming years. At present, still a lot of foundation work is required, so it remains a relatively long-term goal.

8) Improved organic aquaculture feeds ^{[24], [25], [26]}.

Explore new organic sources of specific ingredients, such as antioxidants to maintain ingredient quality and increase the performance of organic feeds.

LOW-MEDIUM PRIORTY since small organic sector, but vital to the organic industry.

Increase efficiency and capacity of the organic aquaculture industry and improve nutritional quality of organic feeds.

Relatively low commercial/economic incentive to undertake this work because of current small size of organic aquaculture sector.

9) Understanding and improving dietary pigment uptake and deposition in salmon flesh.

Increase biological uptake and deposition of pigments and investigate how raw materials interact. Importance: low impact in terms of meeting 2020 targets, but more important scientifically.

Increase the efficiency of pigment utilisation to help reduce dietary costs.

Few options for undertaking large-scale, replicated feed trials.

10) Live-prey substitution and delivery of water- soluble nutrients in larval feeds ^[1] .

Reduce/eliminate the need to culture live-prey diets such as Artemia and rotifers for marine larvae without creating water-fouling and digestibility issues.

LOW PRIORITY since small sector, but may increase if marine sector grows.

Simplify and economise larval nutrition in marine species such as wrasse, cod, and halibut. Improved nutrition, survival and production with reduced waste and fouling of culture water.

Research trials are often small scale. It is more difficult to maintain good tank hygiene in large, well-stocked tanks so replicated trials should be at least semi-industrial scale.