The following article by IFFO Neil Auchterlonie was written for Aquafeed International.

Introduction

It is stating the obvious to say that the use of fishmeal and fish oil in aquafeeds has changed over time.  With high inclusion rates of fishmeal and fish oil common in early modern aquafeeds, and especially those for salmonids, these materials could be regarded as the foundation of fed aquaculture as we know it (Auchterlonie, 2016).  The provision of diets that met the farmed fish nutritional needs essentially freed up the industry to develop systems technology and health controls, that made the advances in the volume of production that were required to achieve viability.  Inclusion rates seen with those early diets were 90% or more for total marine-sourced materials (Ytrestøyl, Aas, & Åsgård, 2015), and this was only feasible when the aquaculture industry was of relatively small volume.  Over time the partial substitution of marine ingredients with those of other (terrestrial, mainly vegetable but some animal proteins) origin occurred to allow a continuing supply of feed to aquaculture within a global market.  The challenge was in meeting the volume of supply required for the developing aquaculture industry. 

There is an economic consideration too, that emanates from the volume of supply point.  Although marine ingredients may appear as higher cost compared to the alternatives in the market, it is simplistic to look at feed ingredients from solely that perspective as bioeconomic models have a great deal more complexity, and feed formulations are not all about price – the performance of the material needs to be taken into account.  This has already been shown with fishmeal in respect of feeds for weaning piglets (Ma et al., 2013) where the growth and health advantages of high quality fishmeal in those feeds provide benefits that extend across the whole production cycle.  The same may well be true for fish species.  (Interestingly, it is the comparative cost of marine ingredients that provides the financial attraction from the investment sector that supports the development of alternatives, as discussed in Naylor et al. (2009) who describe the situation thus: “price signals will provide the best inducement for technological and management change”, even if – nutritionally - those alternatives are generally quite different to fishmeal and fish oil.)

Aquaculture is the most successful protein sector in recent times, and – generally - is an efficient way of producing protein for humanity largely as a result of growing cold-blooded animals in an environment that supports their body weight.  Aquaculture development has been dramatic and now accounts for 44.1% of total seafood production (Food and Agriculture Organisation, 2016).  This development will continue and forecasts for growth remain high even though the rate of growth has slowed from 7.2% over 1995-2004, to 5.8% from 2005 to 2014.  Regions or countries are developing aquaculture strategies, within often sit growth targets, and although fed aquaculture is only part of the total figure (FAO estimates this at 69.2%, some of which will also be extensive production[1]), it is clear that there will be a continuing demand for increasing aquafeed volume for some time to come.  Alternative proteins and oils have been suggested for many years and other than the obvious replacements that have already occurred with vegetable-based ingredients, for the most part the commercial reality for many of the alternatives still seems some way off.  At the current time, the key issue for supporting aquaculture development is to continue to make the best use of the fishmeal and fish oil resource we have.

Fisheries supplying fishmeal

In a normal year global supply of fishmeal is in the region of 5 million tonnes, with an additional 1 million tonnes, or just under, of fish oil.  Annual variation occurs due to the fluctuations of supply around the main fisheries which provide the raw material for the fishmeal production process, the most important of which is that of the Peruvian anchovy (Engraulis ringens).  Environmental fluctuations can have an impact on stock levels, where changes in current speed, direction and water temperature may affect primary production and the timing and matching of larval fish with prey items, consequently affecting recruitment into the fishery.  It has been widely accepted for years that El Niňo events have an impact on the productivity of the South Pacific Ocean (Schreiber, Ñiquen, & Bouchon, 2011), and these can markedly affect the biomass of the Peruvian anchovy, a stock which contributes somewhere between 15-20% of raw material supply for fishmeal and fish oil manufacture.

The Peruvian anchovy is an excellent example of a small pelagic fish species of the type that provides the majority of the whole fish for fishmeal and fish oil production.  Small pelagic fish (SPF), also known as forage fish, comprise approximately 22% of global annual catch according to the FAO[2].  Examples of these SPF species are the anchovies, sardines, pilchards, herrings, capelin and menhaden, also known as Low Trophic Level fisheries on account of the position they hold within the ecosystem.  Stocks can show a high variability linked to environmental factors including the vulnerability of planktonic early life-stages and their recruitment (Ospina-Alvarez et al., 2013), but in general are more readily modelled and managed than many of the food species fisheries.  Typically, these are single-species stocks that mature early, and have high fecundity, so when the environmental conditions are optimal they can reach very high abundance levels.

The management of SPF fisheries has been at the centre of some controversy in recent years.  A scientific report published in 2013, commissioned by the Lenfest Ocean Program, “Little Fish, Big Impact” suggested a precautionary approach to the management of SPF stocks to allow for the needs of piscine, avian and mammalian predators in the ecosystem.  This work was based on the use of ecosystem models that had previously been used in the terrestrial environment.  There is now some scientific debate about whether the methodology in the report is valid, and other authors have recently challenged the assumptions of the original work (Hilborn, 2017).  The more recent science suggests that there is “little evidence for a strong connection between forage fish abundance and the rate of change in abundance of their predators”.  It seems that environmental factors, rather than fishing pressure, are the dominant factor in abundance, and we may expect continuing scientific effort on the subject which will hopefully improve the predictability of stock management.  That predictability should remove some of the uncertainty in stock modelling and management.  Providing additional evidence that tackles a general precautionary approach, improves the accuracy of TAC and quota setting, which in turn has the potential to improve the productivity of the SPF fisheries.  That improved productivity of SPF fisheries subsequently supports protein supply and the global food security agenda.

SPF fisheries are therefore, on the whole, comparatively easier to manage than mixed stock (food) fisheries.  In this respect, there has been a strong adoption of certification in the fishmeal industry, to the extent that over 45% of global supply is independently accredited to the IFFO Responsible Supply standard[3].  The trend is continuing upwards as this proportion is increasing year on year with interest from new fisheries and the adoption of IFFO RS Improvers Programme (IP) projects and other Fisheries Improvement Project (FIPs).  Also noteworthy is the ability of SPF stocks to recover from low population levels which often result from environmental variability.  They are very resilient to the environmental factors that may cause such fluctuations, and this point is never better illustrated than in the ability of the Peruvian anchovy to recover from low stock levels seen during El Niňo events[4].  For a variety of different reasons, these stocks have only very limited, or no, direct human consumption markets so, despite the criticisms of some authors (e.g. Cashion, Le Manach, Zeller, & Pauly, 2017) about a direct consumption loss they may very likely make much more of a contribution to global protein supply as feed materials for food products that have a real market demand.

 

Increasing raw material supply from byproduct

The world’s global supply of fishmeal is not produced solely from fisheries though, and there is another segment that contributes a smaller but important volume.  A significant, and increasing proportion of annual supply now comes from the processing of seafood byproduct, where frames, heads, viscera and other trimmings are used to produce marine ingredients.  The FAO estimates that somewhere between 25% and 35% of global fishmeal supply comes from this material at the current time (Food and Agriculture Organisation, 2016), and that is clearly an efficient use of material for which other uses are relatively restricted.  An IFFO-funded project, reporting in 2016, suggests that there is a significant volume of byproduct raw material that at this stage is uncollected and therefore not utilised (and very likely going into waste streams).  Current estimates are that globally another 11.7 million tonnes of raw material is available, equating to another 2.365 million tonnes of fishmeal and 352,000 tonnes of fish oil if it could be collected and processed (Jackson and Newton, 2016).  With the growth in aquaculture having the potential to supply even more byproduct material, this could actually increase through to 2025, to a volume of 45 million tonnes available raw material from the current total of 35 million tonnes potential (In fact, something like 20-22 million tonnes is processed into fishmeal and fish oil every year).

 

Fishmeal – more than just protein

This volume is a comparatively limited supply of fishmeal into aquafeed (as an example, 348 million tonnes of soya bean is the USDA’s estimate[5] for production over the period between June 2017 and June 2018; soybean meal accounts for 35%[6] of the weight of raw soybean, which equates to 121.8 million tonnes; therefore, the volume of fishmeal produced equates to 4.1% of total soya volume).  It is a low volume, but high value ingredient, with a price that reflects the nutritional importance of the material in feed formulations.  Although fishmeal is a high protein (60-72%) ingredient, its value comes not just in the provision of protein as a macronutrient for growth (although it is important for that based on high digestibility figures).  Fishmeal has an excellent amino acid balance, obviously reflecting directly the amino acid balance in fish, and therefore very similar to the needs of carnivorous species which have evolved over millenia to utilise proteins with amino acids found in these proportions.  It is therefore not surprising that it meets the nutritional requirements of carnivorous species directly.

It is not, however, merely the amino acid balance in fishmeal that is of benefit to farmed fish species.  Fishmeal is exceedingly rich in some of the minerals and vitamins that are known to be essential for fish nutrition and health.  Many of the vegetable-based competitor ingredients from terrestrial systems do not contain these compounds at the same levels, largely because they reflect a plant’s (and consuming animal’s) physiological needs in the terrestrial environment.  Those requirements are different, and that is a function of evolutionary biology.  Other aspects of the vegetable-based material include the presence of substances known as anti-nutritional factors (ANFs), again a reflection of plants operating in an environment where they were at risk of being consumed by herbivores – those compounds being a protection against being eaten.  Plants also contain fibre, carbohydrate and other compounds which cannot be utilised by many carnivorous species.  This results in the use of processed and concentrated material, such as soy protein concentrate SPC, with the processing of the raw material carrying an additional energy cost (and diets made predominantly with this type of material may also require specific amino acid supplementation in formulations for an individual farmed fish species).

The nutritional quality of fishmeal has been known for many years and its richness as a source of vitamins and minerals, and their nutritional role for farmed animals well documented (Windsor and Barlow, 1981).  Fishmeal is rich in vitamins such as the B-group vitamins, especially choline and niacin, and it is also rich in various minerals important for farmed animal health including calcium, phosphorus, and also selenium.  These micronutrients are not only important for the physiology and health of farmed animals, but are important nutritionally for the consumer as well.  Fish oil, also, is usually present in fishmeal, in the polyunsaturated form and with global supplies being limited this contribution is accounted for in feed formulations.  Often rich in the omega-3 fatty acids eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), the levels are variable depending on the source species (Cho & Kim, 2011).  At an overall fat level of 8-12% in a standard product, fishmeal is a rich source of these materials (Windsor and Barlow, 1981), and the contribution from fishmeal is a significant proportion of the supply into aquafeeds. 

Fish Oil – benefits for farmed fish as well as the consumer

There are a whole host of scientific publications on the benefits of fish oil to human physiology, with a range of level of effects and outcomes cited for a wide variety of conditions[7].  We also know that although some freshwater fish species are capable of “bioconverting” shorter chain fatty acids into the longer chain EPA and DHA omega-3 fatty acids (Turchini, Torstensen, & Ng, 2009), they are essential nutrients for marine fish species (Sargent et al., 1999), including salmon.  There is therefore a strict nutritional need to provide these materials into salmon and other feeds.  With fish oil only being the available source that currently meets the volume requirement, the drawdown is reflected in the IFFO annual statistics which indicated that in 2015 73% of global fish oil apparent usage (total 916,000 tonnes) was directed to aquaculture, and 58% of that fraction was taken by salmonid feed.  Naylor et al. (2009) discussed the supply of fishmeal and fish oil into aquafeeds to meet the demand of a developing industry, and concluded that although there is pressure on both materials it is that for fish oil which drives the pressure on raw material availability.  We are seeing in some instances, and especially with farmed Atlantic salmon that the omega-3 content of the fillets reaching the market is reducing as a consequence of lowering inclusion rates in feed (Sprague, Dick, & Tocher, 2016).  That is for salmon produced on standard feeds, and it does leave the pathway open to those producers who may wish to diversify into premium products with higher EPA and DHA concentrations.

 

How feed tastes to the animal, and its relevance to production

An important but often overlooked factor in the development of aquafeeds is the palatability of the pelleted feed to the farmed fish.  This is an essential factor in appetence and feed intake volume, and therefore has an effect on overall fish growth and production.  It can also be of primary importance in key juvenile stages where there may only be a short window of time to get juvenile fish onto feed.  Fishmeal is recognised as being important in farmed animal nutrition and production of pigs (Dong & Pluske, 2007) and poultry (Karimi, 2006) in the juvenile stages, where it has been successfully used on a strategic basis to get the younger animals onto extraneous feed.  In those industries the use of fishmeal to improve production efficiency in younger animals makes economic sense (Ma et al., 2013), despite the higher cost of the ingredient when compared to other available feed constituents. 

In fish, similar effects have been observed.  (Enes & Peres, 2015) describes this concept and (B. Glencross, N. Rutherford, 2011) suggested a threshold for fishmeal in feeds for barramundi of 15% to avoid any problems linked to inappetence.  Some other species such as gilthead sea bream have shown similar responses (Kissil, Lupatsch, Higgs, & Hardy, 2000), but in some trials other species such as Pacific white shrimp (Samocha, Davis, Saoud, & Debault, 2004) and Atlantic salmon (Refstie, S., Storebakken & Roem, 1998) have not shown the same response.  It appears that this is a topic that requires further investigation, although it is quite clear that fishmeal with the presence of numerous different compounds including some volatile organic compounds has at least the potential to be an attractant and improve palatability.  The non-essential amino acid, glutamic acid, has been identified as one of the compounds that supports fishmeal palatability for aquafeeds (Miles & Chapman, 2015).

 

Summary

It is clear that the contribution that fishmeal and fish oil has made to global aquafeed has been substantial and, in the past, has certainly provided the foundation for modern fed aquaculture production systems.  In real terms, the successful aquaculture industry we have today would not have occurred without the contribution these materials made to aquafeed.  Contemporary systems have changed, however, and with the onus on feed supply more about achieving volumes, the use of marine ingredients is shifting to points in the production process where their nutritional advantages may be best utilised.  The benefits of marine ingredients go well beyond the provision of crude protein and fat for farmed fish diets and the range of micronutrients found in the materials is important for production, for health, and for the quality of the end product in fed aquaculture.  As a strategically important ingredient already increased proportions of fishmeal and fish oil are seen in juvenile feeds compared with grower diets, and these materials also have a contribution to make to broodstock diets along with the implications that has for the successive generation.

 

References

Auchterlonie, N. (2016) Marine ingredients as a foundation for global fed aquaculture production.  Aquafeed International, November 2016, 30-33.

B. Glencross, N. Rutherford, & B. J. (2011). Evaluating options for fishmeal replacement in diets for juvenile barramundi (Lates calcarifer). Aquaculture Nutrition, 17, 722–732. http://doi.org/10.1111/j.1365-2095.2010.00834.x

Cashion, T., Le Manach, F., Zeller, D., & Pauly, D. (2017). Most fish destined for fishmeal production are food- ­ grade fish. Fish and Fisheries, 0, 1–8. http://doi.org/10.1111/faf.12209

Cho, J. H., & Kim, I. H. (2011). Fish meal – nutritive value. Journal of Animal Physiology and Animal Nutrition, 95, 685–692. http://doi.org/10.1111/j.1439-0396.2010.01109.x

Dong, G. Z., & Pluske, J. R. (2007). The Low Feed Intake in Newly-weaned Pigs : Problems and Possible Solutions. Asian-Aust. J. Anim. Sci., 20(3), 440–452.

Enes, P., & Peres, H. (2015). 8 - Replacing fishmeal and fish oil in industrial aquafeeds for carnivorous fish. Feed and Feeding Practices in Aquaculture. Elsevier Ltd. http://doi.org/10.1016/B978-0-08-100506-4.00008-8

Food and Agriculture Organisation. (2016). The State of World Fisheries and Aquaculture 2016.

Karimi, A. (2006). The Effects of Varying Fishmeal Inclusion Levels (%) on Performance of Broiler Chicks. International Journal of Poultry Science, 5(3), 255–258.

Kissil, G. W., Lupatsch, I., Higgs, D. A., & Hardy, R. W. (2000). Dietary substitution of soy and rapeseed protein concentrates for fish meal , and their effects on growth and nutrient utilization in gilthead seabream Sparus aurata L .

Ma, Q., Liu, G., Jian, Y., Ma, G., Chen, L., Chen, J., … Ji, C. (2013). Effects of different quality fishmeal and other protein sources on growth performance of weaned piglets. IFFO Tehnical Report, 1–15.

Miles, R. D., & Chapman, F. A. (2015). The Benefits of Fish Meal in Aquaculture Diets 1 Benefits of Fishmeal Incorporated into Fish Diets.

Naylor, R. L., Hardy, R. W., Bureau, D. P., Chiu, A., Elliott, M., Farrell, A. P., … Nichols, P. D. (2009). Feeding aquaculture in an era of finite resources. PNAS, 106(36), 15103–15110. http://doi.org/10.1073/pnas.0905235106

Ospina-Alvarez, A., Bernal, M., Catalan, I. A., Roos, D., Bigot, J., & Palomera, I. (2013). Modeling Fish Egg Production and Spatial Distribution from Acoustic Data : A Step Forward into the Analysis of Recruitment. PLOS One, 8(9), 1–18. http://doi.org/10.1371/journal.pone.0073687

Refstie, S., Storebakken, T., & Roem, A. J. (1998). Feed consumption and conversion in Atlantic salmon ž Salmo salar / fed diets with fish meal , extracted soybean meal or soybean meal with reduced content of oligosaccharides , trypsin inhibitors , lectins and soya antigens. Aquaculture, (1), 301–312.

Samocha, T. M., Davis, D. A., Saoud, I. P., & Debault, K. (2004). Substitution of fish meal by co-extruded soybean poultry by-product meal in practical diets for the Pacific white shrimp , Litopenaeus vannamei, 231, 197–203. http://doi.org/10.1016/j.aquaculture.2003.08.023

Sargent, J., Mcevoy, L., Estevez, A., Bell, G., Bell, M., Henderson, J., & Tocher, D. (1999). Lipid nutrition of marine fish during early development : current status and future directions, 217–229.

Schreiber, M. A., Ñiquen, M., & Bouchon, M. (2011). Coping strategies to deal with environmental variability and extreme climatic events the Peruvian anchovy fishery. Sustainability, 3(6), 823–846. http://doi.org/10.3390/su3060823

Sprague, M., Dick, J. R., & Tocher, D. R. (2016). Impact of sustainable feeds on omega-3 long-chain fatty acid levels in farmed Atlantic salmon , 2006 – 2015. Nature Publishing Group, (November 2015), 1–9. http://doi.org/10.1038/srep21892

Turchini, G. M., Torstensen, B. E., & Ng, W. (2009). Fish oil replacement in finfish nutrition, 10–57. http://doi.org/10.1111/j.1753-5131.2008.01001.x

Ytrestøyl, T., Aas, T. S., & Åsgård, T. (2015). Utilisation of feed resources in production of Atlantic salmon (Salmo salar) in Norway. Aquaculture, 448, 365–374. http://doi.org/10.1016/j.aquaculture.2015.06.023