1. Importance of aquaculture in the blue revolution

Most developed countries are nearing their terrestrial agricultural output capacity. Terrestrial agriculture will be highly challenged to meet the demands for a growing human population. Food production requires an epic shift towards leveraging intrinsic competitive advantages from our aquatic environment. As such, we have now entered the blue revolution where dietary protein and essential nutrients are increasingly derived from aquatic environments. However, most traditional capture fisheries are depleted or harvested at their biological limits. As stated a half century ago by famous marine explorer and ecologist Jacques Cousteau "We must farm the sea" in order to foster strong global food security. This was reiterated in 2012 by former UN Secretary General Kofi Annan who stated "Aquaculture is crucial for supplying the world's food needs for the next 50 years". Recently, aquaculture has grown annually at 7.8%; far exceeding that of terrestrial farming systems like poultry (4.6%), pork (2.2%), dairy (1.4%), beef (1.0%) and grains (1.4%) [1]. As the appetite for seafoods outpaces what capture fisheries can supply, global farmed seafood supplies in 2009 matched wild-caught seafood and this proportion is projected to rise to 62% of all seafood supplies by 2030. This firmly secures aquaculture's position in the blue economy as the most efficient use of resources for global food production. Gentry et al. [2] reported that a small fraction of coastal ocean waters (0.015%), about the size of Lake Michigan, specifically selected for sustainable aquaculture (excluding areas that interfere with shipping lanes, ocean oil extraction or marine protected areas) is required to exceed current demand for seafood by 100-fold. For the first time in history, global aquaculture production exceeded beef production in 2011 and in 2014 farmed aquatic production was valued at \$160 billion USD (74 million metric tons [mmt]) and will exceed \$240 billion USD by 2022. Indeed, as global economist and Nobel Laureate Dr. Peter Drucker recently stated "Aquaculture, not the internet, represents the most promising investment opportunity of the 21st century".

used <1% of supply, while today aquafeeds consume 71%. Aside from very real ecological issues, this tremendous demand has had a direct and highly consequential economic result of tripling the cost of fish meals and oils. While farmed salmonids represent a marginal contribution (3%) to total global farmed seafood supplies, they consume a disproportionate amount of

The Potential for 'Next-Generation', Microalgae-Based Feed Ingredients for Salmonid…

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Farming of salmonids (e.g., salmon, trout, charr) uses feed inputs more efficiently than terrestrial animal protein production systems (e.g., beef, poultry and pork). Typical feed conversion ratio (FCR) for salmonids is 1.2 g feed g gain<sup>1</sup> compared to 1.8–6.3 g feed g gain<sup>1</sup> for livestock. This is due to higher dietary protein and energy retention efficiency in salmonid fish (23–31%) compared to terrestrial farm animals (5–21%). Also, since fish are poikilothermic and expend less energy maintaining their position in the water column, edible yields of farmed salmonids are higher (68%) than terrestrial livestock (38–52%). Salmonid farming occupies low carbon footprints and those farmed in Norway, Chile and Canada may, in fact, be the most ecologically sustainable meat products on the global food protein market. Greenhouse gas (GHG) emissions of 2.2 kg CO2 eq. kg<sup>1</sup> of edible meat produced are reported in contrast to 2.7–30.0 kg CO2 eq. kg<sup>1</sup> for chicken, pork and beef. However, it's important to note that salmonids are highly piscivorous and the industry remains greatly dependent upon global ocean resources; albeit to a far lower degree than previous decades. Most commercial salmonid feeds in 1995 contained ~53% fish meal, ~31% fish oil and ~16% alternative proteins and grains, while today most feeds contain ~27% fish meal, ~15% fish oil, ~43% alternative proteins and grains and ~15% alternative oils. In Norway, total dietary composition of wild marinebased ingredients has dropped from 90 to 30% between 1990 and 2013. Nevertheless, global demand for aquafeeds is less than 40 mmt but is expected to rise dramatically to 87 mmt which will continue to exacerbate the aquafeeds dilemma. Fish meal and fish oil obtained from reduction of wild-capture pelagic fish is beyond maximum sustainable limits, is becoming cost-prohibitive and could/should be better-used for direct human consumption. These wild populations may be even more pressured by global climate change and supplies will be insufficient to meet growing aquafeed demands and thus constrain aquaculture growth. This is particularly true in emerging economies like China where production accounts for 61% of

The aquafeeds dilemma is not new and herculean efforts were made over three decades to identify a broad range of new ingredients. This developed new commodity markets and resulted in significant industrial use of animal- and plant-based feed inputs. These include high-quality rendered animal by-products (e.g., poultry meals, hydrolyzed feather meals, meat and bone meals, blood meals, etc.) and plant-based meals and protein concentrates produced from oilseeds, grains, pulses and legumes as complete or partial replacements for fish meals. Similarly, terrestrial animal fats and plant-based oils (e.g., poultry fat, beef tallow, vegetable oils, etc.) have extensively replaced fish oil in farmed salmonid feeds. However,

these finite resources.

2.2. Industrial farming of salmonids

global aquaculture and continues to grow rapidly.

2.3. Alternative feed ingredients—microalgae?

## 2. Formulated compound aquaculture feeds

#### 2.1. The aquafeeds dilemma

Of the 74 mmt of global farmed seafood produced annually, the majority (57 mmt or 77% of total) is from finfish and crustaceans, which are considered 'fed' aquaculture species. This means they require mass-produced formulated complete feeds (aquafeeds) and the production of aquafeeds will exceed 87 mmt by 2025. As a result, modern aquaculture is a major consumer of world fish meal and fish oil supplies, which has placed an unsustainable burden on traditional capture fisheries in South Pacific, South-East Asia and North Atlantic countries. This scenario represents a dramatic shift in use of these finite marine resources during the past half century. Regarding fish meal; feeds for terrestrial animals have traditionally demanded virtually all global supplies and aquafeeds consumed <1% of supply only a few decades ago, while today aquafeeds consume a staggering 73%. The situation is the same for fish oil where in 1960 virtually all supplies were used as hardened edible fats or refined industrial oils and aquafeeds used <1% of supply, while today aquafeeds consume 71%. Aside from very real ecological issues, this tremendous demand has had a direct and highly consequential economic result of tripling the cost of fish meals and oils. While farmed salmonids represent a marginal contribution (3%) to total global farmed seafood supplies, they consume a disproportionate amount of these finite resources.

#### 2.2. Industrial farming of salmonids

1. Importance of aquaculture in the blue revolution

152 Microalgal Biotechnology

ment opportunity of the 21st century".

2.1. The aquafeeds dilemma

2. Formulated compound aquaculture feeds

Most developed countries are nearing their terrestrial agricultural output capacity. Terrestrial agriculture will be highly challenged to meet the demands for a growing human population. Food production requires an epic shift towards leveraging intrinsic competitive advantages from our aquatic environment. As such, we have now entered the blue revolution where dietary protein and essential nutrients are increasingly derived from aquatic environments. However, most traditional capture fisheries are depleted or harvested at their biological limits. As stated a half century ago by famous marine explorer and ecologist Jacques Cousteau "We must farm the sea" in order to foster strong global food security. This was reiterated in 2012 by former UN Secretary General Kofi Annan who stated "Aquaculture is crucial for supplying the world's food needs for the next 50 years". Recently, aquaculture has grown annually at 7.8%; far exceeding that of terrestrial farming systems like poultry (4.6%), pork (2.2%), dairy (1.4%), beef (1.0%) and grains (1.4%) [1]. As the appetite for seafoods outpaces what capture fisheries can supply, global farmed seafood supplies in 2009 matched wild-caught seafood and this proportion is projected to rise to 62% of all seafood supplies by 2030. This firmly secures aquaculture's position in the blue economy as the most efficient use of resources for global food production. Gentry et al. [2] reported that a small fraction of coastal ocean waters (0.015%), about the size of Lake Michigan, specifically selected for sustainable aquaculture (excluding areas that interfere with shipping lanes, ocean oil extraction or marine protected areas) is required to exceed current demand for seafood by 100-fold. For the first time in history, global aquaculture production exceeded beef production in 2011 and in 2014 farmed aquatic production was valued at \$160 billion USD (74 million metric tons [mmt]) and will exceed \$240 billion USD by 2022. Indeed, as global economist and Nobel Laureate Dr. Peter Drucker recently stated "Aquaculture, not the internet, represents the most promising invest-

Of the 74 mmt of global farmed seafood produced annually, the majority (57 mmt or 77% of total) is from finfish and crustaceans, which are considered 'fed' aquaculture species. This means they require mass-produced formulated complete feeds (aquafeeds) and the production of aquafeeds will exceed 87 mmt by 2025. As a result, modern aquaculture is a major consumer of world fish meal and fish oil supplies, which has placed an unsustainable burden on traditional capture fisheries in South Pacific, South-East Asia and North Atlantic countries. This scenario represents a dramatic shift in use of these finite marine resources during the past half century. Regarding fish meal; feeds for terrestrial animals have traditionally demanded virtually all global supplies and aquafeeds consumed <1% of supply only a few decades ago, while today aquafeeds consume a staggering 73%. The situation is the same for fish oil where in 1960 virtually all supplies were used as hardened edible fats or refined industrial oils and aquafeeds Farming of salmonids (e.g., salmon, trout, charr) uses feed inputs more efficiently than terrestrial animal protein production systems (e.g., beef, poultry and pork). Typical feed conversion ratio (FCR) for salmonids is 1.2 g feed g gain<sup>1</sup> compared to 1.8–6.3 g feed g gain<sup>1</sup> for livestock. This is due to higher dietary protein and energy retention efficiency in salmonid fish (23–31%) compared to terrestrial farm animals (5–21%). Also, since fish are poikilothermic and expend less energy maintaining their position in the water column, edible yields of farmed salmonids are higher (68%) than terrestrial livestock (38–52%). Salmonid farming occupies low carbon footprints and those farmed in Norway, Chile and Canada may, in fact, be the most ecologically sustainable meat products on the global food protein market. Greenhouse gas (GHG) emissions of 2.2 kg CO2 eq. kg<sup>1</sup> of edible meat produced are reported in contrast to 2.7–30.0 kg CO2 eq. kg<sup>1</sup> for chicken, pork and beef. However, it's important to note that salmonids are highly piscivorous and the industry remains greatly dependent upon global ocean resources; albeit to a far lower degree than previous decades. Most commercial salmonid feeds in 1995 contained ~53% fish meal, ~31% fish oil and ~16% alternative proteins and grains, while today most feeds contain ~27% fish meal, ~15% fish oil, ~43% alternative proteins and grains and ~15% alternative oils. In Norway, total dietary composition of wild marinebased ingredients has dropped from 90 to 30% between 1990 and 2013. Nevertheless, global demand for aquafeeds is less than 40 mmt but is expected to rise dramatically to 87 mmt which will continue to exacerbate the aquafeeds dilemma. Fish meal and fish oil obtained from reduction of wild-capture pelagic fish is beyond maximum sustainable limits, is becoming cost-prohibitive and could/should be better-used for direct human consumption. These wild populations may be even more pressured by global climate change and supplies will be insufficient to meet growing aquafeed demands and thus constrain aquaculture growth. This is particularly true in emerging economies like China where production accounts for 61% of global aquaculture and continues to grow rapidly.

#### 2.3. Alternative feed ingredients—microalgae?

The aquafeeds dilemma is not new and herculean efforts were made over three decades to identify a broad range of new ingredients. This developed new commodity markets and resulted in significant industrial use of animal- and plant-based feed inputs. These include high-quality rendered animal by-products (e.g., poultry meals, hydrolyzed feather meals, meat and bone meals, blood meals, etc.) and plant-based meals and protein concentrates produced from oilseeds, grains, pulses and legumes as complete or partial replacements for fish meals. Similarly, terrestrial animal fats and plant-based oils (e.g., poultry fat, beef tallow, vegetable oils, etc.) have extensively replaced fish oil in farmed salmonid feeds. However, these 'second-generation' ingredients are not without limitations. Most lack certain functional properties, palatability and nutritional profiles, and many have lower digestibility and may be limited by specific antinutritional factors (ANFs) which can impair feed intake, growth performance and fish health. Some may alter final product quality for the consumer and they are also becoming increasingly costly and ecologically unsustainable. Of critical importance is that increased use of these ingredients has forced farmed salmonid production to shift alignment to terrestrial agriculture which occupies large aerial footprints, is heavily dependent on fossil fuelbased fertilizers, chemical pesticides and freshwater irrigation. Additionally, these products are grown for our own consumption; so it is of key importance to reduce competition with human food resources for sustainable production of aquafeeds. Ecological and socioeconomic issues aside, the health benefits of consuming fatty fish like farmed salmonids have become serious concerns for human nutrition with the rising use of plant-based ingredients in salmonid feeds. Uncoupling of this scenario is desperately needed to effectively minimize environmental impacts and social inequities; however, it is not simple from technological, ecological or socioeconomic viewpoints and will require economic and political incentives from governments and substantial 'buy-in' from industry and private investors.

from aquaculture nutritionists in terms of the biochemical composition of many microalgae and it is clear that some may be promising candidates for salmonid feeds based on their supply of well-balanced amino acids, essential omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), vitamins, minerals, carotenoids and bioactive compounds. While large-scale algaculture is a commercial reality in some parts of the world (e.g., Australia, China, Germany, India, Israel, Japan, Myanmar, Taiwan, United States), the sector is dominated by a handful of species with relatively insignificant annual production: Arthrospira (3,000 t), Chlorella (2,000 t), Dunaliella (1,200 t), Nostoc (600 t), Aphanizomenon (500 t), Haematococcus (300 t), Crypthecodinium (240 t) and Schizochytrium (10 t) and estimated dry biomass price is \$8,000–300,000 USD per t. Most is presently destined for human health food markets but many producers have keen interest in penetrating the massive salmonid aquafeed sector if production tonnage can be

The Potential for 'Next-Generation', Microalgae-Based Feed Ingredients for Salmonid…

http://dx.doi.org/10.5772/intechopen.73551

155

As a cautionary note, some proponents of microalgae biotechnologies suggest that they are 'super-foods' and feeding microalgae to farmed salmonids makes perfect sense since that is what their wild counterparts would naturally consume. This thinking encourages development of lower-trophic, ecologically-sustainable salmonid feed ingredients but the notion is, unfortunately, flawed. While it's true many essential dietary nutrients for wild salmonids originate in aquatic phytoplankton (microalgae) and other single-celled organisms, they are delivered through 'indirect' passage of nutrients up the aquatic food chain and rarely via 'direct' intake; as salmonids do not actively seek to consume microalgae. The notion that wild, highly piscivorous salmonid fish derive nutrients from direct ingestion of microalgae is akin to the notion that wild, highly carnivorous lions derive nutrients from direct consumption of grass. On the contrary, higher trophic predators like salmonids evolved to rely on a progression of intermediary organisms (e.g., grazing phytoplankton, zooplankton, forage fish, etc.) to extract nutrients from complex food matrices that make up 'base-of-the-food chain' organisms (e.g., phytoplankton). This upward passage and trophic accumulation of essential nutrients, referred to as food-chain amplification, transforms them into forms that the relatively simple monogastric digestive system of salmonids can assimilate and use for productive purposes like protein synthesis, growth, tissue repair, metabolic energy and reproduction. The practical implication is that, in the absence of food-chain amplification, reliance on transformative intermediary organisms represents a nutritional barrier for direct feeding of microalgae to most monogastric animals, especially coldwater farmed salmonids. This is because their capacity to extract and utilize microalgal nutrients directly is limited by the highly recalcitrant cell walls of most microalgae, combined with the relatively short gastric (acidic) digestion phase in salmonid fishes. Some industrial downstream processing is almost certainly required in order for nutrientrich microalgae to realize its potential as a much-needed next-generation ingredient. Like other ingredients once regarded as 'alternatives' but now established mainstream ingredients (e.g., corn, soy, wheat, canola, etc.), cost-effective processing technologies must be developed for microalgae to rupture cell walls, concentrate target nutrient levels, reduce/eliminate indigestible fibers, inactivate ANFs and increase nutrient digestibility for monogastric cold-water fish. With each processing step, nutritional value is increased but so is the cost of production and

increased and the price made more economical.

3.2. Challenges
