Blue Ocean Strategy, Frontier Farming of the Century
Why is aquaculture important?
Wild or captured fisheries have remained relatively static in output since late 1980s (output has remained between 80 and 90 tonnes per annum). In the same period, population has grown by a whopping 2.7 billion people[i]. Aquaculture thus needs to increase its output to feed growing population. The annual growth rate for aquaculture from 2001–2016 has been about 5.8%. In the early 2010s, aquaculture output has already exceeded output from captured fisheries. However, the growth rate of aquaculture is expected to slow due to price pressure on aquaculture inputs especially fish feed. Reversing the expected trend may be possible if there is increase investment for the application of best available technologies, implementing economies of scale, and vertical value chain integration.
Our per capita consumption of seafood produce has grown from 18.5kg in 2011, to 20.3kg in 2016. The most recent data on the global marine fish stock is troubling, and as of 2015, only 7% of the global marine fish stock is under-fished, 33% is over-fished, while 60% is maximally sustainably fished.[ii] The growth of aquaculture will:
(i) strengthen the state of the global food security;
(ii) reduce environmental burden of wild fisheries while allowing depleted stocks to recover; and
(iii) provide jobs for fishermen who lost part or all of their income from collapsing fisheries worldwide. The proportion of those employed in capture fisheries decreased from 83% in 1990 to 68% in 2016, while the proportion of those employed in aquaculture correspondingly increased from 17% to 32%.
What are the problems facing aquaculture?
(i) Fish feed
Conventional fish feed comes from fishmeal (trash fish) which also comes from wild fisheries, i.e. 12% (about 20 million tonnes) of the global output. Under-fished wild marine stock is only 7% now, thus continuously relying on fishmeal for fish feed is unsustainable. If aquaculture is too keep growing, it has to wean itself off its reliance on fishmeal and rely on sustainable fish feed alternatives, otherwise a growing aquaculture will only exacerbate environmental problems and food insecurity, rather than alleviate them.
Many small aquaculture holders do not understand nor apply best practices in feeding fish. Especially for smallholders, it is not uncommon for them that in an attempt to cut cost, they feed living fish with dead and diseased fish without further intermediate processing (e.g. conversion to insect protein, cooking). This meant that uninfected and healthy fish become dead and diseased fish too. In the short term, their attempt at cutting cost leads to long term unsustainability of aquaculture business, as it leads to a vicious cycle of high fish mortality, reduce profitability, and increase losses.
Also, many of these aquaculture businesses do not know the optimum Feed Conversion Ratio (FCR) for the fish they are cultivating. (Note: FCR is the amount of feed to be given to fish for every kg of fish cultivated. Lower FCR is preferable since feed is converted to fish protein economically and efficiently). Feeding fish in excess does not lead to increase fish growth. It just meant that a lot of the feed goes uneaten, biodegrades, ultimately reducing the water quality in aquaculture which exacerbate fish diseases and mortality. Not only that, these inputs (feeds) increase sedimentation too and smother benthic organisms (Note: benthic organisms refer to organisms that live at the bottom of the ocean floor or sea floor, such as crabs, sea cucumber, sea urchins, starfish, etc)
(ii) Inland, inshore and coastal aquaculture
Competition for space: Conventional aquaculture is facing increasing competition for space from other sectors, such as residential, marina, hospitality, and land-based livestock. This meant that the development for aquaculture is also increasingly more expensive as demand for space increases why supply of space is relatively static.
Water pollution: Fertiliser runoff from agricultural farms can create toxic algae bloom for these types of aquaculture. Algae bloom and eutrophication suffocates fish through oxygen deprivation and high concentration of toxins in algae. Poor wastewater treatment from urbanisation and/or agriculture can cause others diseases to cultured species too, ranging from chemical contamination to bacterial/viral infection.
Antibiotics: Overuse of antibiotics inherent in many inland and coastal aquaculture creates antibiotic resistant bacteria that are detrimental to human health and food security. Tackling antibiotic resistance is a high priority for WHO (World Health Organisation)[iii].
Weather dependency: Production of traditional farms can be affected by weather or disease outbreak, for example, transfer of disease from wild stock to cultured stock. These factors can cause production plan to be unprecise and overall management unstable.
Stocking density: Inappropriately high stocking density (i.e. very high number of fish reared in a single m3 of space) aggravates pollution (from excessive accumulation of fish waste) and disease outbreak.
What are some of the solutions to improved aquaculture?
(i) Optimisation of fish value chain
The growth rate of aquaculture is expected to slow due to price pressure on aquaculture inputs. One way of easing on the price pressure of aquaculture inputs is to develop an integrated localised fish value chain. Fish value chain here means covering the whole life cycle of cultured fish, from brood stock (breeding pairs mating and laying eggs), to hatchery (eggs being hatched into larvae), to nurseries (growing larvae into fry, then into fingerlings), and then finally to grow-out (when fish is grown until the required adulthood prior to harvesting). Aquaculture value chain needs to be vertically integrated but requires a lot of policy and structural support with huge capital investment. However, the operational cost in the long run will be lower, providing economic benefits to both aquaculture developers and consumers. A vertically integrated value chain reduces our reliance on more expensive imported inputs and also reduction in fish mortalities during transportation.
(ii) Recirculating Aquaculture System (RAS)
The most important parts of RAS consists of fish tank, mechanical filter, bio-filter and degasser. Best practice for tank design is to have its diameter to depth ratios between 5:1 and 10:1[iv]. Water quality can be further improved and maintained by using UV lamp. UV light can kill pathogens, bacteria, virus, fungi, and small parasite without negative side effects of chemical oxidants such as ozone. UV lamp must be fully immersed in water to maximise efficiency, otherwise there will be UV loss due to reflection if placed outside. The list of fish growth parameters that RAS is able to control include oxygen, carbon dioxide, stocking density, feeding rate, organic material, water flow, light, temperature, salinity, and pH. This allows RAS to produce seafood at higher quantity and higher quality than conventional non-RAS systems. The latter’s performance is also highly variable and dependent on weather conditions where long term forecast (beyond 5 days) cannot be accurate.
A conventional non-RAS flow through system requires 30,000 litres of new water per kilo of fish produced per year. The amount of water that RAS uses is a few orders of magnitude lesser, i.e. ranging from 300 to 3000 litres of new water per kilo of fish produced per year. Thus RAS saves a lot of more water. RAS can be differentiated into low level, intensive, and super intensive system. Pump is the limiting factor in RAS due to head loss, whereby operating costs can increase 20 to 40% at 1m pumping head and over 44 to 69% at 3m head[v]. The head loss in most intensive recirculation systems today is around 2 to 3 metres.
Table 1 Comparison of degree of recirculation at different intensities[vi]
(iii) Integrated Multi-Trophic Aquaculture (IMTA)
Integrated Multi-Trophic Aquaculture (IMTA) is a concept whereby waste from one cultured species is input for another cultured species. In a typical IMTA, it consists of fish, benthic species (e.g. bivalve, and molluscs), micro-algae and seaweed. Solid waste in the form of uneaten fish feed and fish excrement are consumed by benthic species while soluble nutrients are consumed by micro-algae and seaweed. This concept allows for at least 60% of nutrient input to reach commercial products, nearly three times more than in modern net pen farms. Having multi-species cultivation not only helps in preventing water pollution typically related to aquaculture, it also allows aquaculture farmers/holders to have much less sporadic income generation due to variations of harvest periods for each cultivated species. Multi-species cultivation also provides hedge against disease outbreak of any particular cultured species. With IMTA, it is estimated that for every kg of fish produced, an additional 3kg of bivalves and 4kg of seaweed can be produced.
(iv) Offshore aquaculture
Offshore aquaculture has several benefits that inshore, coastal, and inland aquacultures do not, one of which is that offshore type does not need to compete for space. Offshore aquaculture also typically has stronger current, thus allowing metabolic waste of fish and nutrients to be dispersed, instead of relying on energy intensive pumping typical of RAS. The cages used have to be submersible to reduce exposure to crashing waves, and anchored on the sea floor, but can move up and down the water column to reduce stress on cables.
The stronger offshore current allows for higher stocking density (higher productivity). Offshore cages are also typically far enough from the coast to be less likely to be exposed to contaminants and eutrophication. The combination stronger current and geographical distance from farmlands and civilisations thus provide a better degree of protection against fish diseases and red tides. The optimal speed of sea/ocean current should be between 0.1m/s and 0.35m/s. Below speed of 0.1m/s will lead to inadequate removal rate of nutrient and metabolic waste, while speed in excess of 0.35m/s will cause FCR to increase drastically (meaning more money spent on fish feed, and less monetary return from the harvested of fish).
What does the future holds for aquaculture?
The integration of RAS with IMTA and Offshore with IMTA are interesting prospects to be further studied. These integrations have the potential to further increase global aquaculture output at reduced resource utilisation and environmental impact. They are already being tested and studied around the world, but they have not yet been scaled. In my future articles, I would be exploring RAS-IMTA and Offshore-IMTA.
“This article was written in collaboration with Lim Hooi Ren and Dr. Daniel Mahadzir who provided some research insights”
Reference:
[i] https://ourworldindata.org/world-population-growth
[ii] http://www.fao.org/state-of-fisheries-aquaculture
[iii] https://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance
[iv] https://www.sciencedirect.com/science/article/pii/S0144860998000235
[v] https://www.sciencedirect.com/science/article/pii/S0144860917302327
