Aquaponics as a Tool for Balancing the Growth of Agriculture Sectors
My previous post, Do We Expect Too Much from Aquaponics?, outlined some of the challenges facing the agriculture industry today, and explored the roles that soilless growing techniques play in meeting commercial production demands, and in facilitating food security in developing nations. In digging deeper into discussions related to the different applications of conventional hydroponics, recirculating or decoupled aquaponics, and bioponics, I am often asked about previous projects that might highlight particular benefits or limitations of a given technique.
In this article, using the West-African nation of Ghana as a case-study, we will look at some of the challenges that countries often face in balancing the growth of different farming sectors, such as traditional farming, inland aquaculture, and commercial fishing.
In the fall of 2014, sitting atop a concrete seawall, overlooking the Gulf of Guinea, I spent my mornings watching groups of men and women gather along Labadi beach, preparing for the long day of fishing ahead of them. Folks chat and mingle, while children poke through the tidewrack of a stoney outcropping. Brightly painted, wooden canoes, loosed of their canvas coverings, are dragged from a grassy grove of coconut palms, piled with bundles of nets and lines, and are shoved into the breaking surf.
Crewing the wooden crafts, teams of men paddle out beyond the chop, laying the down-current wing of a large seine net, positioning weights and buoys in a manner that ensures the net remains upright through the column of water, from sand to surface. Working their way slightly up the coast, they position the cod, the middle-most portion of the net, and begin the journey back toward shore, setting the up-current wing of the massive net, and laying claim to whatever creatures they have now encircled.
With the tow-lines of both wings back on shore, the group that had assembled over the past couple of hours snaps into action. Directed by horse-mounted cadence-callers, younger men and women split into two teams, digging their feet into the soft sand, they work together to haul the wing nets up the shore. Older women, some with babies wrapped tight to their backs, position sorting baskets and basins of water on the dunes between the two lines.
After a drawn-out fray of tug-of-war, the cod of the net breaks through the surf, carrying with it all manner of sea-life: crabs, octopuses, and fishes of all sizes. As the modest haul is brought onto the sandy beach, it is sorted for distribution to local markets and restaurants. Though a scene that rivals Gogh’s Siantes-Maries, the rapid growth and modernization of this traditional method of fishing, coupled with increased commercial trawling, and the practice of Saiko, has wreaked havoc on coastal ecosystems and fish populations.
Illegal, fine-meshed nets result in the overharvesting of juvenile fishes prior to spawning, higher levels of by-catch, and damage to seafloor habitats, while the persistent use of chemicals such as DDT, carbide, and dynomite, to incapacitate the fish, poisons local waterways, and increasing the rate of decline in fish populations; these chemicals also decrease the marketability of fish, and are harmful to consumers.
In 1999, marine fisheries produced almost 420,000 metric tons, according to data from the Food and Agriculture Organization (FAO), by the time I arrived in Ghana in 2014, annual production had fallen by over 50%, to roughly 200,000 metric tons. Dr. Isaac Okyere, University of Cape Coast, reports that landings of important fish species, such as sardines and jack mackerel, had fallen by over 80% compared to record highs seen just two decades ago.
While fisheries employ nearly 3 million people, 10% of the country’s population, Ghana Statistical Service (GSS) reports that in 2016, fisheries accounted for only 1.1% of Ghana’s Gross Domestic Product (GDP), down from a 2.5% contribution in 2009. Professor Wisdom Akpalu, Director of Environment and Natural Resource Research Initiative (ENRRI), University of Ghana, notes that the depletion of fish stocks due to illegal fishing methods may have carried losses of over USD$200 million between 2012 and 2017.
In addition to the aforementioned impacts of illegal fishing, many fishing villages along the western coast of Ghana experienced incessant flooding during 2014. These floods have been directly attributed to the overharvesting of mangroves from coastal stands, and the conversion of coastal forests to agricultural lands. By some estimations, over 97% of mangrove forests had been depleted of trees.
To refortify the coast against flooding and erosion, and to bolster marine ecosystems to increase fish populations, programs were enacted to replant coastal forests and estuaries. Though these projects have already resulted in decreased flooding, and increases in shrimp populations, the reclamation of farmland for replanting groves pushed farming operations inland, often onto arable land along freshwater waterways.
The close proximity of farmland to local waterways, has led to a number of concerns related to public health, and inland fish production. As described by researchers from the University for Development Studies, Ghana, run-off of agrochemicals such as pesticides, herbicides, and fertilizers, contaminate crops, and spread into water bodies. The introduction of toxic agrochemicals is compounded by the fact that farmers often wash their clothes and spraying equipment in open waterways that are used for drinking, cooking, and fish-rearing.
Pesticides, such as organochlorines, organophosphates, DDT, and HCH, some of which are prohibited from use in developed countries, are still widely used in developing nations such as Ghana, because they are inexpensive to manufacture, and reserves have been relocated from countries where their use has been regulated or banned.
Though USAID notes that Ghana is fortunate to have sufficient water sources to support its people, water samples from Volta Lake, and rivers near commercial farms in the Ashanti and Akumaden regions, were found to contain significant levels of lindane, endosulfan, DDT, and DDE. These chemicals inhibit the growth and functions of microorganisms, decreasing the overall health of the local wetlands.
In rural areas, which account for over 56% of the Ghanaian population, over-application of fertilizers, and the intensive rearing of livestock along the banks of waterways, leads to increased rates of soil erosion, elevated turbidity, and harmful levels of nutrients entering the streams and rivers. These factors can lead to eutrophication and hypoxia, which negatively impact microbial activity and the health of macro-invertebrates and fish populations.
Pollution of water from agro-industrial wastes is not limited to developing nations. Globally, as livestock production has risen from 7.3 billion units in 1970, to over 24 billion units in 2011, and global aquatic animal production surpassing 80 millions tonnes in 2020, waterways are regularly contaminated with agrochemicals, drug residues, and manure discharge.
With agricultural nitrate nitrogen being the most common chemical contaminant in groundwater, Eduardo Mansur, Director of FAO’s Land and Water Division, in a recent report from FAO, noted that “In most high-income countries and many emerging economies, agricultural pollution has overtaken contamination from settlements and industries as the main factor in degradation of inland and coastal waters.”
When I was in Ghana, I had the pleasure of working closely with the Ministry of Fisheries and Aquaculture Development (MoFAD), and the Ministry of Food and Agriculture (MoFA). While the MoFAD was working to increase fish production potential, by stabilizing aquatic habitats through the reforestation of mangroves and the planting of riparian buffer zones, MoFA was working diligently to assist farmers in maintaining crop production and decreasing the negative impacts of ag-practices on the local environment, while facing land-use pressures from reforestation efforts and the loss of arable land to residential and industrial development.
As I have seen in many developing nations, tensions often grow when working to balance the growth of aquaculture and farming sectors. While growth of commercial farming can lead to the misuse of agrochemicals and mismanagement of livestock, which directly decreases landings from fishing, and the ability to operating in-stream cage-culture or raceway fish farms, the conversion of premier farmland to wetlands and forests can push farmers onto less-ideal soil, which often increases agrochemical use. On the other hand, when countries look to rapidly grow their inland aquaculture production, using fish ponds, tank culture, or cage culture, local environments can suffer from excess production and discharge of harmful ammonia waste.
Working with teams from both the Ministry of Food and Agriculture (MoFA) and the Ministry of Fisheries and Aquaculture Development (MoFAD), under the leadership of the Honorable Sherri Ayittey, I was tasked with designing and evaluating collaborative solutions that would allow for increasing inland aquaculture production on non-arable land, while mitigating the discharge of harmful ammonia waste. This would allow MoFAD to address the country’s 50% deficit in annual fish production, without losing arable land to fish-rearing, or further stressing waterways with added cage culture operations. As Ghana already had over 1,500 small-scale pond farms, we focused on solutions that could aid in increasing the productivity of existing fish farms, or that could be deployed on new operations.
In evaluating potential technologies for implementation, the Ministry of Food and Agriculture (MoFA) was committed to strengthening the capacity of their extension officers in learning and promoting novel farming techniques, while the Ministry of Aquaculture and Fisheries Development sought to bolster the economic resilience of fish farms, by diversifying revenue streams across various agricultural sectors.
To decrease the burden placed on marine fishing, which was facing a range of ecological and industrial pressures, we focused on solutions that would allow for contained, inland fish farming, such as tank and pond culture. As was demonstrated by Kenya’s aquaculture stimulus program between 2009 and 2012, sudden booms in fish farming operations can carry a number of consequences that need to be considered: farmer training, availability of quality fish feed, breeding of fingerlings, and most critically, waste-water management, to ensure that harmful ammonia waste is properly handled.
While breeding rotations and manufacturing logistics can be established to address fishery inputs, and extension services can be developed to train farmers, properly managing aquaculture sludge waste is nuanced, and mismanagement of sludge waste can be detrimental to the productivity of the fish farms, and to local soil and waterways. The need to mitigate aquaculture waste, and the push to diversify the market offerings of fish farmers, lead us to design an aquaponic-style system that could be easily configured for off-taking waste from pond or tank cultures.
The final version of the solution was a contained, engineered wetland that cycles wastewater from the fish, digests and mineralizes the sludge material, and allows for the dense production of food-crops or nursery plants for other sectors of industrial farming. In addition to mitigating sludge waste, and allowing farmers to cultivate marketable crops, these implementations convert static-water ponds to pseudo-recirculating aquaculture systems, increasing water quality and dissolved oxygen levels. Given the stable production potential of soilless farming techniques, and the water-efficiency of recirculating aquaponic systems, this solution met the goals of the Ghana National Climate Change Adaptation Strategy: to “promote farming technologies that enhance productivity of agricultural lands,” and to better manage water resources.
When discussing the application of soilless technologies to address commercial and environmental pressures, this project serves to highlight two of my favorite aspects of ag-solution master-planning: interdisciplinary collaboration, and versatility of design. Collaboration between government organizations led to the development of plantable digesters that can be used to increase the production potential of existing fish farms, and can facilitate the development of inland fisheries on non-arable land, leaving arable land available for conventional farming practices. These techniques help the Ministry of Fisheries and Aquaculture Development increase fish production, while supporting the Ministry of Food and Agriculture in producing food-crops and nursery stocks for other sectors.
As it relates to versatility of design, although the massive systems engineered for this project can be classified as aquaponics, they lack many of the common identifiers associated with commercial aquaponic systems; there are no poly-tanks, intricate plumbing arrays, clean-lined growing equipment, or CEA enclosures. When looking to implement soilless growing techniques, particularly as tools for development, it is often necessary to think outside the normal ratios, flow-charts, and equipment lists that we assume when designing U.S.- or EU-style facilities for commercial production.
