Fishing For The Future:
Aquaculture and Aquaponics

Champlain Sturgeon

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Population growth is having a huge and compounding effect on the world fisheries. From the year 1960 to 2012, the world’s population more than doubled from 3 billion people to over 7 billion people (US Census Bureau, 2011). Over that same time period, the combination of increased population and increased affluence has driven a 5 fold increase in worldwide fish consumption from about 25 million tons in 1960 to over 130 million tons today (UN FAO, 2011). The effect on the world’s open water fisheries has been dramatic and often devastating. Increased fishing fleets and more aggressive fishing techniques have brought many of the world’s most productive fisheries to the brink of collapse. Despite increased fishing, the open water fish harvest has been flat since 1985 (UN FAO, 2011). If we continue to overfish the seas, we may lose key species of fish forever.

So how do we feed a growing world that increasingly wants to improve their diet and eat fish? The same way that we feed the world plant foods, through controlled and sustainable farming. Aquaculture and its next-generation evolution, aquaponics, are the answer to reducing the pressure on our open water fisheries, and feeding the world.

The Ever Increasing Demand For Seafood

The population of the world continues to grow dramatically. Figure 1 shows that over just the last 50 years, the world’s population has soared from 3 billion in 1960 to 7 billion today (US Census Bureau, 2011). At the same time, the globalization of industry is increasing the household income of much of the world’s population. An example is China. From 1992 to 2008, the disposable income of an urban dweller in China surged by 800% (BBC News, 2011).

Not surprisingly, as people have more income, they tend to want to eat more meat and fish. Figure 2 shows that as the per person income of a country increases, there can be as much as a 700% increase in that person's consumption of meat and fish.

Figure 1: World Population Growth (US Census Bureau, 2011) Figure 2: Protein Consumption vs Income (USDA, 2004)

The combination of increased population, increased wealth and shifting diets have led to a huge increase in demand for fish. Figure 3 shows that from 1960 to today, there has been a 500% increase in the demand for fish worldwide. Demand increases like this have had huge consequences for the fish population of the world's oceans, lakes and rivers.

Figure 3: World Fish Consumption (UN FAO, 2011)

Open Water Fishing

Overview of Open-Water Fishing

The open-water fishing industry provides employment and economic benefits to a large number of people. The industry uses a wide variety of methods of catching that can range from hand picking to highly sophisticated fish harvesting systems. Half of the world's seafood is caught or collected by small-scale fishermen operating millions of fishing crafts using traps and pots, hook and line, and a wide variety of nets (Indian Council of Agricultural Research, 2006). Through the years, traditional fishing gears have been modified and newer more efficient fishing systems have been introduced. Some of the more significant systems, as shown in Figure 4, are fish harvesting systems like trawls, seines, lines, gill nets and entangling nets and traps (Montgomerie, 2005).

Figure 4: Basic Commercial Fishing Methods (Montgomerie, 2005)

Benefits and Challenges of Open Water Fishing

The benefit of modern commercial open-water fishing techniques is that they are a well-tested, proven and relatively low cost method for collecting large amounts of fish. They have provided food and jobs in many communities. For many people fishing is not just a job but an identity and sometimes the identity of an entire coastal town. During the nineteenth and twentieth centuries, innovations in fishing and improvements in transportation helped fishers boost their catches and consequently their sales of seafood. Large-scale or "industrial" fishing can be traced back to the 1870s and 1880s. During that time, fishers started trawling with steam-powered vessels in British and European waters, such as the North Sea. At about the same time, railroads connected fishing ports to interior towns, increasing markets for fish. As near-shore fishing grounds became depleted, steam trawlers fished far from their home ports by the 1920s and 1930s. Steam-powered trawlers came to dominate Canadian and American cod fisheries, and the introduction of fast-freezing techniques, enhanced operations. Expansion and significant increases in global fishing occurred in the decades following the Second World War. New, long-distance fishing and processing vessels were able to stay at sea for months at a time. People believed that the oceans would provide an endless source of protein at reasonable costs. In the 1950s and 1960s, some scientists estimated that the oceans and seas could sustain an annual seafood catch of 200-350 million metric tons (or tonnes) per year, more than twice as much as was ever actually achieved. A metric ton (or tonne) is 1,000 kilograms or 2,204 pounds (Blackford, 2008).

Figure 5 shows the power of modern open water fishing techniques. From 1950 to 1990, the open water fish catch has more than quadrupled. As human population has increased, better fishing technology has been applied and allowed many millions of people to have good nutrition through the harvest from the sea.

Figure 5: Worldwide Fish Harvest From Open-water Fishing (UN FAO, 2012)

Figure 5 also shows, however, that the benefits of modern open water fishing has its limits. As the catch has continued to increase over the years, the fish population in many areas has started to become stressed, or even begun to collapse. The stress in these fish communities has meant that since about 1990, despite huge efforts at trying to increase the fish catch, the overall world capture of wild-caught fish has been stagnant at about 90 metric tonnes per year.

There are two parts to understanding the overfishing problem. The first is that the newer, more aggressive industrial fishing techniques, while efficient from an economic standpoint, are inefficient from an environmental impact standpoint. Figure 6 shows the various ways in which commercial fishing boats with large cast nets captures much more than just the targeted fish species and cause unintended mortality to different marine species.

Figure 6: The Inefficiencies of Industrial Fishing ( University of Waikato, 2012)

The second part of the problem is the overfishing itself. As the population grows and increased affluence drives an increased demand for seafood, commercial fisherman are simply capturing too many fish and driving down populations to the point of collapse. Collapse is defined as the point at which a fish population is so low that it cannot regenerate its numbers fast enough to sustain further commercial fishing. The problem is illustrated below. Figure 7 shows that between 1950 and 2003, about 30% of the world's seafood species have collapsed. If we do not make significant changes to our overfishing, the UN projects that by 2050 the world could face the collapse of almost 100% of commercially important open-water fish populations. The Northwest Atlantic Cod provides a good example of what could happen. Figure 8 shows that the catch of this popular fish crashed from 1.8 million tonnes in the 1960's to essentially zero today.

Figure 7: Collapse of Seafood Species 1950 to 2003
(UN FAO, 2011a)
Figure 8: Collapse of Northwest Atlantic Cod
(UN FAO, 2012)

Government Policies and Regulation

In 1945, President Truman extended United States control to all natural resources of its continental shelf. Many nations were quick to follow Truman’s lead and gain control over the use of their continental shelves. In an effort to ensure that ocean resources would be protected and kept available for use by their own citizens the United Nations held conferences on the Law of Sea Conventions in the 1950’s and 60’s. However, little progress was made until 1970, when many nations declared 200-mile Exclusive Economic Zones (EEZs) out from their shorelines. The EEZs helped to bring one-third of the ocean waters under national controls by the year 2000. This meant that 75 to 90 percent of the globe’s commercial fish were also under national control and many nations were interested in placing limits on fish catches to make the EEZs more sustainable (Blackford, 2008).

The United States claimed its Exclusive Economic Zones (EEZs) in 1976 with some additional changes in 1996. The law was referred to as the Federal Fishery Conservation and Management Act (FCMA) and it extended national control over oil, minerals, and fish 200 miles out from shore. This essentially eliminated foreign fishers from American waters and opened up the waters for more American fishers. In American waters, fishing trends initially rose for wild species, peaking around 1987 at 5.6 million tons, but flattening out around 2004 at 5 million tons (Blackford, 2008).

In an effort to help manage the EEZs the US set up eight regional management councils to determine Total Allowable Catches (TACs) for different types of fish. While the established TACs strived to prevent overfishing and abuse, it was really the fishers’ choice to adhere to them. In 1996, the FCMA required that the nation's eight fishery management councils devise ten-year plans to rebuild depleted fisheries. In 1998, the U.S. Marine Fisheries Service performed a survey of 300 major fish species that showed that 90 were over-fished, 10 were approaching that condition, and 200 were healthy. In 2006, the news was worse. A new survey revealed that 82 percent of the major fished stocks in American waters suffered from over-fishing (Blackford, 2008).

The effectiveness of the US regulations has varied. For instance, regulations supporting sustainable harvests for bottom fish like the Atlantic cod in the Northwest Atlantic have largely failed. However, regulations on fishing for salmon, crab, pollock, halibut, Pacific cod, and sablefish in the Northeast Pacific has been more successful (Blackford, 2008). Unfortunately, even when U.S. governmental regulations are successful in certain fisheries, those fisheries are still not able to supply the ever growing demand for seafood.

Sustainable Alternative #1: Aquaculture

Overview of Aquaculture

According to the Food and Agriculture Organization of the United Nations (FAO), aquaculture is the farming of aquatic organisms such as fish, mollusks, and crustaceans (freshwater and saltwater populations) under controlled conditions (Barton 2007). Farming is growing a species, for the purpose of production, in an enclosed environment. Farming of fish in an enclosed protected environment has several benefits such as the ability to stock the farm with young fish, feeding and protection from predators. Particular kinds of aquaculture include fish farming, shrimp farming, oyster farming, alga-culture (such as seaweed farming), and the cultivation of ornamental fish (Barton 2007). As shown in Figures 9, 10, 11, and 12, there are four major types of aquaculture: ocean-based open-water farming, river-based open-water farming, pond-based farming and tank-based farming. Open water aquaculture is one of the most common form of aquaculture. In both ocean-based and river-based aquaculture, the seafood being grown is confined to a certain area by nets or cages.

Figure 9: Ocean-based Aquaculture
(Environmental Watch, 2013)
Figure 10: River-based Aquaculture
(Qingdao Qihang, 2014)
Figure 11: Pond-based Aquaculture
(Smith Pond Nursery, 2006)
Figure 12: Tank-based Aquaculture
(Local Ocean Fish Farm, 2010)

Benefits and Challenges of Aquaculture

The key benefit of aquaculture is high volume production of seafood. FAO aquaculture production statistics show that 541 different species were produced via aquaculture. These include: 327 finfishes, 102 mollusks, 62 crustaceans, 6 amphibians and reptiles, 9 aquatic invertebrates and 35 algae (UN FAO, 2012).

Figure 13 shows just how great an impact aquaculture is already having, growing from almost no production in 1950, to a just few million tonnes in 1970, then rapidly expanding to an impressive 60 million tonnes in 2010.

Figure 13: Worldwide Fish Harvest: Open-water and Aquaculture (UN FAO, 2012)

In 2010, the composition of world aquaculture production was: freshwater fishes (56%, 34 million tonnes), mollusks (24%, 14 million tonnes), crustaceans (10%, 6 million tonnes), diadromous fishes (6%, 3.6 million tonnes), marine fishes (3%, 1.8 million tonnes) and other aquatic animals (1.4%, 0.8 million tonnes). Interestingly, aquaculture production already exceeds capture production for many of the staple species for aquaculture. For example, the wild catch accounts for less than 1 percent of Atlantic salmon production, and farmed marine shrimps contribute 55 percent to the total global production (UN FAO, 2012). Figures 14, 15 and 16 summarize the production volumes of the major categories of aquaculture produced seafood.

Figure 14: 2010 Aquaculture Production of Freshwater Species
(UN FAO, 2012)
Figure 15: 2010 Aquaculture Production of Diadromous Species
(UN FAO, 2012))
Figure 16: 2010 Aquaculture Production of Marine Species
(UN FAO, 2012)

Although the benefits of aquaculture in feeding the world's population are clear, there are some serious issues associated with Aquaculture. The largest problem is the concentration of the waste from very large numbers of fish in a small area. In open-water farming, these wastes can cause severe environmental problems. In pond and tank aquaculture, these wastes require expensive water purification systems.

One unique solution to some of the pollution issues with aquaculture is Integrated Multi-Trophic Aquaculture (IMTA) (CAIA, 2012). IMTA is the farming of different aquaculture species together in a way that allows one species’ wastes to be recycled as feed for another. An IMTA systems combines an aquaculture species that requires external feeding such as salmon, with species capable of getting nutrients from the wastes of the ‘fed’ species. By recycling nutrients that would otherwise be wasted, IMTA systems provides farmers the potential of increased economic gains. IMTA systems can also be beneficial to the environment by reducing waste products in the marine environment as well as a decreased risk of algal blooms and cloudy water (CAIA, 2012).

The challenge with this type of system is maintaining the balance between the two species being raised. There are, however, excellent examples of the IMTA technique working well. The Pacific SEA-lab in British Columbia is one example. Pacific SEA-lab has developed a small, commercial scale IMTA facility that is currently investigating the potential of combining sablefish, scallops, oysters, cockles, sea cucumbers, and kelps in an intensive IMTA system design. This pilot IMTA initiative, also referred to as a Sustainable Ecological Aquaculture (SEA-System), is supported through an industry-academia partnership that is exploring the environmental and socio-economic benefits associated with this form of integrated aquaculture (CAIA, 2012).

Sustainable Alternative #2: Aquaponics

Overview of Aquaponics

Aquaponics is defined as a food production system that combines conventional aquaculture, (raising aquatic animals such as snails, fish, crayfish or prawns in tanks), with hydroponics (cultivating plants in water) in a symbiotic environment (Bernstein 2011). Aquaponics systems have the ability to produce a variety of vegetable and animal products that can be sold at market. As shown in Figure 17, the aquaponics system uses the fish and plants to recycle nutrients and waste in a sustainable, recirculating and ever-connected system. Its internal recycling system between animals and plants attempts to mimic the nutrient recycling system that is found in nature. One of the most important nutrients in this recycling system is nitrogen. Fish release two types of waste that contain nitrogen: dissolved nitrogen waste and solid waste. Bacteria in the water eventually convert the dissolved nitrogen waste into another type of waste called nitrate. Nitrate is toxic to fish. This is why all fish tanks (even a home fish tank) requires a water filtration device. In aquaculture systems that only raise fish, farmers have to manually filter out the nitrate and throw it away as waste. Aquaponics systems, on the other hand, grow plant crops that absorb nitrate through their roots. This nitrate absorption helps plant growth in addition to protecting the fish from poisonous dissolved waste (Bernstein 2011).

In nature, solid fish waste is not broken down by bacteria. Other organisms such as earthworms do this job. Some aquaponic systems try to replicate this natural cycle and include earthworms as one of their components. In such systems, the solid waste from the fish tank is put it into a compost system where the earthworms break down the solids into vermicompost, a nutrient-rich food source for plants. One of the few outside inputs that aquaponics may need is fish feed. This problem can be fixed because fish feed can come from the aquaponics system itself if growers grow duckweed, a water plant that many fish species eat. Though many different species of fish can thrive in an aquaponics system, tilapia is one of the best suited for aquaponics. Tilapia eat duckweed and adapt to a wide variety of water conditions. On the plant side, leafy vegetables like lettuce and herbs such as basil grow best in aquaponics systems (Bernstein 2011).

Figure 17: Basic Operation of an Aquaponics System (Aquaponics Illustration, 2013)

Aquaponics systems can have a wide variety of appearances. Some, like those shown in Figures 18 and 19, feature pre-fabricated industrial-size tanks outfitted with complicated filtration technology while others are simpler, homemade setups of plastic barrels and piping.

The five main inputs to the system are water, oxygen, light, feed given to the aquatic animals, and electricity to pump, filter, and oxygenate the water. Minnows are often added to replace grown fish that are taken out from the system to retain a stable system. In terms of outputs, an aquaponics system may continually yield plants such as vegetables grown in hydroponics, and edible aquatic species raised in an aquaculture. Typical build ratios are 0.5 to 1 square foot of grow space for every 1 US gal of aquaculture water in the system. 1 US gal of water can support between 0.5 lb and 1 lb of fish stock depending on aeration and filtration (Bernstein 2011).

Figure 18: Aquaponics System For Commercial Operations
(Epcot Aquaponics 2012)
Figure 19: Aquaponics System For Personal Use
(Food Probe, 2014)

Benefits and Challenges of Aquaponics

Aquaponic systems do not typically discharge or exchange water under normal operation, but instead recirculate and reuse water very effectively. From an environmental pollution standpoint, this is a huge advantage. The system relies on the relationship between the animals and the plants to maintain a stable aquatic environment that has a minimum amount of fluctuation in nutrient and oxygen levels. Water is added only to replace water loss from absorption and transpiration by plants, evaporation into the air from surface water, overflow from the system from rainfall, and removal of biomass such as settled solid wastes from the system. As a result, aquaponics only uses about 2% of the water that a conventionally irrigated farm requires for the same vegetable production. This allows for aquaponic production of both crops and fish in areas where water or fertile land is scarce (Bernstein 2011).

As in many aquaculture based systems, feed for the fish in aquaponics usually consists of fish meal that is derived from lower-valued fish species. As discussed above, the wild fish stocks in the world are being depleted. This makes the current practice of using open-water wild caught fish as aquaponics feed unsustainable. Organic fish feeds may prove to be a viable alternative that relieves this concern. Other alternative feeds that can be used include: duckweed grown in the aquaponics system itself, worms grown from vermiculture composting of the fish solid waste and black soldier fly larvae grown in compost (Bernstein 2011).

But all is not easy with an aquaponics system. The downside to aquaponics is that, in order to keep both fish and plants thriving, one must maintain a very careful balancing act. The tank water pH must be kept at an acceptable level for both the fish and the plants. Dead fish must be taken out of the aquarium as soon as possible, due to the high amounts of ammonia they release. Although ammonia from fish waste is converted into nitrate for plant growth by bacteria, the ammonia from dead fish is excessive. The farmer must also choose his fish carefully, ensuring that they can coexist with one another and within the conditions provided in the aquaponics tank. While careful design can minimize the risk, aquaponics systems can have multiple 'single points of failure' where problems such as an electrical failure or a pipe blockage can lead to a complete loss of fish stock (Bernstein 2011).


It is clear that population growth is having a huge and compounding effect on the world fisheries. With the world’s population now at 7 billion and rising to a possible 9 to 11 billion, traditional open-water fishing techniques simply cannot meet the demand for over 130 tonnes of seafood per year. Overfishing has already caused the collapse of the population of about 30% of the world's most important fish species. The Northwest Atlantic Cod, once a prized catch producing 1.8 million tonnes per year, is now all but fished out. If we do not make a dramatic change, we may face the collapse of 100% of the most important open-water fish species by 2050. To feed a growing world that increasingly wants to improve their diet and eat fish, we need to use the same techniques that we use to feed the world plant food: controlled and sustainable farming.

Aquaculture and its next-generation evolution, aquaponics, are the answer. With aquaculture, we can move production of seafood from the open oceans and rivers to controlled farms. From providing just a small amount of seafood in 1970, aquaculture has expanded dramatically to produce 60 million tonnes of seafood per year, about 46% of the world's seafood demand. But because of the concentration of so many animals in a relatively small space, aquaculture can put its own stresses on the environment, particularly in the form of pollution from fish waste.

Ultimately, the most environmentally friendly and sustainable way to produce seafood is combining aquaculture with agriculture. Aquaponics is a unique system that uses the waste products from fish production to supply nutrients to growing plants. The water, which has been cleansed by the growing plants, is then recirculated back to the fish. In some cases, the aquaponics system can be used to grow both, fish and the plants that feed the fish. By using aquaponic systems, we get the benefit of both high production rates of fish and environmental sustainability.

For producing seafood to feed a growing world, the future is aquaculture and aquaponics.

Take Action

Promotion of aquaculture and its next-generation evolution, aquaponics is something each person can be part of. One important action is writing to lawmakers to ask for support of new legislation, particularly tax credits for aquaculture and aquaponic farmers. Another is writing to industry associations and individual businesses asking them to support aquaculture and aquaponics through their purchases.

Please click on the links below to see example letters that you can use to help promote change.
Advocacy Letter to Lawmaker
Advocacy Letter to Industry Association


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