Many of us love a good fish supper, and eating fish is something we can all too easily take for granted. According to the WWF, the average person eats twice as much fish as we did 50 years ago, around 19k. a year. Typically, we rarely spare a thought for where our fish comes from, yet, our seas are overfished1. As a result, in order to meet demand, fish farming is becoming more prevalent. In this article we explore the growth and types of fish farming out there, asking is fish farming sustainable?
Throughout past years, our fish has been caught in the wild by trawlers. They would essentially collect tons of fish using vast nets. To meet increasing demand large scale commercial fishing has essentially overfished certain species. So much so that FOA research shows that 90% of the world fish stocks are fully fished. Which, in turn, has resulted in declining fish stocks at sea for many species we enjoy eating.
The mass industrial scale of fishing in this way has caused us a number of other problems. It results in the needless death of smaller fish. What’s more, other, unwanted species get caught and killed unscrupulously amongst the catches4.
Many countries have placed bans on fishing for certain species and there are stringent quotas to endeavour to protect fish stocks. However, many stocks have been dwindling, particularly with species such as cod7 whereby stocks have dropped by 31% since 2015.
So, in response to this situation, sustainable fish farming is helping to deal with the range of problems that have come with open water, traditional commercial fishing.
Today, fish farming has become a fast-growth industry as wild fish stocks have become depleted. Needless to say, the demand for fish remains high, and fish farming helps to fill the gaps that have resulted. Essentially, keeping up with demand and potentially taking over from mass industrialised wild fishing.
On the surface, sustainable fish farming is the farming of fish in an eco-friendly friendly way that can sustain itself, allowing fish stocks to replenish without causing detrimental environmental harm.
Whereas definitions can vary, for a fish farm to be sustainable fish are grown in a healthy environment, avoiding the use of chemicals and the overuse of antibiotics5.
As such, they farm fish more naturally without the use of unsustainable practices to mass-produce fish quickly including artificial means to expedite their growth.
Also known as aquaculture, there is a very fine line between sustainable farming and practices that are not so sustainable3.
Sustainable fish farms cultivate fish in a way that minimises the impact on the environment from more intensive agricultural processes. For example, the less sustainable fish farms, and many exist, might remove large quantities of water from natural reservoirs or lakes. Further, they can then exit used water that contains chemicals back into the environment. Or those at sea may introduce chemicals into the water that have a detrimental effect on nearby ecosystems.
Unlike fish farms that use unsustainable practices, the aquaculture practices of sustainable fish farms ensure that the fish remain healthy. To do so, they work hard to prevent damage to nature's ecosystems. They avoid using chemicals, additives, hormones or antibiotics, all of which can cause further problems down the food chain.
Sustainable fish farms also take great care in what they feed their fish. They don’t use animal protein as food and they do not use fish pellets that consist of animal waste byproducts. Using natural food stocks that have the right balance of nutrients ensure fish grow naturally.
Most of us won’t think twice about the water that fish are grown in. However, this is a very important aspect as sustainable fish farms use water in a responsible way. They ensure they actively monitor water quality and they use a small surface area too. This ensures that fish in the area and are native are not forced out of the area by farmed fish.
It is not just about growing the fish. Fish farms can produce a lot of waste and sustainable fish farms treat waste responsibly. They use as much of the fish as possible, preventing parts that would otherwise go to waste needing to be disposed of.
This will include the likes of fish oils or fish solids that we can use as animal feed or even use as biodiesel. The pharmaceutical industry uses gelatin, in which fish skin plays a role. What’s more, it can also be used as an alternative for leather. Along with this, collagen from the skin can be used by cosmetic manufacturers too.
While many of us might think of fish farms as being located in open lakes or the ocean that is not always the case. Many farms are now moving inland and are using land-based aquaculture productions systems6. This is a particularly useful way of managing demand in urban areas.
Along with this, some fish farms are actually heading out to the open ocean. Here they are able to achieve an increase in sustainability as a result of cleaner water and predictable water flows that help to reduce pests and waste8.
Sustainable fish farming can take many forms. However, the aim of it is to limit environmental impacts. What’s more, it helps to support world resources. So whether it is farmed shrimp or farmed salmon, there are different forms of fish farms in use.
As far as sustainability goes, land-based farms could be better for the environment. Farming fish on land helps make it possible to contain chemicals and waste.
Whereas the downside is that land-based farms need to recreate a healthy natural habitat through tanks and filtration. There is an environmental overhead to running all the machines, with the more sustainable fish farms powering their endeavours using renewable energy such as solar or wind.
Bottom or off-bottom culture fish farms make use of the natural habitat2. This is perfect for growing shellfish such as oysters or mussels. They use large trays to grow them on the seabed or they can be grown using floating mesh nets.
These farms are now becoming more apparent in the open ocean. Perfect for farming large amounts of fish, there is an abundance of space too. They also provide a specific level of sustainability too. The water is clean which is healthier for the fish while the currents provide a natural habitat while washing away pests and waste.
Growing Cobia, this is the biggest open-ocean farm in the world. The farm hatches fish eggs in a hatchery and then moves them into vast pens that they position deep beneath the surface for 14 months. The waters are clean and the fish thrive in this farm off the coast of Panama.
This project considers the ability to farm fish by using an Aquapod that they attach to a boat that drifts in deep water. They’ve also experimented with barges in the ocean to which an Aquapod is attached. The aim is to potentially add propellers as well as a GPS system. By being able to be self-propelled the barge can then transport farmed fish to the next phase of the process.
One of the crucial aspects of any fish farm is the food that they are fed. In the past, unsustainable methods were problematic for the environment. Despite this, Kampachi Farm has been experimenting with fish diets. They have fed their fish using soybeans and plants and have always fed their fish a diet with no fishmeal. All of these experimental diets were similar to that of a normal diet.
Along with this, fish food made from corn, wheat and soy has also been developed. Using fatty acids from algae as well as amino acids and soybean or canola oil, they were able to replace the fish oil. As a result, they found that the levels of PCB and mercury were lower than in those fish that were given a fishmeal diet.
Our need for fresh fish is still on the rise. However, the supply cannot keep up with demand, unless we want to deplete stock levels and harm the environment. Therefore, sustainable fish farms could be the way to go.
While improvements have been made, there is still a long way to go. This is particularly true in ensuring that we can scale it up to meet demand. However, sustainable fish farming can only be successful if consumers know how to eat sustainable fish.
As methods and practices are improving greatly, consumers also have to play a role.
They can find out where and how the fish was caught. It's possible to identify this on labels or by asking the fishmonger when purchasing from a fish market.
We can also look out for sustainable fish choices, such as haddock instead of cod. From sustainable fish farming to making better choices, there is a lot that can be done to ensure we take care of our ocean, our fish and continue to enjoy fresh fish as consumers.
|Stergiou, Konstantinos. (2002). Overfishing, Tropicalization of Fish Stocks, Uncertainty and Ecosystem Management: Resharpening Ockham's Razor. Fish. Res.. 55. 10.1016/S0165-7836(01)00279-X.|
|Influence of suspended and off-bottom mussel culture on the sea bottom and benthic habitats: a review. Christopher W. McKindsey, Philippe Archambault, Myriam D. Callier, Frédéric Olivierd. Ocean and Environmental Sciences Division, Maurice-Lamontagne Institute, Fisheries and Oceans Canada|
|Lazard, J., Baruthio, A., Mathé, S., Rey-Valette, H., Chia, E., Clément, O., . . . René, F. (2010). Aquaculture system diversity and sustainable development: Fish farms and their representation. Aquatic Living Resources, 23(2), 187-198. doi:10.1051/alr/2010018|
|Iñarra B. et al. (2019) What to Do with Unwanted Catches: Valorisation Options and Selection Strategies. In: Uhlmann S., Ulrich C., Kennelly S. (eds) The European Landing Obligation. Springer, Cham|
|Romero, Jaime & Feijoo, Carmen & Navarrete, Paola. (2012). Antibiotics in Aquaculture – Use, Abuse and Alternatives. 10.5772/28157.|
|Yossi Tal, Harold J. Schreier, Kevin R. Sowers, John D. Stubblefield, Allen R. Place, Yonathan Zohar, Environmentally sustainable land-based marine aquaculture, Aquaculture, Volume 286, Issues 1–2, 2009, Pages 28-35, ISSN 0044-8486, https://doi.org/10.1016/j.aquaculture.2008.08.043|
|Lindegren M, Diekmann R, Möllmann C (2010) Regime shifts, resilience and recovery of a cod stock. Mar Ecol Prog Ser 402:239-253. https://doi.org/10.3354/meps08454|
|Benetti, D.D., Benetti, G.I., Rivera, J., Sardenberg, B., & O'Hanlon, B. (2010). Site Selection Criteria for Open Ocean Aquaculture.|