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AQUACULTURE PART 2

In our latest post we covered some basics on aquaculture. So far we know since when has aquaculture been around and that it is the fastest growing sector in the food industry. We learned that aquaculture is a great way to solve the growing demand. Depending on the growth method and means used, e.g. antibiotics, aquaculture can be more or less sustainable.


Today, let’s cover the sustainable aspects of aquaculture and their impact.


POND MANAGEMENT SYSTEMS


One of the most advanced sustainability options in aquaculture are ponds. They provide many resources needed to grow aquatic animals and plants in one self-contained unit. So, how do ponds actually work?


1) Phytoplankton use solar energy to drive photosynthesis and then generate oxygen as a byproduct of photosynthesis


2) Phytoplankton generate organic matter and assimilate carbon dioxide, ammonia and mineral nutrients from the water


3) The algal photosynthesis treats the generated waste, so that they do not accumulate to toxic levels.


PARTITIONED AQUACULTURE PONDS


Partitioned aquaculture ponds combine high-density raceway culture of fish with high-rate algal growth oxidation channels (Turker et al., 2002). On the image below you can spot specific containters where fish are kept.

Retrieved from Turker and colleagues (2002)


From an economic perspective, there is a benefit of growing two types of fish within the same container (Tucker et al., 2014). Boyd and colleagues (2020) point out how in theory, if the rate of the algal photosynthesis is doubled, the rate of ammonia removal and fish production may be doubled.


BIOFLOC TECHNOLOGY


The previously mentioned partitioned aquaculture system is mainly driven by algal metabolism. One drawback is that algal metabolism is dependent on weather conditions and thus partially out of the scope of control.


Biofloc ponds remove waste by complex communities of autotrophic and heterotrophic microorganisms. But, what are bioflocs?


Biofloc technology (BT) is defined as: “the use of aggregates of bacteria, algae, or protozoa, held together in a matrix along with particulate organic matter for the purpose of improving water quality, waste treatment and disease prevention in intensive aquaculture systems (El-Sayed, 2020)”.


Biofloc systems improve a variety of things, such as biosecurity, feed conversion, water quality, water use efficiency. Moreover, they increase land use efficiency and reduce sensitivity to light fluctuations (Stasinopoulos et al., 2009).


According to Crab and colleagues (2012), there are two ways of implementing biofloc systems, shown on the image below.



Retrieved from Crab and colleagues (2012)

FISH FEED


When it comes to fish feed, its quality and sustainability is mostly shown within its content and presence of prebiotics, probiotics and various enzymes. However, one initative seen by aquaculture companies is their own R&D on fish feed. One example is the Croatian company Cromaris, they commit to their high quality and standardized production of fish.


CONCLUSION


How can aquaculture be sustainable? By using different organic systems who reinforce each other.

How can you contribute? Find a local aquaculture player with extensive R&D and check for open vacancies. That way you can contribute to sea conservation and sustainability, on a local level.


Reference


Turker, H., Eversole, A., & Brune, D. (2002, February 1). Partitioned aquaculture systems [Review of Partitioned aquaculture systems]. Global Seafood. www.globalseafood.org

Tucker, C., Brune, D., & Torrans, E. (2014, June 1). Partitioned Pond Aquaculture Systems. World Aquaculture Society | Partitioned Pond Aquaculture Systems - World Aquaculture Society. Retrieved February 2, 2022, from https://www.was.org/articles/partitioned-pond-aquaculture-systems.aspx#.YfpoL-rMK5d

Boyd, C. E., D'Abramo, L. R., Glencross, B. D., Huyben, D. C., Juarez, L. M., Lockwood, G. S., McNevin, A. A., Tacon, A. G., Teletchea, F., Tomasso, J. R., Tucker, C. S., & Valenti, W. C. (2020). Achieving sustainable aquaculture: Historical and current perspectives and future needs and challenges. Journal of the World Aquaculture Society, 51(3), 578–633. https://doi.org/10.1111/jwas.12714

El-Sayed, A.-F. M. (2020). Chapter 13 - Technological innovations. In Tilapia culture: Second edition (2nd ed., pp. 297–328). essay, Academic Press.

Stasinopoulos, P., Smith, M., Hargroves, K., & Desha, C. (2009). Whole system design an integrated approach to sustainable engineering (1st ed.). Earthscan.

Crab, R., Defoirdt, T., Bossier, P., & Verstraete, W. (2012). Biofloc technology in aquaculture: Beneficial effects and future challenges. Aquaculture, 356-357, 351–356. https://doi.org/10.1016/j.aquaculture.2012.04.046

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