New Guide identifies strategies to improve the life of aquaculture fish

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By Milthon Lujan

Portugal – Recent studies show that fish are sensitive and sentient animals, i. e. they can sense emotions as a response to their environment. However, these characteristics of fish have not yet been reflected in the aquaculture industry, which is now beginning to take the first steps to ensure the welfare of farmed fish.


Aquaculture, whether freshwater or saltwater, is one of the fastest-growing food-producing sectors in the world. In this industry, more than 100 billion fish are cultivated, transported and slaughtered each year. However, the tanks and cages used to cultivate fish are not designed to meet their basic welfare needs and are often completely devoid of elements found in their natural habitats.

This “environmental poverty” found in aquaculture not only decreases animal welfare but can also be responsible for considerable production losses in an industry that has been growing globally in recent years. In a new study published in the journal Reviews in Aquaculture, our researchers Pablo Arechavala, Maria Cabrera, Caroline Maia and João Saraiva identify strategies to avoid these situations and improve the animal welfare of aquaculture fish.

Study explores in detail the potential of environmental enrichment in aquaculture 

‘Environmental enrichment’ consists in intentionally increasing the complexity of the farming environment to improve the welfare of captive animals. In aquaculture, there are several methods of achieving this: introducing objects or structures into the tanks, using lighting, shadows, colours and sounds that provide sensory stimuli, providing social interaction with other individuals or even other species, simulating typical activities of certain species (e.g., introducing currents that stimulate swimming) or even introducing feeds that stimulate feeding behaviour. With these strategies, tanks and cages can mimic the environment that fish find in their natural habitat – and the gains in production can be surprising.

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Environmental enrichment is a common practice in land-farm animals, especially in premium products, yet in the aquaculture sector, it is still residual. Why do we find this discrepancy? Firstly, because the sentient capabilities of fish have only recently been discovered. And secondly, the aquaculture industry focuses primarily on production parameters, leaving little space for changes in working protocols. 


The study now published highlights the benefits that these strategies can bring when properly applied. “Environmental enrichment stimulates fish biology, promoting, for example, disease resistance and recovery in a natural way. We are essentially bringing nature to meet the animals in their farmed environment, and the fish appreciate it,” says João Saraiva, leader of the research team. “In addition, environmental enrichment can also allow a better growth of the animals, better resistance to diseases and better meat quality, all this avoiding the use of medicines or chemical products.”

Solutions adapted to individual species

The implementation of environmental enrichment measures must take into consideration the biology and natural behaviour of each species, and must also be tested for each company, accounting for specific protocols in each production step, including the quality and hygiene of the production environment. An example of this type of considerations is the study led by the CCMAR team on environmental enrichment in seabream farming. This study has shown that for this species, hanging simple sisal ropes in the centre of the cages, from the surface almost to the bottom, reproduces some of the complexity of their natural environment and increases their welfare.

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A step-by-step guide to implements fish welfare measures

One of the highlights of this recent study is the proposal of a step-by-step guide for making decisions about what kind of environmental enrichment to implement, how to evaluate the results, and how to move forward in the process. “It is important to get the message across that there is no magic enrichment formula that works for all systems. Each species, stage of development, production system, working protocols, and even type of business generates a unique case that may have a different solution. It is to help discover that unique solution, and how to implement it, that this work can be very useful” says João Saraiva. “In any case, it is also part of our work to collaborate with the industry to develop new enrichment measures and new indicators to better assess performance and welfare gains.”

Welfare: the next big challenge for aquaculture

Following the footsteps of the remaining animal production industry and with the recognition of the mental capabilities and sentience of fish (with the consequent ethical repercussions), the next big challenge for the aquaculture sector will be welfare. “Many certification labels already have reference to animal welfare measures, responding to both consumer pressure and scientific findings. Some certifications even require environmental enrichment measures, as is the case with the Friend Of The Sea label, for example” says João Saraiva. “The future will always be driven by quality, and welfare is a way to improve the quality of aquaculture products. Environmental enrichment is one of the most direct ways to improve the welfare of farmed fish.”


Pablo Arechavala-Lopez, 
Fish Ethology and Welfare Group, 
Centro de Ciências do Mar (CCMAR), 
Universidade do Algarve
Email: pablo@fishethogroup.net

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Reference (open access):
Pablo Arechavala-Lopez, Maria J. Cabrera-Álvarez, Caroline M. Maia, Joao L. Saraiva. 2021. Environmental enrichment in fish aquaculture: A review of fundamental and practical aspects. Rev Aquac. 2021;00:1–25. 

Source: Centro de Ciências do Mar (CCMAR)

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