Researchers discover that innovations in seabream cultivation tanks improve production and well-being

The study showed “a change in behavior and a decrease in stress indicators”

A study, coordinated by researchers from the Algarve Marine Science Center (CCMAR) at the University of Algarve (UAlg), revealed that the use of suspended ropes in seabream breeding tanks reduced the fish's stress levels and improved their health. , starting to adopt behaviors similar to those in the natural environment.

The study showed «the change in behavior and reduction in stress indicators (plasma cortisol and glucose levels), after the placement of simple structures in the tanks that are easy to apply by the industry and which can have a positive impact on the entire production», says the group of researchers.

These results are especially relevant because they involve breeders, animals that produce thousands of eggs and larvae that will later be cultivated and where “no one wants to touch”, which, for the study coordinator, could be “harmful”.

«A breeder spends several years in relatively small tanks and in an extremely poor environment to produce thousands of fry, and this quantity has to be right and of good quality. The environmental enrichment we used in this study proved to be positive for the behavior of the breeders, their stress levels and their health. Spending years in an almost sterile environment is not natural for them and can weaken them and the results show that we can prevent this from happening with extremely simple measures», says João Saraiva.

The biologist, responsible for the Fish Ethology and Welfare group at CCMAR and president of the Fish Etho Group, adds that these structures are "especially important" in the cultivation of seabream, as this is an animal that, in its habitat, "uses and interacts” with elements on the seabed, and it is therefore important to provide them with “something similar to what they have in the natural environment”.

Unlike other species used for human consumption, farmed fish are “not domesticated”.

If livestock animals (cows, goats, pigs...) have already undergone thousands of years of selection and domestication, adapted to an environment far from nature, a fish cultivated today continues to be very similar to the one that lives in the sea. It is therefore essential to create a more naturalized environment for fish, in order to improve their well-being and, consequently, their health.

The ease of placing and removing these structures, without disturbing cleaning and production routines, was one of the researchers' concerns, as the intention is that they will be used permanently by producers. They looked for a solution that combined the needs of the animals, the particularities of the production itself and ease of handling without harming the quality of the water.

«The structures are easy to remove, easy to clean and, as we have seen, they do not have any problems in terms of disease, they do not increase the load of bacteria or other organisms that could affect the fish», he highlights.

Each element consisted of nine sisal ropes attached to a four-meter square float, hanging in the water column “almost to the bottom”, creating an environment where the animals have to navigate a more complex environment.

Some fish started to adopt behaviors that had not previously been observed, such as the establishment of social hierarchies and territorial behaviors, more typical of the species, but without showing excessive aggression.

The next step is the creation of a product with the Portuguese company Ergomarine – producing sustainable structures for aquaculture – that can be used on a commercial scale by producers. The prototype is currently being tested at the Olhão Fish Farming Pilot Station of the Portuguese Institute of the Sea and Atmosphere (IPMA), where this research also took place.

The study, published in the journal Applied Animal Behavior Science, was carried out by researchers from the Fish Etho Group (Faro), Algarve Marine Science Center (Faro), from the IPMA Olhão Fish Farming Pilot Station, the S2AQUA Collaborative Laboratory (Olhão) and the Mediterranean Institute of Advanced Studies – IMEDEA (Spain).

The Fish Etho Group is a non-profit association whose mission is to study and improve the well-being of aquatic animals. It bridges the gap between science and the aquaculture sector, applying cutting-edge scientific knowledge to best practices in both aquaculture and fisheries. It works directly with European Union bodies, national competent authorities from several EU Member States, large international companies and top research institutions.