Biofilters Ensure the Best Living Conditions for Salmon

RESEARCH: around the world smolt are almost exclusively produced at smolt farms with recycled water. This places a great requirement on the water quality, so that the salmon is provided with the best possible living conditions. The large expansions being made to smolt farms make it possible to produce ever larger smolt. This means that the period in which the salmon is to be in the sea decreases and may play a part in limiting, for instance, the timespan of the louse problem. Fiskaaling and Luna have set to work on a collaboration to develop knowledge on biofilters, water quality, and fish health at smolt farms.

In the last few years the Faroese aquaculture companies have carried out extensive construction of modern smolt farms. This has been done to increase production and, among other things, to produce larger smolt before they are released into the sea, and thereby to limit the timespan where viruses and lice are creating trouble and cause unnecessary mortality in the farmed salmon.

At the smolt farms it is absolutely necessary to have a well-functioning and stable system, which ensures a continuous and good quality of water and thereby better health and growth for the fish. In this system it is biofilters that purify the recycled water of waste products originating from the smolt themselves as well as from the feed.

In the biofilters it is the nitrifying and denitrifying bacteria that eliminate, for instance, ammonia, nitrate, and nitrite from the recycled water. The chemicals in question can in large quantities have a directly negative effect on the salmon and lead to declining health and stress; thereby increasing mortality. It is therefore absolutely necessary to ensure well-functioning and stable biofilters comprising beneficial bacteria, which are able to maintain a good water quality at the smolt farms.

A better knowledge of the bacterial culture in the biofilters – e.g. on bacterial composition and activity – can provide important insight into various conditions at the smolt farm affecting the biofilters. This can give farmers an opportunity to improve on procedures and to thereby develop the production.

This type of knowledge is, however, rather limited at the moment, and therefore staff at Fiskaaling’s iNova laboratory has begun work on research in this field in close collaboration with the industry. For instance, concrete work has begun, where Fiskaaling and Luna are collaborating on developing knowledge on biofilters, water quality, and fish health at smolt farms.

Should anyone wish to learn more about this, they are welcome to contact Elin Djurhuus Samuelsen, researcher at Fiskaaling, tel. no. +298 77 47 13.