Evira's fish disease research supports blue bio-economy

9.3.2016

<p>New techniques in fish farming, such as recirculation aquaculture systems and enriched rearing create new challenges for fish health care. The research carried out by Finnish Food Safety Authority Evira on fish diseases supports blue bio-economy, as it provides necessary scientific data on the behaviour of fish pathogens specifically in Finnish conditions. Broadly speaking, blue bio-economy covers all resources related to water and waterways.&nbsp;</p>

The predominantly cool weather in the summer of 2015 kept water temperatures ideal for aquaculture in Finland. This is particularly reflected in the low number of cases of diseases caused by bacteria.

”The good status with respect to bacterial diseases could be seen especially in the extremely low consumption of antibiotic feeds”, says Researcher Satu Viljamaa-Dirks from the Production Animal and Wildlife Health Research Unit.

Vigilance is needed due to viral diseases

Infectious Pancreatic Necrosis (IPN) is a good example of a disease that gains ground quickly, if measures to combat the disease are no longer implemented. The virus was in 2015 isolated as many as 25 times, while a few years back it was usually found in less than ten farms each year.

”We have not been able to establish the transmission route of the disease to inland. It is quite possible, and even probable, that the same route is still in place and the risk of more aggressive pathogens finding their way to hatcheries is high”, Viljamaa-Dirks concludes.

Efficient and reliable research on fish diseases

A large number of polymerase chain reaction methods, or PCR methods, have been developed for the identification of fish pathogens. These methods are tools based on molecular biology, used to analyse samples for pathogens such as viruses, bacteria, fungi or parasites.

”PCR methods have in some parts replaced more conventional methods, such as virus and bacteria culture methods. The advantages of PCR methods include speed and accuracy. In addition, these methods can identify pathogens that are difficult or impossible to culture”, explains Special Researcher Riikka Holopainen, PhD, from the Veterinary Virology Research Unit.

PCR methods are also utilised to monitor diseases or to demonstrate the absence of a certain disease in Finnish conditions.

Recirculation aquaculture systems for sustainable fish production

Food-grade fish are already imported into Finland to a value of more than 300 Million Euro per year. The quickest way to meet the increased demand is through farmed fish production; it is also one of the most sustainable ways to produce protein of animal origin.

Recirculation aquaculture systems use only a fraction of the amount of water needed in conventional farming techniques.

”Factors that are significant in terms of fish health concern the possibilities to regulate ambient conditions. These include e.g. the possibility to purify and disinfect the supply water, as well as efficient control and management of water quality and temperature. The challenges related to recirculation aquaculture systems pertain to high fish densities as well as rapid and continuous growth”, says Researcher Anna Maria Eriksson-Kallio from the Production Animal and Wildlife Health Research Unit.

Enriched rearing can reduce susceptibility of farmed fish to infectious diseases

The aim of enriched rearing is to provide farmed fish an environment that imitates the variations in natural conditions.

”In the best case, this can improve the survival of fish stocked into the wild. There have also been indications suggesting that the welfare of fish can be influenced by adding shelters in the tanks and changing irregularly the water inflow, volume and direction of water circulation. Improved welfare translates into less need for care and lower mortality due to diseases”, says Päivi Rintamäki, PhD, Docent, from the University of Oulu.

Researchers and operators of the fish farming industry will be brought together in the annual Fish Health Day organised by Evira and the Association of Finnish Professional Fishermen (Suomen Ammattikalastajaliitto) on 11 March 2016 in connection with the Fish Week Event.

Read more on

Evira's news release on recirculation aquaculture systems 301.2015

Blue bio-economy

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