Helth situation in farmed Norwegian fish 2009
Laks med Pseudomonas-infeksjon
Foto: Renate Johansen, Veterinærinstituttet
The health situation in farmed salmonids in Norway is relatively good, but there remain considerable losses as a result of many diseases, of both known and unknown cause. The existence of so many diseases of unknown cause, and the annual appearance of new diseases, make disease diagnostics especially challenging. There are no significant changes in the disease situation in farmed marine fish species. The majority of samples submitted are from cod, with the remainder from halibut, wrasse, turbot and other species.
In 2009, 856 000 tons (harvest statistics) of Atlantic salmon, along with an estimated 81 000 tons of rainbow trout, 19 600 tons of cod, 1800 tons of halibut and 1600 tons of other species e.g. coalfish, Arctic charr and halibut, were produced (Kontali Analyse AS). Production related losses remain significant, and a large proportion of these losses are related to disease.
Although we have good oversight of the diseases in Norwegian aquaculture, we lack knowledge relating to the overall losses caused by disease. That we have not managed to reduce these losses more than we have, is disturbing, and the industry faces a considerable challenge in this regard. Given the increased focus on fish health and more robust (in terms of fish health) production systems, it has been shown e.g. in the Faeroe Islands, that it is possible to further reduce these losses.
Pancreas Disease (PD) has been the dominant disease in salmon farming in recent years. Both the industry and the authorities have worked hard towards control of this disease. Despite registration of outbreaks outside the PD “core area”, fewer outbreaks, with lower overall losses provide grounds for optimism. Although the number of infectious salmon anaemia (ISA) outbreaks is also considerably lower than previously, a core area for this disease still exists in Northern Norway.
The major fish health challenge during 2009 was that of salmon lice infestation. Problems of reduced sensitivity and development of resistance to treatment have increased and as a consequence large numbers of lice were recorded throughout the autumn. Successful salmon louse treatment is dependent on coordinated control strategies requiring extensive cooperation throughout the Norwegian aquaculture industry.
While new medications are necessary, they will only provide a breathing space for establishment of other sustainable control strategies. Increased use of wrasse will constitute an important element in such strategies, but will also increase the possibility of other types of disease and disease transmission. Although a vaccine should be an important element in salmon louse control in the longer term, there remains much uncertainty related to both developmental time and effect.
”New” diseases will always present a challenge. In some cases, established diseases may change and present in new form. It is therefore important to maintain surveillance, follow trends and continually evaluate the importance of new research data.
Read the report "Health situation in Farmed Fish in Norway 2009"
Kontaktpersoner Veterinærinstituttet:
Brit Hjeltnes, Departemental Director, Department for Fish and Shellfish Health
Phone.: 55 36 38 24/918 89 376
E-mail: brit.hjeltnes@vetinst.no
Geir Bornø, National Veterinary Institute, Harstad
Phone.: 77 04 15 69/911 16 649
E-mail: geir.borno@vetinst.no
