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Mortality related to pancreas disease in N orwegian farmed s almonid fish, S almo salar L . and O ncorhynchus mykiss ( W albaum)
Author(s) -
Stormoen M,
Kristoffersen A B,
Jansen P A
Publication year - 2013
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.12060
Subject(s) - salmo , outbreak , biology , mortality rate , aquaculture , disease , fish mortality , rainbow trout , norwegian , demography , fishery , fish <actinopterygii> , medicine , virology , linguistics , philosophy , sociology
High mortality during the salmonid seawater phase is a continuous problem for the salmonid aquaculture industry, although the mortality levels show a large variation both in farms with a disease history and those without. We wanted to examine the mortality patterns in farms with pancreas disease ( PD ) and compare it to farms without this diagnosis. Further, we wished to investigate the factors influencing the maximum mortality in both groups. We examined data from all salmonid farms in N orway stocked after J anuary 2003 and slaughtered before D ecember 2007. In total, 1884 cohorts were included, and 150 of these were diagnosed with PD . We found that season accounted for more of the variation in mortality than water temperature in PD ‐positive cohorts and that infection pressure influenced the mortality in non‐ PD cohorts, suggesting outbreaks of disease that are not diagnosed. We also found that the mortality in PD cohorts decreased significantly from 2003 to 2007, suggesting that increased knowledge about PD and targeted actions have been effective. Our study further suggests that crude mortality figures may be of limited use when wanting to examine a particular disease and risk factors for increased mortality. We suggest farmers and legislation should turn to a more modern approach with cause‐specific mortality records.