Centre of Epidemiology and Biostatistics, Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Oslo, Norway.
J Fish Dis. 2013 Jul;36(7):639-45. doi: 10.1111/jfd.12060. Epub 2013 Jan 13.
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 Norway stocked after January 2003 and slaughtered before December 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.
在鲑鱼养殖业中，鲑鱼在进入海水养殖阶段后的高死亡率一直是一个持续存在的问题，尽管死亡率在有疾病史的养殖场和无疾病史的养殖场之间存在很大差异。我们希望研究患有胰腺疾病（PD）的养殖场的死亡率模式，并将其与没有这种诊断的养殖场进行比较。此外，我们还希望研究影响这两个群体最大死亡率的因素。我们检查了 2003 年 1 月以后放养和 2007 年 12 月以前屠宰的所有挪威鲑鱼养殖场的数据。总共包括了 1884 个批次，其中 150 个被诊断为患有 PD。我们发现，在 PD 阳性批次中，季节对死亡率的影响大于水温，而在非 PD 批次中，感染压力对死亡率有影响，这表明存在未被诊断出的疾病爆发。我们还发现，PD 批次的死亡率从 2003 年到 2007 年显著下降，这表明对 PD 的认识不断提高和有针对性的行动已经产生了效果。我们的研究进一步表明，当想要检查特定疾病和增加死亡率的风险因素时，粗略的死亡率数据可能用处有限。我们建议农民和立法者应该采用更现代的方法，记录特定原因的死亡率。
