The Norwegian Veterinary Institute, PB. 750 Sentrum, N-0106 Oslo, Norway.
Uni Research Environment, LFI-Freshwater Biology, Nygårdsporten 112, N-5006 Bergen, Norway.
Epidemics. 2018 Jun;23:19-33. doi: 10.1016/j.epidem.2017.11.001. Epub 2017 Dec 2.
The Norwegian government recently implemented a new management system to regulate salmon farming in Norway, aiming to promote environmentally sustainable growth in the aquaculture industry. The Norwegian coast has been divided into 13 production zones and the volume of salmonid production in the zones will be regulated based on salmon lice effects on wild salmonids. Here we present a model for assessing salmon louse-induced mortality of seaward-migrating post-smolts of Atlantic salmon. The model quantifies expected salmon lice infestations and louse-induced mortality of migrating post-smolt salmon from 401 salmon rivers draining into Norwegian coastal waters. It is assumed that migrating post-smolts follow the shortest path from river outlets to the high seas, at constant progression rates. During this migration, fish are infested by salmon lice of farm origin according to an empirical infestation model. Furthermore, louse-induced mortality is estimated from the estimated louse infestations. Rivers draining into production zones on the West Coast of Norway were at the highest risk of adverse lice effects. In comparison, rivers draining into northerly production zones, along with the southernmost production zone, were at lower risk. After adjusting for standing stock biomass, estimates of louse-egg output varied by factors of up to 8 between production zones. Correlation between biomass adjusted output of louse infestation and densities of farmed salmon in the production zones suggests that a large-scale density-dependent host-parasite effect is a major driver of louse infestation rates and parasite-induced mortality. The estimates are sensitive to many of the processes in the chain of events in the model. Nevertheless, we argue that the model is suited to assess spatial and temporal risks associated with farm-origin salmon lice.
挪威政府最近实施了一项新的管理系统，以规范挪威的三文鱼养殖，旨在促进水产养殖业的环境可持续增长。挪威海岸已被划分为 13 个生产区，根据鲑鱼虱对野生鲑鱼的影响，这些区域的鲑鱼养殖量将得到调节。在这里，我们提出了一个评估洄游性大西洋三文鱼幼鱼感染鲑鱼虱后死亡率的模型。该模型量化了从 401 条流入挪威沿海水域的三文鱼河流洄游性幼鱼的预期鲑鱼虱感染和鲑鱼虱引起的死亡。假设洄游性幼鱼沿最短路径从河流出口向公海前进，以恒定的进展速度。在这个迁移过程中，鱼类会根据经验感染来自养殖场的鲑鱼虱。此外，根据估计的虱感染情况来估计虱引起的死亡率。流入挪威西海岸生产区的河流面临着最严重的虱危害风险。相比之下，流入北部生产区以及最南部生产区的河流风险较低。在对存量生物量进行调整后，虱卵产量的估计值在生产区之间的差异可达 8 倍。虱感染的生物量调整后输出量与生产区养殖三文鱼密度之间的相关性表明，大规模的密度依赖宿主-寄生虫效应是虱感染率和寄生虫引起的死亡率的主要驱动因素。这些估计值对模型中事件链的许多过程都很敏感。尽管如此，我们认为该模型适合评估与养殖场来源的鲑鱼虱相关的空间和时间风险。
