Werkman M, Green D M, Munro L A, Murray A G, Turnbull J F
Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
Dis Aquat Organ. 2011 Aug 29;96(1):69-82. doi: 10.3354/dao02382.
Movement of live animals is a key contributor to disease spread. Farmed Atlantic salmon Salmo salar, rainbow trout Onchorynchus mykiss and brown/sea trout Salmo trutta are initially raised in freshwater (FW) farms; all the salmon and some of the trout are subsequently moved to seawater (SW) farms. Frequently, fish are moved between farms during their FW stage and sometimes during their SW stage. Seasonality and differences in contact patterns across production phases have been shown to influence the course of an epidemic in livestock; however, these parameters have not been included in previous network models studying disease transmission in salmonids. In Scotland, farmers are required to register fish movements onto and off their farms; these records were used in the present study to investigate seasonality and heterogeneity of movements for each production phase separately for farmed salmon, rainbow trout and brown/sea trout. Salmon FW-FW and FW-SW movements showed a higher degree of heterogeneity in number of contacts and different seasonal patterns compared with SW-SW movements. FW-FW movements peaked from May to July and FW-SW movements peaked from March to April and from October to November. Salmon SW-SW movements occurred more consistently over the year and showed fewer connections and number of repeated connections between farms. Therefore, the salmon SW-SW network might be treated as homogeneous regarding the number of connections between farms and without seasonality. However, seasonality and production phase should be included in simulation models concerning FW-FW and FW-SW movements specifically. The number of rainbow trout FW-FW and brown/sea trout FW-FW movements were different from random. However, movements from other production phases were too low to discern a seasonal pattern or differences in contact pattern.
活体动物的移动是疾病传播的一个关键因素。养殖的大西洋鲑（Salmo salar）、虹鳟（Onchorynchus mykiss）和褐鳟/海鳟（Salmo trutta）最初在淡水（FW）养殖场饲养；随后，所有的鲑鱼和部分鳟鱼会被转移到海水（SW）养殖场。通常，鱼类在淡水阶段以及有时在海水阶段会在养殖场之间转移。季节性以及不同生产阶段接触模式的差异已被证明会影响家畜疫情的发展过程；然而，这些参数在之前研究鲑科鱼类疾病传播的网络模型中并未被纳入。在苏格兰，农民需要登记鱼类进出其养殖场的移动情况；在本研究中，这些记录被用于分别调查养殖鲑鱼、虹鳟和褐鳟/海鳟每个生产阶段移动的季节性和异质性。与海水 - 海水（SW - SW）移动相比，鲑鱼的淡水 - 淡水（FW - FW）和淡水 - 海水（FW - SW）移动在接触数量和不同季节模式方面表现出更高程度的异质性。淡水 - 淡水移动在5月至7月达到峰值，淡水 - 海水移动在3月至4月以及10月至11月达到峰值。鲑鱼的海水 - 海水移动在一年中更为持续，养殖场之间的连接以及重复连接数量较少。因此，就养殖场之间的连接数量而言，鲑鱼的海水 - 海水网络可能被视为同质且无季节性。然而，在关于淡水 - 淡水和淡水 - 海水移动的模拟模型中应特别纳入季节性和生产阶段。虹鳟的淡水 - 淡水移动数量以及褐鳟/海鳟的淡水 - 淡水移动数量并非随机。然而，来自其他生产阶段的移动数量过低，无法辨别季节性模式或接触模式的差异。
