Models for mapping and forecasting infective pressure from salmon louse Lepeo phtheirus salmonis larvae are of major importance in the Norwegian government’s management of salmonid aquaculture. These models use site-reported temperature and number of eggproducing female adult lice present within cages to calculate how many lice eggs and larvae are released from individual farms. The reported temperature is critical in this calculation, as temperature influences both frequency of ‘spawnings’ and egg developmental time until hatching. Farms report temperature measured at 3 m depth, as defined by regulation. However, the salmon themselves, and therefore also the attached female lice and their eggs, often swim deeper to meet their preferred temperature within the water column. This study compares calculated lice egg production based on reported temperature at 3 m depth to calculated lice egg production based on a hydrodynamic ocean model of temperature stratification and salmon-preferred temperature in the modelled stratifications. The results clearly show that present legislated routines with farm site temperature measurements at 3 m depth lead to underestimation of egg and larvae production in winter and overestimation in summer for a range of sites. Future mitigating management and models of lice output should use the temperature measured or modelled for the depths the salmon predominantly occupy.

中文翻译：

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优化水产养殖中鲑鱼虱的估计释放量

用于绘制和预测鲑鱼虱 Lepeo phtheirus Salmonis 幼虫感染压力的模型在挪威政府的鲑鱼养殖管理中具有重要意义。这些模型使用现场报告的温度和笼子内存在的产卵雌性成年虱子的数量来计算从各个农场释放的虱子卵和幼虫的数量。报告的温度在此计算中至关重要，因为温度会影响“产卵”的频率和孵化前的卵发育时间。农场报告在 3 m 深度测量的温度，如法规所定义。然而，鲑鱼本身，以及附着的雌性虱子和它们的卵，通常会游得更深，以满足它们在水体中的首选温度。本研究比较了根据 3 m 深度报告的温度计算的虱卵产量与基于温度分层的流体动力学海洋模型和模拟分层中鲑鱼偏好温度的计算虱卵产量。结果清楚地表明，目前在 3 m 深度进行农场现场温度测量的立法程序导致对一系列现场的冬季卵和幼虫产量的低估和夏季的高估。未来减轻虱子的管理和模型应该使用针对鲑鱼主要占据的深度测量或建模的温度。结果清楚地表明，目前在 3 m 深度进行农场现场温度测量的立法程序导致对一系列现场的冬季卵和幼虫产量的低估和夏季的高估。未来减轻虱子的管理和模型应该使用针对鲑鱼主要占据的深度测量或建模的温度。结果清楚地表明，目前在 3 m 深度进行农场现场温度测量的立法程序导致对一系列现场的冬季卵和幼虫产量的低估和夏季的高估。未来减轻虱子的管理和模型应该使用针对鲑鱼主要占据的深度测量或建模的温度。