Flavobacterium psychrophilum can be a significant mortality source in hatcheries where trout and salmon (Family Salmonidae) are propagated and raised. Preventing F. psychrophilum outbreaks and controlling its spread in hatcheries is challenged by limited effectiveness of current therapeutics and lack of efficacious commercial vaccines. Consequently, one of the few available options to limit outbreaks and spread within a facility may be modifications to hatchery-rearing practices. We developed an individual-based model to evaluate how rearing practices could limit F. psychrophilum-induced losses of Oncorhynchus mykiss in flow-through, partial-reuse raceway systems. Evaluated practices included frequency of removal of dead individuals, the probability that hatchery personnel found fish that died from infection, and water flow rate through raceways. Practices were assessed under different assumptions about initial number of infected individuals and virulence levels associated with infection. Increasing the frequency of removal of dead individuals led to the largest reductions in cumulative mortality due to disease as well as reductions in peak daily infection rates and time until peak daily infections occurred when compared to changes in flow rates. Under high initial infection, high virulence, and low flow conditions, increasing the frequency of removal from once to two or three times per day decreased cumulative mortality by approximately 150 thousand fish. When initial infection prevalence was high, disease outbreaks were acute with peak daily infection rates occurring 39 to 53 days post-placement in outdoor raceways. Conversely, when initial infection prevalence was low, infection course was more chronic. Increasing the frequency of dead fish removal to hourly and the probability of hatchery personnel finding dead fish in raceways when checks were performed resulted in modest gains in survival, although these results were likely conditional on model assumptions. If the probability of hatchery personnel finding dead fish was lower than what was assumed in our evaluations, larger gains from more frequently checking for dead fish may have resulted. We believe there is considerable potential in using simulation models to explore the benefits of different rearing practices in cultured fish. To that end, we have made the simulation model used in this study available for those interested in adapting or expanding it to address other research questions.

在繁殖和饲养鳟鱼和鲑鱼（鲑科）的孵化场中，嗜冷黄杆菌可能是一个重要的死亡率来源。预防嗜冷梭菌爆发和控制其在孵化场的传播受到当前治疗方法有效性有限和缺乏有效的商业疫苗的挑战。因此，限制设施内爆发和传播的少数可用选项之一可能是修改孵化场的饲养实践。我们开发了一个基于个体的模型来评估饲养实践如何限制F. psychrophilum引起的Oncorhynchus mykiss损失在流通式、部分重复使用的管道系统中。评估的做法包括清除死亡个体的频率、孵化场人员发现因感染而死亡的鱼的可能性以及通过水道的水流速。在关于感染个体的初始数量和与感染相关的毒力水平的不同假设下评估实践。与流速的变化相比，增加清除死者的频率可以最大程度地降低因疾病引起的累积死亡率，并减少每日感染高峰率和每日感染高峰发生的时间。在高初始感染、高毒力和低流量条件下，将清除频率从每天一次增加到两到三次，可使累积死亡率降低约 15 万条鱼。当最初的感染流行率很高时，疾病暴发是急性的，在室外跑道放置后 39 至 53 天出现每日感染率高峰。相反，当初始感染率较低时，感染过程更为慢性。将死鱼清除频率提高到每小时一次，以及在进行检查时孵化场人员在水道中发现死鱼的可能性会导致存活率略有提高，尽管这些结果可能以模型假设为条件。如果孵化场人员发现死鱼的概率低于我们评估中的假设，则可能会通过更频繁地检查死鱼而获得更大的收益。我们相信使用模拟模型来探索不同养殖方式对养殖鱼类的益处具有相当大的潜力。为此，