Using a forward projecting population model, the timing and scale of Lake Sturgeon Acipenser fulvescens (LS) recovery and natural reproduction was estimated for the Milwaukee River in Wisconsin, USA for the years 2004–2048. LS, a widely distributed potamodromous Acipenseridae species in North America, have, like other sturgeon species, suffered population declines due to overharvest and other factors since the 1800s. LS recovery efforts were initiated in the early 1980s following the successful development of LS propagation techniques and stocking has become a widely utilized tool in LS recovery programs. Sturgeon recovery programs are long-term endeavors, with annual stocking usually planned for 25 plus years, along with population assessments and habitat improvements conducted over decades before project success can be verified. LS recovery activities on the Milwaukee River, a Lake Michigan tributary in southeast Wisconsin, began with barrier mitigation in 1997 and stocking in 2003. The modest size of the Milwaukee River, along with habitat improvements, and 17 years of stocking, provided an opportunity to model and predict LS population recovery trends. A forward projecting population model with an imbedded stochastic Ricker stock-recruitment relationship, adjusted for the estimated LS productive capacity of the Milwaukee River, estimated the timing and scale of LS recovery during 2004–2048 predicting a 18.3% annual average population rate of increase during the stocking period, and a 5.7% post-stocking rate. Accelerated LS growth and maturity due to goby consumption built into the model resulted in projections of gravid adult males present in 2012 and spawning adult females and natural recruitment in 2019. During the 2020 spawning period a group of adult-sized LS were observed in the Milwaukee River below an intermittent barrier on the river. The model predicted adult LS densities to grow from 22 in 2012 to 8088 in 2048, and annual natural recruitment to grow steadily from 76 yearlings in 2019 to an average of 4000 yearlings/year during 2039-2049. The estimated number of yearling recruits per spawning (gravid) female dropped steadily from 21 in 2019 to 8 recruits per gravid female in 2048 as a function of the Ricker stock-recruitment relationship built into the model. The model results indicate that significant LS recovery can possibly begin in a shorter time frame on Great Lakes tributaries than originally expected through systematic resolution of habitat issues and LS stocking. Results can also be used to help anticipate recovery trends, fine tune stocking and habitat strategies, and plan LS recovery assessments.

中文翻译：

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美国威斯康星州密尔沃基河的湖鲟预计恢复

使用前向投影种群模型，Lake Sturgeon Acipenser fulvescens的时间和规模2004-2048 年美国威斯康星州密尔沃基河的 (LS) 恢复和自然繁殖估计。LS 是北美广泛分布的一种鲟科鲟科物种，自 1800 年代以来，与其他鲟鱼物种一样，由于过度捕捞和其他因素，种群数量下降。随着 LS 繁殖技术的成功发展，LS 恢复工作于 1980 年代初期开始，放养已成为 LS 恢复计划中广泛使用的工具。鲟鱼恢复计划是一项长期的工作，通常计划每年放养 25 年以上，并在验证项目成功之前进行了数十年的种群评估和栖息地改善。在威斯康星州东南部密歇根湖支流密尔沃基河上的 LS 恢复活动，始于 1997 年的障碍缓解和 2003 年的放养。密尔沃基河的适度规模，随着栖息地的改善，以及 17 年的放养，为模拟和预测 LS 种群恢复趋势提供了机会。具有嵌入的随机 Ricker 库存-招聘关系的前向预测人口模型，根据密尔沃基河的估计 LS 生产能力进行了调整，估计了 2004-2048 年期间 LS 恢复的时间和规模，预测期间人口年平均增长率为 18.3%放养期，放养后5.7%。由于模型中内置的虾虎鱼消费导致 LS 生长和成熟加速，导致预测 2012 年出现妊娠成年雄性，并在 2019 年产卵成年雌性和自然补充。在 2020 年的产卵期，在密尔沃基河的间歇性屏障下方观察到了一群成年 LS。该模型预测成年 LS 密度将从 2012 年的 22 头增加到 2048 年的 8088 头，并且每年自然招募的数量将从 2019 年的 76 羽一岁鸽稳步增长到 2039-2049 年期间的平均 4000 羽一岁鸽。由于模型中内置的 Ricker 种群 - 招募关系，每个产卵（妊娠）雌性的一岁鸽新兵估计数量从 2019 年的 21 名稳步下降到 2048 年每名怀孕雌性的 8 名新兵。模型结果表明，通过系统地解决栖息地问题和 LS 放养，五大湖支流的显着 LS 恢复可能会在比最初预期的更短的时间内开始。结果还可用于帮助预测恢复趋势，