Keefer Matthew L, Clabough Tami S, Jepson Michael A, Bowerman Tracy, Caudill Christopher C
Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, 875 Perimeter Drive MS 1136, Moscow, ID 83844-1136, USA.
Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, 875 Perimeter Drive MS 1136, Moscow, ID 83844-1136, USA.
J Therm Biol. 2019 Jan;79:155-165. doi: 10.1016/j.jtherbio.2018.12.011. Epub 2018 Dec 11.
River warming poses an existential threat to many Pacific salmon (Oncorhynchus spp) populations. However, temperature-mediated risks to salmon are often complex and addressing them requires species- and population-specific data collected over large spatial and temporal scales. In this study, we combined radiotelemetry with archival depth and temperature sensors to collect continuous thermal exposure histories of 21 adult spring- and summer-run Chinook salmon (O. tshawytscha) as they migrated hundreds of kilometers upstream in the Columbia River basin. Salmon thermal histories in impounded reaches of the Columbia and Snake rivers were characterized by low daily temperature variation but frequent and extensive vertical movements. Dives were associated with slightly cooler salmon body temperatures (~ 0.01 to 0.02 °C/m), but there was no evidence for use of cool-water thermal refuges deep in reservoirs or at tributary confluences along the migration route. In tributaries, salmon were constrained to relatively shallow water, and they experienced ~ 2-5 °C diel temperature fluctuations. Differences in migration timing and among route-specific thermal regimes resulted in substantial among-individual variation in migration temperature exposure. Bioenergetics models using the collected thermal histories and swim speeds ranging from 1.0 to 1.5 body-lengths/s predicted median energetic costs of ~ 24-40% (spring-run) and ~ 37-60% (summer-run) of initial reserves. Median declines in total mass were ~ 16-24% for spring-run salmon and ~ 19-29% for summer-run salmon. A simulated + 2 °C increase in water temperatures resulted in 4.0% (spring-run) and 6.3% (summer-run) more energy used per fish, on average. The biotelemetry data provided remarkable spatial and temporal resolution on thermal exposure. Nonetheless, substantial information gaps remain for the development of robust bioenergetics and climate effects models for adult Chinook salmon.
河流升温对许多太平洋鲑鱼（Oncorhynchus spp）种群构成了生存威胁。然而，温度对鲑鱼造成的风险往往很复杂，应对这些风险需要在大空间和时间尺度上收集特定物种和种群的数据。在本研究中，我们将无线电遥测与存档深度和温度传感器相结合，收集了21条成年春季和夏季洄游的奇努克鲑（O. tshawytscha）在哥伦比亚河流域向上游迁徙数百公里过程中的连续热暴露历史。哥伦比亚河和斯内克河蓄水河段的鲑鱼热历史特征是日温度变化小，但垂直移动频繁且范围广。潜水与鲑鱼体温略低（约0.01至0.02°C/米）有关，但没有证据表明它们利用水库深处或洄游路线上支流交汇处的冷水热避难所。在支流中，鲑鱼被限制在相对较浅的水域，它们经历约2 - 5°C的昼夜温度波动。洄游时间和特定路线热状况的差异导致个体间在迁徙温度暴露方面存在很大差异。使用收集到的热历史和1.0至1.5体长/秒的游速的生物能量学模型预测，春季洄游鲑鱼的能量消耗中位数约为初始储备的24 - 40%，夏季洄游鲑鱼为37 - 60%。春季洄游鲑鱼的总质量中位数下降约16 - 24%，夏季洄游鲑鱼为19 - 29%。水温模拟升高2°C导致每条鱼平均多消耗4.0%（春季洄游）和6.3%（夏季洄游）的能量。生物遥测数据提供了关于热暴露的出色时空分辨率。尽管如此，在为成年奇努克鲑鱼开发强大的生物能量学和气候影响模型方面，仍存在大量信息空白。
