Historical Population Structure of Central Valley Steelhead and Its Alteration by Dams
Historical Population Structure of Central Valley Steelhead and Its Alteration by Dams
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中央山谷虹鳟的历史种群结构及其因水坝而发生的变化
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发表时间：
2006
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通讯作者：
John G. Williams
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作者：
S. Lindley;R. Schick;A. Agrawal;Matthew N. Goslin;T. E. Pearson;E. Mora;James J. Anderson;B. May;S. Greene;C. Hanson;A. Low;Dennis R. McEwan;R. B. MacFarlane;C. Swanson;John G. Williams
中央谷虹鳟的有效保护和恢复规划需要了解历史种群结构。我们使用多阶段建模方法描述了中央谷虹鳟进化上重要单位的历史结构。在第一阶段，我们使用基于环境包络（河流流量、梯度和温度）的栖息地模型来确定可能适合硬头鱼产卵和饲养的河段，该模型以数字高程模型和气候数据作为输入。我们确定了 151 个潜在适宜栖息地，其中溪流栖息地超过 10 公里，适宜栖息地总面积为 25,500 平方公里。然后，我们测量了栖息地斑块之间的距离，并将彼此相距 35 公里以内的斑块聚类成 81 个不同的栖息地斑块。出于恢复规划的目的，假设使用这 81 个斑块的鱼群是（或曾经是）独立的种群。考虑到 81 个栖息地区域之间的气候和海拔差异，表明中央谷虹鳟 ESU 内至少有四个主要分区，分别对应于萨克拉门托河流域、Suisun 湾地区支流、内华达山脉的圣华金支流以及流向圣河上游布埃纳维斯塔和图莱里盆地的低海拔溪流所界定的地理区域。 华金河。其中，萨克拉门托河流域似乎是虹鳟生产的主要来源。目前，无法通行的水坝阻止了 80% 的历史可用栖息地的进入，并阻止了约 38% 历史虹鳟种群的所有历史产卵栖息地。
Effective conservation and recovery planning for Central Valley steelhead requires an understanding of historical population structure. We describe the historical structure of the Central Valley steelhead evolutionarily significant unit using a multi-phase modeling approach. In the first phase, we identify stream reaches possibly suitable for steelhead spawning and rearing using a habitat model based on environmental envelopes (stream discharge, gradient, and temperature) that takes a digital elevation model and climate data as inputs. We identified 151 patches of potentially suitable habitat with more than 10 km of stream habitat, with a total of 25,500 km of suitable habitat. We then measured the distances among habitat patches, and clustered together patches within 35 km of each other into 81 distinct habitat patches. Groups of fish using these 81 patches are hypothesized to be (or to have been) independent populations for recovery planning purposes. Consideration of climate and elevation differences among the 81 habitat areas suggests that there are at least four major subdivisions within the Central Valley steelhead ESU that correspond to geographic regions defined by the Sacramento River basin, Suisun Bay area tributaries, San Joaquin tributaries draining the Sierra Nevada, and lower-elevation streams draining to the Buena Vista and Tulare basins, upstream of the San Joaquin River. Of these, it appears that the Sacramento River basin was the main source of steelhead production. Presently, impassable dams block access to 80% of historically available habitat, and block access to all historical spawning habitat for about 38% of the historical populations of steelhead.