Historical Population Structure of Central Valley Steelhead and Its Alteration by Dams

San Francisco Estuary and Watershed Science

Alice Low¹  Dennis McEwan¹  Sheila Greene²  Charles Hanson³  John G. Williams⁴  R. Bruce MacFarlane⁵  Steven T. Lindley⁵  Robert S. Schick⁵  Christina Swanson⁶  Bernard May⁷  Matthew Goslin⁸  Ethan Mora⁸  Aditya Agrawal⁸  Thomas E. Pearson⁸  James J. Anderson⁹ 

[1] California Department of Fish and Game;California Department of Water Resources;Hanson Environmental, Inc.;Independent Consultant;National Oceanic and Atmospheric Administration;The Bay Institute;University of California, Davis;University of California, Santa Cruz;University of Washington;

关键词: steelhead;    O. mykiss;    endangered species;    population structure;    dispersal;    habitat model;    dams;    Central Valley;   

DOI  :  

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown