Three-dimensional migration behavior of juvenile salmonids in reservoirs and near dams

Xinya Li,Geoffrey A Mcmichael,Tao Fu,Zhiqun D Deng,Martin L Ahmann,Jayson J Martinez,Richard S Brown,John R Skalski,Richard L Townsend,Bradly A Trumbo,Jon F Renholds

doi:10.1038/s41598-018-19208-1

Abstract

To acquire 3-D tracking data on juvenile salmonids, Juvenile Salmon Acoustic Telemetry System (JSATS) cabled hydrophone arrays were deployed in the forebays of two dams on the Snake River and at a mid-reach reservoir between the dams. The depth distributions of fish were estimated by statistical analyses performed on large 3-D tracking data sets from ~33,500 individual acoustic tagged yearling and subyearling Chinook salmon and juvenile steelhead at the two dams in 2012 and subyearling Chinook salmon at the two dams and the mid-reach reservoir in 2013. This research investigated the correlation between vertical migration behavior and passage routes. The depth distributions of fish within the forebays of the dams were significantly different from fish passing the mid-reach reservoir. Fish residing deeper in the forebay tended to pass the dam using deeper powerhouse routes. This difference in depth distributions indicated that the depth distribution of fish at the mid-reach reservoir was not related to behaviors of fish passing through certain routes of the adjacent dams. For fish that were detected deeper than 17.5 m in the forebays, the probability of powerhouse passage (i.e., turbine) increased significantly. Another important finding was the variation in depth distributions during dam passage associated with the diel period, especially the crepuscular periods.

Highlights

Hydroelectric power production can result in mortality of turbine-passed fish due to several mechanisms[1]
To investigate the dependence of passage routes on depth distribution, the objectives of this study are answers to the following questions: 1) Are fish residing deeper in the forebay while approaching the dam more likely to pass through deeper routes? 2) Is the depth distribution of fish at a mid-reach reservoir related to the passage route depth at upstream or downstream dams? 3) What is the influence of diel period on depth distribution? 4) What is the probability of a fish detected at a specific location in the forebay and passing through a certain passage route? In this study we focus on presenting new results, as opposed to presenting new methods[28,29]
The subyearling Chinook salmon at the mid-reach reservoir tended to move at shallower depths in the water column than in the forebays at both Little Goose Dam (LGS) and Lower Monumental Dam (LMN) in 2013

Summary

Introduction

Hydroelectric power production can result in mortality of turbine-passed fish due to several mechanisms[1]. One of the related studies[28] provided methodology details of how acclimation depth was estimated and evaluated for individual fish at Little Goose Dam and Lower Monumental Dam (Fig. 1) prior to passage It focused only on the depth distribution of juvenile salmonids in the forebays prior to passage through turbines or the JBSs. The statistical analyses developed[28] were used to conduct pairwise comparisons of the depth distributions between sample groups in this research. We used a large set of 3-D fish track data from approximately 33,500 tagged juvenile salmonids (Oncorhynchus tshawytscha and Oncorhynchus mykiss) during the migration seasons of 2012 and 2013 Such a large data size helped to ensure that the sample size (related to precision) used in the statistical analyses was adequate when the sample groups in comparisons were classified according to species, year, location(dam or mid-reach reservoir), and diel period (day or night)

Objectives

Methods

Results

Discussion

Conclusion