Lower Columbia River Whitefish Life History and Egg Mat Monitoring Program: Year 5 Interpretive Report

Author: Golder Associates Ltd

This monitoring program was initiated in 2008 and was carried out over five years. This project is complete. The purpose of this monitoring program was to collect and refine data on the location, timing, and depth distribution of mountain whitefish spawning in the Lower Columbia River below Hugh L. Keenleyside Dam to improve the annual estimate of egg mortality. Specifically, the key objectives are to: a) improve the understanding of whitefish life history and reproductive ecology; b) document topographic characteristics of representative whitefish spawning locations; and, c) improve the understanding of seasonal changes in the distribution of eggs in the river channel.

MQ1: What is the spatial distribution of whitefish spawning activities in the lower Columbia and lower Kootenay rivers? Is there inter-annual variation in spawning habitat use? Is the spatial distribution of spawning locations associated with flow management?
MQ2: What are the physical and hydraulic characteristics of whitefish spawning and egg incubation habitats?
MQ3: What is the seasonal timing of whitefish spawning in the lower Columbia and lower Kootenay rivers? To what extent does the timing and intensity of spawning vary from year to year? Is the timing or intensity of spawning associated with flow management?
MQ4: What is the pattern of egg dispersal at spawning locations? What is the vertical distribution of eggs in the river channel? Is the spatial distribution of eggs related to flow management?
Year 5 (2013) Status for MQ1-4:
In all years examined, the upper Columbia River section provided the most extensively utilized Mountain Whitefish spawning habitat. Within this section, CPR Island and Kootenay River were identified as key spawning areas with consistently high rates of egg deposition. Tin Cup and Kinnaird Rapids were identified as secondary spawning areas where spawning occurs annually, but at a lower intensity than in the key spawning areas. Norns Creek was confirmed as a new secondary spawning area. Other, less extensively used sites were located in the middle or lower sections. Therefore, hypothesis H01 cannot be rejected but should be rephrased as follows: The distribution of key and secondary spawning areas used by Mountain Whitefish in the LCR does not differ significantly between years.
The habitat characteristics documented at the CPR Island and Kootenay River spawning areas in the present study are very similar to those recorded in the 1990s. Spawning in both areas occurred over predominantly cobble-boulder substrate. The range of depths at which egg deposition occurs at CPR Island was between approximately 1.0 m and 9.0 m depth in all study years examined. All egg deposition in the Kootenay River occurred between 0.5 m and 11.6 m depth. Mountain Whitefish spawning occurred between mean column water velocities of 0 m/s and 3.5 m/s in both key spawning areas. Secondary and low-use spawning sites in the middle and lower sections of the study area were only sampled during one spawning season; consequently, inter-year comparisons of physical and hydraulic characteristics in these areas could not be made. Therefore, based on the current dataset, hypothesis H02 cannot be rejected.
Similar to what was documented in the 1990s, present study results showed that Mountain Whitefish spawning at CPR Island consistently began between early and mid-November, peaked between early to mid-January, and was essentially completed by mid-February in all three spawning seasons surveyed. In the Kootenay River, Mountain Whitefish exhibited a consistent bimodal spawning pattern in all years. The initial peak occurred between mid-December and early January, while the subsequent peak occurred in mid-January. The onset and peak spawning periods in the key areas occurred over varying discharge patterns, which indicates that discharge was not the primary cue to initiate spawning or determine peak spawning. Therefore, based on the results of the present study, hypothesis H03 cannot be rejected.
Based on River 2D modelling as part of the CLBMON-47 program, the highest probability of egg deposition was between depths of 1.0 m to 4.5 m at CPR Island and between 3.0 m to 4.5 m.in the Kootenay River. Flow management affects water depth, water velocity patterns, and substrate type availability, which are all important determinants of spawning site selection by Mountain Whitefish. As water elevation and depth change within the key spawning area as a result of flow management, the locations of areas with preferred characteristics may shift as well. This could lead to spawners selecting differing areas to deposit eggs, resulting in differences in vertical distribution. However, given the highly localized and patchy egg distribution patterns observed at both key spawning sites and the relatively low inter-annual variability in flow during the spawning season, particularly in the Kootenay River, associations between egg deposition patterns and flow management could not be identified with the data available. Therefore, based on the current dataset, hypothesis H04 cannot be rejected.
MQ5: What are the pre-spawning and post-spawning seasonal movement patterns of Mountain Whitefish? How do sub-adult and adult migrations affect the interpretation of annual index monitoring programs?
The LRFIP indexing program only monitors abundance in the early fall period and has not identified trends that would suggest that sub-adults undergo significant migrations during that time. The present study focused on monitoring the migrations of adults during the pre-spawning period. An unknown proportion of adult Mountain Whitefish that reside in the lower, middle and upper section of the LCR undertake significant migrations to spawning areas in other sections of the river, prior to the peak spawning period. These movements may potentially introduce biases (e.g., violation of the HBM assumption of a closed population) and confound results of the LRFIP although how or to what degree is unclear. Therefore, H05 is accepted.
MQ6: What habitats are juvenile whitefish using in the lower Columbia and lower Kootenay rivers? Is it possible to develop and implement a reliable program for indexing the young-of-the-year abundance as a measure of fish coho salmonrt strength?
The largest numbers of larval and young-of-the-year (YOY) Mountain Whitefish were encountered in the upper section of the LCR in shallow, low velocity depositional habitats with fine substrates and a direct connection to the mainstem. YOY used these areas during the night but not during the day. Day time habitat use by YOY fish remains unknown. With low recapture rates, clumped distributions, and limitations of the capture methods and current telemetry technology, it is not possible to develop a reliable program to index YOY abundance in the LCR at this time. Therefore, hypothesis H06 is rejected.

MQ1: What is the spatial distribution of whitefish spawning activities in the lower Columbia and lower Kootenay rivers? Is there inter-annual variation in spawning habitat use? Is the spatial distribution of spawning locations associated with flow management?
MQ2: What are the physical and hydraulic characteristics of whitefish spawning and egg incubation habitats?
MQ3: What is the seasonal timing of whitefish spawning in the lower Columbia and lower Kootenay rivers? To what extent does the timing and intensity of spawning vary from year to year? Is the timing or intensity of spawning associated with flow management?
MQ4: What is the pattern of egg dispersal at spawning locations? What is the vertical distribution of eggs in the river channel? Is the spatial distribution of eggs related to flow management?
Year 5 (2013) Status for MQ1-4:
In all years examined, the upper Columbia River section provided the most extensively utilized Mountain Whitefish spawning habitat. Within this section, CPR Island and Kootenay River were identified as key spawning areas with consistently high rates of egg deposition. Tin Cup and Kinnaird Rapids were identified as secondary spawning areas where spawning occurs annually, but at a lower intensity than in the key spawning areas. Norns Creek was confirmed as a new secondary spawning area. Other, less extensively used sites were located in the middle or lower sections. Therefore, hypothesis H01 cannot be rejected but should be rephrased as follows: The distribution of key and secondary spawning areas used by Mountain Whitefish in the LCR does not differ significantly between years.
The habitat characteristics documented at the CPR Island and Kootenay River spawning areas in the present study are very similar to those recorded in the 1990s. Spawning in both areas occurred over predominantly cobble-boulder substrate. The range of depths at which egg deposition occurs at CPR Island was between approximately 1.0 m and 9.0 m depth in all study years examined. All egg deposition in the Kootenay River occurred between 0.5 m and 11.6 m depth. Mountain Whitefish spawning occurred between mean column water velocities of 0 m/s and 3.5 m/s in both key spawning areas. Secondary and low-use spawning sites in the middle and lower sections of the study area were only sampled during one spawning season; consequently, inter-year comparisons of physical and hydraulic characteristics in these areas could not be made. Therefore, based on the current dataset, hypothesis H02 cannot be rejected.
Similar to what was documented in the 1990s, present study results showed that Mountain Whitefish spawning at CPR Island consistently began between early and mid-November, peaked between early to mid-January, and was essentially completed by mid-February in all three spawning seasons surveyed. In the Kootenay River, Mountain Whitefish exhibited a consistent bimodal spawning pattern in all years. The initial peak occurred between mid-December and early January, while the subsequent peak occurred in mid-January. The onset and peak spawning periods in the key areas occurred over varying discharge patterns, which indicates that discharge was not the primary cue to initiate spawning or determine peak spawning. Therefore, based on the results of the present study, hypothesis H03 cannot be rejected.
Based on River 2D modelling as part of the CLBMON-47 program, the highest probability of egg deposition was between depths of 1.0 m to 4.5 m at CPR Island and between 3.0 m to 4.5 m.in the Kootenay River. Flow management affects water depth, water velocity patterns, and substrate type availability, which are all important determinants of spawning site selection by Mountain Whitefish. As water elevation and depth change within the key spawning area as a result of flow management, the locations of areas with preferred characteristics may shift as well. This could lead to spawners selecting differing areas to deposit eggs, resulting in differences in vertical distribution. However, given the highly localized and patchy egg distribution patterns observed at both key spawning sites and the relatively low inter-annual variability in flow during the spawning season, particularly in the Kootenay River, associations between egg deposition patterns and flow management could not be identified with the data available. Therefore, based on the current dataset, hypothesis H04 cannot be rejected.
MQ5: What are the pre-spawning and post-spawning seasonal movement patterns of Mountain Whitefish? How do sub-adult and adult migrations affect the interpretation of annual index monitoring programs?
The LRFIP indexing program only monitors abundance in the early fall period and has not identified trends that would suggest that sub-adults undergo significant migrations during that time. The present study focused on monitoring the migrations of adults during the pre-spawning period. An unknown proportion of adult Mountain Whitefish that reside in the lower, middle and upper section of the LCR undertake significant migrations to spawning areas in other sections of the river, prior to the peak spawning period. These movements may potentially introduce biases (e.g., violation of the HBM assumption of a closed population) and confound results of the LRFIP although how or to what degree is unclear. Therefore, H05 is accepted.
MQ6: What habitats are juvenile whitefish using in the lower Columbia and lower Kootenay rivers? Is it possible to develop and implement a reliable program for indexing the young-of-the-year abundance as a measure of fish coho salmonrt strength?
The largest numbers of larval and young-of-the-year (YOY) Mountain Whitefish were encountered in the upper section of the LCR in shallow, low velocity depositional habitats with fine substrates and a direct connection to the mainstem. YOY used these areas during the night but not during the day. Day time habitat use by YOY fish remains unknown. With low recapture rates, clumped distributions, and limitations of the capture methods and current telemetry technology, it is not possible to develop a reliable program to index YOY abundance in the LCR at this time. Therefore, hypothesis H06 is rejected.