Groundwater Habitat Interactions for Interior Fraser Coho


Year 2011
Proponent Secwepemc Fisheries Commission
Project type Habitat
FSWP funding source Living Rivers
Grant amount $15,000
Total project value $58,639
ID number FSWP11-LR35-H

Location: Thompson, Nicola, Lower Thompson, North Thompson, and South Thompson watershed

Project Summary

To find out about work on this project in other years, use search link above and enter the keywords "groundwater habitat interaction" (including the quotes)

SUMMARY

This study is a collaborative effort between First Nations, government, academia and non-profit organizations aimed at understanding the role of groundwater for the freshwater habitat needs of juvenile and adult Endangered Interior Fraser River Coho Salmon. Our findings will provide the basis for sound management strategies of groundwater resources in light of their importance for instream salmonid habitat.

DESCRIPTION

This is Year 5 of a multi-year study aimed at understanding the freshwater habitat needs of the Interior Fraser River Coho Salmon (Oncorhynchus kisutch), which has been designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Most research on Coho Salmon has been conducted on coastal populations. As a result, management decisions are frequently based on results from coastal studies, even though recent evidence suggests that life histories may differ substantially between coastal and interior Coho populations (McRae, 2009; Warren, 2010).
This study addresses two knowledge gaps identified in the “Conservation Strategy for Coho Salmon, Interior Fraser River Populations” (Interior Fraser Coho Recovery Team, 2006a): (1) determining what constitutes as important habitat for Interior Fraser Coho populations and (2) the relationship between, and the importance of, groundwater and surface water sources.
In past years this project has focused primarily on investigating whether groundwater upwelling areas in streams provide thermal refuge to juvenile Coho during periods of heat stress. In Year 5, we propose to expand the study to include juvenile winter habitat selection and the adult spawning life stage of Coho Salmon. This is intended to provide a comprehensive understanding of the role groundwater plays in the freshwater life history of Interior Fraser Coho Salmon. 
The goals for the final year of this study are:
1) To determine if juvenile Coho make preferential use of groundwater upwelling areas during periods of temperature stress
After several years of data collection, a sufficiently large dataset is now available to conduct a robust statistical analysis comparing Coho abundance in groundwater upwelling and control sites. No further data collection is proposed.

2) To determine how much groundwater flows into upwelling areas
This was an objective in the previous year but could not be completed due to difficulty installing the required equipment. Alternative methodology suitable for site-specific conditions has been identified in collaboration with UBC Okanagan. It is important to determine groundwater fluxes at the sites to verify that thermal refuge conditions are indeed caused by groundwater upwelling. While cooler temperatures observed at the sites are suggestive of groundwater inflows, it is not possible to establish a cause-and-effect relationship based on stream temperature observations alone (McGrath, 2010). The proposed methods will reveal the magnitude of groundwater fluxes that currently maintain thermal refuge conditions and will serve in establishing baseline conditions for future reference. Establishing a quantitative link between groundwater fluxes, thermal refuge conditions and salmonid use is critical for manifesting the importance of groundwater to salmonids, particularly in light of the current modernization of BC’s groundwater legislation.

3) To determine if juvenile Coho preferentially use groundwater sites for overwintering
Groundwater upwelling areas providing thermal refuge from heat stress can also provide refuge from freezing temperatures in the winter.  With several groundwater sites identified, extending the study to include overwintering conditions requires relatively low effort and cost. This will provide information on the benefits of groundwater inflows to the entire freshwater juvenile rearing life stage of Coho Salmon.

4) To assess the importance of groundwater in spawning site selection for Interior Fraser Coho
Recently published research (McRae, 2009) indicates that upwelling groundwater plays an important role in spawning site selection of Interior Fraser Coho Salmon.  Regional DFO stock assessment biologists have emphasized the importance of research initiatives that clarify the role of groundwater in spawning site selection on a larger spatial scale. Therefore, SFC is proposing to expand the project to include a component studying groundwater fluxes in Coho redd sites.  The methodology for this is partially the same as that suggested for goal 2) and therefore expertise gained could be utilized for both tasks. Including adult spawning site selection in this study enables us to characterize the role groundwater plays in the egg, fry, rearing and spawning life stages of Interior Fraser Coho.

OBJECTIVES

  • Determine if juvenile Coho make preferential use of groundwater upwelling areas during periods of temperature stress
  • Determine how much groundwater flows into upwelling areas
  • Determine if juvenile Coho preferentially use groundwater sites for overwintering
  • Assess the importance of groundwater in spawning site selection for Interior Fraser Coho

METHODS

Task 1) Statistical analysis of juvenile Coho catch per unit effort (CPUE)/m2 in groundwater and control sites will be conducted using repeated measures Analysis of Variance (ANOVA) in the statistical software package R. Additional independent variables will include instantaneous and ambient stream temperatures, depth, cover type and amount, habitat type, substrate size and embeddedness, and crown closure.  The analysis includes snorkel survey data from 2007 to 2009 and will verify if any preferential usage of groundwater sites can be clearly linked to lower temperatures rather than differences in habitat quality.  No additional data collection is required.

Task 2) Mini-piezometers constructed of polyethylene tubing will be inserted in the streambed at each of the 10 established groundwater sites using steel casing, a post pounder and a piece of rebar (Lee and Cherry, 1978). Manometers made of PVC tubing and a compressible bulb mounted on a metre stick (Lee and Cherry, 1978) will be used to measure the head difference between within-streambed and the stream necessary for calculating the vertical hydraulic gradient (VHG). Hydraulic conductivity (K) will be measured by slug testing based on Hvorslev’s (1951) method. During slug testing a known volume of water is removed from the piezometer and the recovery of the head is recorded over time. Groundwater flux (q) will then be calculated from: q = K x VHG (Darcy’s law).

Task 3) Temperature loggers will be installed at all previously identified groundwater and control sites (10 paired sites) to continuously monitor stream temperatures throughout the winter months (November to March).  Winter temperatures in the groundwater and control sites will be compared statistically (t-test) to determine whether groundwater sites provide moderated winter temperatures. Monthly sampling using minnow traps baited with salmon roe will be conducted (October-January) to determine if juvenile Coho preferentially use groundwater sites for overwintering. Statistical methods for this analysis will identical to those described in Task 1). Additional collection of habitat parameters is not required; however, measurements of water quality (DO, pH) will be taken during each sampling event to ensure suitable conditions for salmonids exist. 

Task 4) The study streams for this task include Louis and Lemieux creeks, the Deadman River, and the Coldwater River. All streams support sufficient coho escapements which ensures that enough redd sites can be identified. Site selection expenses will be nearly zero because our technicians are intimately familiar with Coho spawning sites in the study streams based on years of escapement surveys and DFO has offered to provide GPS coordinates of spawning sites. 
Groundwater fluxes immediately adjacent to confirmed Coho redds and an equal number of nearby unused but suitable redd sites (80 sites total) will be quantified using mini-piezometers (methodology described in Task 2) inserted into the streambed to the depth of a typical redd (30 cm). In addition, habitat parameters such as temperature, substrate size and embeddedness, flow velocity, depth, and stream morphology will be measured at all sites. Groundwater fluxes and habitat parameters between used and unused redd sites will then be compared statistically using Generalized Linear Mixed Modeling (logistic regression) in the software R (McRae, 2009). 

BENEFITS

This project addresses fresh water habitat limitations for Interior Fraser Coho identified in DFO’s Conservation Strategy for Coho Salmon (Oncorhynchus kisutch), Interior Fraser Populations.  Clearly identifying the importance of groundwater to Coho will support the conservation of this resource for fish needs. This project enables local First Nations communities to play a significant role in the conservation and management of Coho Salmon on which they depend.