| ID |
2771 |
| Citation |
Stiff, H.W., Hyatt, K.D., Hall, P., Finnegan, B., and Macintyre, D. 2015. Water temperature, river discharge, and adult Sockeye salmon migration observations in the Babine watershed, 1946-2014. Can. Manuscr. Rep. Fish. Aquat. Sci. 3053: vi + 169 p. |
| Organization |
DFO |
| URL |
http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs97-4-3053-eng.pdf |
| Abstract/Description or Keywords |
Historical meteorological and hydrological data were assembled to review the influence of changes in these environmental factors on patterns of adult Sockeye migration in the Babine River, British Columbia. Regional air temperature data collected from Environment Canada meteorological stations were statistically related to intermittent water temperature timeseries (2003-2014) recorded at the Babine fish fence to hind-cast daily water temperature in Babine River for 1910-2014. Flow data from two hydrometric stations in the Babine watershed were statistically-related to construct a continuous daily discharge time-series for 1945-2014. A stratified categorical frequency analysis of daily migration rates versus water temperature and flow conditions, lagged 0-7 days earlier, was used to discern the most likely combination of threshold values for temperature, discharge and associated time lags contributing to daily fence count variation. Exceedance analyses were applied to reconstructed environmental time-series to review trends in events beyond these thresholds for water temperature and flow co-variates. Though trending upward (0.2°C per decade) since 1908, summer air temperatures remain cool in this northern watershed. Estimated daily mean water temperatures during Sockeye migration are approximately 15°C. The frequency and duration of extreme flows in the Babine River rose over the past 2-3 decades, indicating increasing variability in seasonal discharge levels. Though elevated water temperatures are still infrequent and do not appear to be limiting Sockeye migration, the frequency and duration of periods of warmer air temperatures increased since the 1970s relative to previous decades, and consequently average summer water temperatures appear to be exceeding thresholds conducive to salmon migration more frequently and for longer periods of time since the 1990s. However, there are inherent uncertainties in estimated water temperatures due to insufficient highquality water temperature observations. The most consistent environmental impact on Sockeye migration was a delay in the start of significant migration past the fence due to initial high Babine River discharge levels: when high flows persisted into the migratory period, high migration rates were generally inhibited until daily mean discharge dropped below ~100-120 cms. A non-parametric statistical method was used to explore the possibility that a limiting factor for high migration rates existed downstream in the Babine River. Preliminary results suggest that water temperature and discharge conditions 5-6 days earlier are most highly associated with large changes in migration rates at the fence. |
| Information Type |
Report |
| Regional Watershed |
Skeena River |
| Sub-watershed if known |
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| Aquifer # |
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| Comments |
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| Project status |
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| Contact Name |
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