Session Name: Ecology of Juvenile Salmon in the Nearshore
Presentation Title: Juvenile sockeye mortality and residence time in the Strait of Georgia and to northern Queen Charlotte Strait
Presenter Name: Erin L. Rechisky, Kintama Research Services, 10-1850 Northfield Rd,
Nanaimo BC V9S3B3, 250-729-2600 x224, erin.rechisky@kintama.com
David W. Welch, Kintama Research Services, 10-1850 Northfield Rd, Nanaimo BC V9S3B3,
250-729-2600 x223, david.welch@kintama.com
Aswea D. Porter, Kintama Research Services, 10-1850 Northfield Rd, Nanaimo BC V9S3B3,
250-729-2600 aswea.porter@kintama.com
Tim Clark, Australian Institute of Marine Science, PMB 3, Townsville MC Townsville 4810,
Queensland, Australia, +61-7-4753 4431, t.clark@aims.gov.au
Nathan B. Furey, Department of Forest and Conservation Sciences, University of British
Columbia, 2424 Main Mall, Vancouver, BC V6T1Z4, 604-822-1969, n.b.furey@gmail.com
Scott G. Hinch, Department of Forest and Conservation Sciences, University of British
Columbia, 2424 Main Mall, Vancouver, BC V6T1Z4 ,604-822-9377, scott.hinch@ubc.ca
Abstract:
Fraser River sockeye smolts were tagged with acoustic transmitters and tracked 400-1100 km in 2004-7 (Cultus Lake) and 2010-2013 (Chilko Lake). We estimated annual values of survival, daily marine survival rate and travel time from the mouth of the Fraser River to the northern Strait of Georgia (NSOG) detection array, and to the NSOG array to the array in
Queen Charlotte Strait (QCS; which includes the final 40 km of the SOG, Discovery Passage,
Johnstone Strait, and Queen Charlotte Strait). In six of eight years, daily survival rates were better in the SOG relative to the northern area. Measured mean travel time from the Fraser
River mouth to NSOG ranged between 11-19 days. To account for the northern portion of the SOG being included in the QCS estimates, we used the daily survival rate to the NSOG array to estimate survival in the final 40 km of the northern SOG. Estimated travel time extrapolated for the entire SOG (based on a measured rate of 0.97 body lengths s -1 ) ranged between 14-24 days and mean survival decreased from 69 to 63% after accounting for these additional migration days. Because tagged smolts were larger than the general population (to accommodate acoustic tags), and smaller smolts may therefore spend more time migrating through the SOG, we also estimated travel time for smaller sockeye smolts
(21-29 days on average) and survival based on the additional days in the SOG (~60%). But because daily survival rate was generally poorer in the north, when we repeated these calculations for smaller smolts from SOG to QCS, survival decreased from 50% to 37%.
Thus, while the Strait of Georgia is likely an important component of marine survival, it

may not be the only area to limit population productivity. Understanding survival processes north of the SOG may also be important for improving adult return rates.
Student Presenter? No
Presentation Type: Oral presentation only