Journal of Fish Biology (2011) 78, 1976–1992 doi:10.1111/j.1095-8649.2011.02971.x, available online at wileyonlinelibrary.com Residency time, migration route and survival of Atlantic salmon Salmo salar smolts in a Canadian fjord J. B. Dempson*†, M. J. Robertson*, C. J. Pennell*, G. Furey*, M. Bloom*, M. Shears*, L. M. N. Ollerhead*, K. D. Clarke*, R. Hinks‡ and G. J. Robertson§ *Fisheries and Oceans Canada, Science Branch, P. O. Box 5667, St. John’s, NL, A1C 5X1 Canada, ‡Miawpukek Mi’kamawey Mawi’omi, P. O. Box 10, Conne River, NL, A0H 1J0 Canada and §Environment Canada, Wildlife Research Division, 6 Bruce Street, Mount Pearl, NL, A1N 4T3 Canada (Received 20 July 2010, Accepted 2 March 2011) Atlantic salmon Salmo salar smolts (n = 181) from two rivers were surgically implanted with acoustic transmitters and released to determine migration route, residency time and survival in a 50 km long estuarine fjord located on the south coast of Newfoundland, Canada. Data obtained from automated receivers placed throughout the Bay d’Espoir fjord indicated that migrating smolts used different routes to reach the outer areas of the fjord. The duration of time that smolts spent in the immediate estuary zone also differed between the two localities (7 and 17 days) although the total time smolts were resident in the fjord was similar and extensive (40 days). Many smolts were resident for periods of 4–8 weeks moving back and forth in the outer part of the fjord where maximum water depths range from 300 to 700 m. Survival in the estuary zone was greater for smolts with prolonged residency in estuarine habitat. Overall smolt survival to the fjord exit was moderately high (54–85%), indicating that the initial phase of migration did not coincide with a period of unusually high mortality.  2011 Crown Copyright Journal of Fish Biology  2011 The Fisheries Society of the British Isles Key words: acoustic telemetry; capture – mark – recapture; distribution; Newfoundland; Program MARK. INTRODUCTION It is commonly believed that factors responsible for the decline in the survival and abundance of Atlantic salmon Salmo salar L. 1758 in recent decades operate primar- ily in the marine environment (Friedland et al., 1993, 2009; Ritter, 1993; Friedland, 1998; Hawkins, 2000; Potter & Crozier, 2000; Reddin et al., 2000; Montevecchi et al., 2002; Jonsson & Jonsson, 2004; McCarthy et al., 2008). Cairns (2001) pro- vided a semi-quantitative approach that placed 10 of the top 12 factors potentially associated with the decline of S. salar in estuarine or marine areas. Much of the mor- tality that occurs have also been attributed to a critical period when smolts first enter the marine environment (Tytler et al., 1978; Friedland et al., 1998; Hansen & Quinn, †Author to whom correspondence should be addressed. Tel.: +1 709 772 4475; email: brian.dempson@ dfo-mpo.gc.ca 1976  2011 Crown Copyright Journal of Fish Biology  2011 The Fisheries Society of the British Isles