Spatio-temporal migration patterns of Pacific salmon smolts in rivers and coastal marine waters (original) (raw)
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Conservation physiology, 2016
The Bras d'Or Lake watershed of Cape Breton Island, Nova Scotia, Canada is a unique inland sea ecosystem, UNESCO Biosphere Reserve and home to a group of regionally distinct Atlantic salmon (Salmo salar) populations. Recent population decreases in this region have raised concern about their long-term persistence. We used acoustic telemetry to track the migrations of juvenile salmon (smolts) from the Middle River into the Bras d'Or Lake and, subsequently, into the Atlantic Ocean. Roughly half of the tagged smolts transited the Bras d'Or Lakes to the Atlantic Ocean, using a migration route that took them through the Gulf of St Lawrence's northern exit at the Strait of Belle Isle (∼650 km from the home river) towards feeding areas in the Labrador Sea and Greenland. However, a significant fraction spent >70 days in the Lakes, suggesting that this population has an alternative resident form, in which smolts limit their migrations within the Bras d'Or. Smolts in goo...
Freshwater Biology, 2020
Atlantic salmon (Salmo salar) smolts are often stocked into rivers to supplement natural reproduction, yet hatchery‐reared fish have lower survival compared to wild conspecifics. However, few studies have assessed riverine migratory performance and survival differences in hatchery and wild smolts, or more specifically naturally reared smolts (hatchery fish released earlier as parr), particularly in rivers with weirs which may further reduce survival. Using acoustic telemetry, including a subset of fish with novel transmitters that identify predation events, we assessed survival and migration patterns of hatchery‐ (2017: n = 32; 2018: n = 30) and naturally reared Atlantic salmon smolts (2017: n = 8; 2018: n = 30) in a Lake Ontario tributary with two weirs to better understand their ecology and assess the influence of environmental parameters on migration. Naturally reared smolts were 13.9 times more likely to survive than hatchery‐reared smolts and mark–recapture models indicated tha...
Coastal marine and in-river migration behaviour of adult sockeye salmon en route to spawning grounds
Marine Ecology Progress Series, 2014
Although behaviour and physiology of the reproductive migration of Pacific salmon Oncorhynchus spp. have been studied for the upriver migration, equivalent information for the coastal marine migratory phase has been difficult to obtain. Acoustic acceleration transmitters equipped with pressure sensors provide a tool to study swimming activity and migration depth of salmon in both marine and fresh water. Ocean migrating sockeye salmon O. nerka bound for the Fraser River, British Columbia (Canada), were intercepted approximately 200 km from the river entrance, tagged and tracked as they crossed several acoustic receiver lines in coastal waters and the lower Fraser River. Acceleration data were converted to swim speed using an existing statistical model. Data from 55 tagged fish revealed that swim speed and depth varied among migratory locales. Migration difficulty (freshwater migration distance and elevation to natal stream) was related to swim speed in the marine environment. Some of the variability in swim speed and depth was explained by diel and tidal cycles. In the marine environment, average (± SEM) swim speed estimate was ~1.23 body lengths (BL) s −1 at an average depth of 13 ± 0.058 m (range = 0−171 m), whereas the average swim speed in the river was significantly higher at ~1.57 BL s −1 at an average (± SEM) depth of ~9 ± 0.018 m (range = 0−21 m). Consistent with the physiological literature, coastal migrating fish were swimming near metabolically optimal speeds (0.9−1.2 BL s −1). Overall this study demonstrates that using acoustic accelerometer transmitters can provide valuable insights into behaviour of homing sockeye salmon in both marine and freshwater environments.
Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science, 2017
While Pacific salmon are known for their extensive marine migrations, some species display much more limited alternative patterns, including residence within interior marine waters. To more clearly define the scale of movement of these residents, we used acoustic telemetry to track subadult Chinook Salmon Oncorhynchus tshawytscha caught in and released from discrete areas of the Salish Sea. Their movements were determined from detections at fixed receivers in central Puget Sound, Admiralty Inlet, the San Juan Islands, and the Strait of Juan de Fuca. Cluster analysis of the detections indicated four groups, with much less commonality of movement than might be inferred from the proximity of the tagging locations, which were only tens of kilometers apart. For example, none of the salmon tagged in central Puget Sound were detected in the San Juan Islands and vice versa. Thus, Chinook Salmon occupying central Puget Sound and the San Juan Islands may exhibit different distributions, extents of movement, and degrees of basin fidelity. These results provide information relevant to the management and conservation of this species, which is listed as threatened under the U.S. Endangered Species Act, and whose movements cross the U.S.-Canadian boundary. These findings may also help explain the variation in organic contaminant levels among Puget Sound-origin Chinook Salmon. Migratory behavior is widely distributed among animal taxa, playing a central role in their ecology, evolution (Baker 1978; Dingle 1996), and population dynamics (Morales et al. 2010). Migration plays an important role in ecosystem processes and conservation because it can link habitats with the transfer of nutrients, disease, and contaminants (Bauer and Hoye 2014). Among fishes, Atlantic and Pacific salmon are famous for the great distances that they travel at sea and upriver. However,
Canadian Journal of Fisheries and Aquatic Sciences, 2009
Freshwater and early marine migration and survival of endangered Cultus Lake sockeye ( Oncorhynchus nerka ) salmon were studied using the Pacific Ocean Shelf Tracking (POST) array. Smolts were acoustically tagged in 2004–2007, and their migration was recorded within the lower Fraser River and coastal southern British Columbia waters. Most smolts showed rapid directional movement (swimming speeds of ~15–30 km·day–1). Average exit time from the Fraser River was 4.0–5.6 days after release, and average residence time within the Strait of Georgia was 25.6–34.1 days. Most individuals migrated northward, generally close to the mainland coast. Survival rates, assessed using standard mark–recapture methods, were generally high during the downstream migration (50%–70%), except in 2005 when survival was <20%, possibly because of a late release. Marine survival rates were stable among years, between 10%–30% at a subarray sited 500 km away from the release site. Movement rates were similar to...
Variability in Migration Routes Influences Early Marine Survival of Juvenile Salmon Smolts
PloS one, 2015
Variability in animal migratory behavior is expected to influence fitness, but few empirical examples demonstrating this relationship exist. The initial marine phase in the migration of juvenile salmon smolts has been identified as a potentially critical life history stage to overall population productivity, yet how fine-scale migration routes may influence survival are unknown. Large-scale acoustic telemetry studies have estimated survival rates of outmigrant Pacific salmon smolts through the Strait of Georgia (SOG) along the British Columbian coastline to the Pacific Ocean, but these data have not been used to identify and characterize fine-scale movements. Data collected on over 850 sockeye salmon (Oncorhynchus nerka) and steelhead (Oncorhynchus mykiss) smolts detected at an array in the Strait of Georgia in 2004-2008 and 2010-2013 were analyzed to characterize migration routes and link movements to subsequent survival at an array 250 km further along the marine migration pathway...
Transactions of The American Fisheries Society, 2009
The migration of juvenile coho salmon Oncorhynchus kisutch out of the Strait of Georgia in 2006 was investigated by means of acoustic telemetry. During July and September, 173 juvenile coho salmon were caught in the strait with a purse seine, surgically implanted with acoustic tags, and released the same day. In 2006, approximately 19% of the fish tagged in July and 52% of those tagged in September left the Strait of Georgia. Most of these fish did so in October and November through Juan de Fuca Strait and not by a northward migration through Queen Charlotte Strait. This movement was several months later than that observed for coho salmon migrating out of Puget Sound. A small number of coho salmon that moved out of the Strait of Georgia migrated south to areas off the coast of Washington and Oregon. The documentation of a movement out of the Strait of Georgia late in the year was important, as it shows that population changes of the juvenile coho salmon that enter the strait during spring and summer are a consequence of ecosystem-related effects within the strait.