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Survival of migrating salmon smolts in large rivers with and without dams.

Welch DW, Rechisky EL, Melnychuk MC, Porter AD, Walters CJ, Clements S, Clemens BJ, McKinley RS, Schreck C - PLoS Biol. (2008)

Bottom Line: Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams.Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent.Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River.

View Article: PubMed Central - PubMed

Affiliation: Kintama Research, Nanaimo, British Columbia, Canada. david.welch@kintamaresearch.org

ABSTRACT
The mortality of salmon smolts during their migration out of freshwater and into the ocean has been difficult to measure. In the Columbia River, which has an extensive network of hydroelectric dams, the decline in abundance of adult salmon returning from the ocean since the late 1970s has been ascribed in large measure to the presence of the dams, although the completion of the hydropower system occurred at the same time as large-scale shifts in ocean climate, as measured by climate indices such as the Pacific Decadal Oscillation. We measured the survival of salmon smolts during their migration to sea using elements of the large-scale acoustic telemetry system, the Pacific Ocean Shelf Tracking (POST) array. Survival measurements using acoustic tags were comparable to those obtained independently using the Passive Integrated Transponder (PIT) tag system, which is operational at Columbia and Snake River dams. Because the technology underlying the POST array works in both freshwater and the ocean, it is therefore possible to extend the measurement of survival to large rivers lacking dams, such as the Fraser, and to also extend the measurement of survival to the lower Columbia River and estuary, where there are no dams. Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams. Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent. Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River.

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Geographic Location of Part of the POST Acoustic Array and Smolt Release SitesThe edge of the continental shelf (200-m depth contour) is shown, as well as acoustic listening lines located in the two rivers and in the Strait of Juan de Fuca (JdF) and northern Strait of Georgia (NSOG). Position of the 2002–2004 lower Columbia River array at Astoria is described in [30]. Release sites, marked with a filled square are as follows: 1: Deadman River; 2: Nicola River; 3: Spius Creek; 4: Coldwater River; 5: Coldwater River; 6: Bonneville Dam; 7: Snake River trap; and 8: Kooskia National Fish Hatchery. Receiver locations marked with open circles indicate 2004; filled triangles 2005; and filled circles 2006.
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pbio-0060265-g001: Geographic Location of Part of the POST Acoustic Array and Smolt Release SitesThe edge of the continental shelf (200-m depth contour) is shown, as well as acoustic listening lines located in the two rivers and in the Strait of Juan de Fuca (JdF) and northern Strait of Georgia (NSOG). Position of the 2002–2004 lower Columbia River array at Astoria is described in [30]. Release sites, marked with a filled square are as follows: 1: Deadman River; 2: Nicola River; 3: Spius Creek; 4: Coldwater River; 5: Coldwater River; 6: Bonneville Dam; 7: Snake River trap; and 8: Kooskia National Fish Hatchery. Receiver locations marked with open circles indicate 2004; filled triangles 2005; and filled circles 2006.

Mentions: The freshwater survival estimates for Thompson River smolts can be compared with two different measurements of survival of Snake River steelhead and Chinook smolts migrating down parts of the highly altered Snake-Columbia River system, which has eight major dams sited along the migration path (Figure 1). First, extensive measurements are available since 1997 of annual survival of PIT-tagged smolts migrating 516 km through the impounded section of the river from a release site in the Snake River at Lewiston, Idaho, through seven dams to the eighth and final dam at Bonneville on the Columbia River (river Km [RKm] 223) [21]. Second, survival in the unimpounded lower river and estuary from Bonneville Dam to Astoria Bridge (RKm 22) was measured in 2002–2004 using the same acoustic tag technology used in the Fraser River [29], providing an estimate of survival for the final, free-flowing section of the river, and which is consistent with radio tag estimates. Radio telemetry cannot be used to measure survival in the estuary, where saltwater is present. However, our survival estimates using radio telemetry for the region above the estuary, but below Bonneville dam, for the 3-y period 2002–2004 are similar to the survival estimates reported here that were obtained using acoustic telemetry [29,30].


Survival of migrating salmon smolts in large rivers with and without dams.

Welch DW, Rechisky EL, Melnychuk MC, Porter AD, Walters CJ, Clements S, Clemens BJ, McKinley RS, Schreck C - PLoS Biol. (2008)

Geographic Location of Part of the POST Acoustic Array and Smolt Release SitesThe edge of the continental shelf (200-m depth contour) is shown, as well as acoustic listening lines located in the two rivers and in the Strait of Juan de Fuca (JdF) and northern Strait of Georgia (NSOG). Position of the 2002–2004 lower Columbia River array at Astoria is described in [30]. Release sites, marked with a filled square are as follows: 1: Deadman River; 2: Nicola River; 3: Spius Creek; 4: Coldwater River; 5: Coldwater River; 6: Bonneville Dam; 7: Snake River trap; and 8: Kooskia National Fish Hatchery. Receiver locations marked with open circles indicate 2004; filled triangles 2005; and filled circles 2006.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2573937&req=5

pbio-0060265-g001: Geographic Location of Part of the POST Acoustic Array and Smolt Release SitesThe edge of the continental shelf (200-m depth contour) is shown, as well as acoustic listening lines located in the two rivers and in the Strait of Juan de Fuca (JdF) and northern Strait of Georgia (NSOG). Position of the 2002–2004 lower Columbia River array at Astoria is described in [30]. Release sites, marked with a filled square are as follows: 1: Deadman River; 2: Nicola River; 3: Spius Creek; 4: Coldwater River; 5: Coldwater River; 6: Bonneville Dam; 7: Snake River trap; and 8: Kooskia National Fish Hatchery. Receiver locations marked with open circles indicate 2004; filled triangles 2005; and filled circles 2006.
Mentions: The freshwater survival estimates for Thompson River smolts can be compared with two different measurements of survival of Snake River steelhead and Chinook smolts migrating down parts of the highly altered Snake-Columbia River system, which has eight major dams sited along the migration path (Figure 1). First, extensive measurements are available since 1997 of annual survival of PIT-tagged smolts migrating 516 km through the impounded section of the river from a release site in the Snake River at Lewiston, Idaho, through seven dams to the eighth and final dam at Bonneville on the Columbia River (river Km [RKm] 223) [21]. Second, survival in the unimpounded lower river and estuary from Bonneville Dam to Astoria Bridge (RKm 22) was measured in 2002–2004 using the same acoustic tag technology used in the Fraser River [29], providing an estimate of survival for the final, free-flowing section of the river, and which is consistent with radio tag estimates. Radio telemetry cannot be used to measure survival in the estuary, where saltwater is present. However, our survival estimates using radio telemetry for the region above the estuary, but below Bonneville dam, for the 3-y period 2002–2004 are similar to the survival estimates reported here that were obtained using acoustic telemetry [29,30].

Bottom Line: Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams.Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent.Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River.

View Article: PubMed Central - PubMed

Affiliation: Kintama Research, Nanaimo, British Columbia, Canada. david.welch@kintamaresearch.org

ABSTRACT
The mortality of salmon smolts during their migration out of freshwater and into the ocean has been difficult to measure. In the Columbia River, which has an extensive network of hydroelectric dams, the decline in abundance of adult salmon returning from the ocean since the late 1970s has been ascribed in large measure to the presence of the dams, although the completion of the hydropower system occurred at the same time as large-scale shifts in ocean climate, as measured by climate indices such as the Pacific Decadal Oscillation. We measured the survival of salmon smolts during their migration to sea using elements of the large-scale acoustic telemetry system, the Pacific Ocean Shelf Tracking (POST) array. Survival measurements using acoustic tags were comparable to those obtained independently using the Passive Integrated Transponder (PIT) tag system, which is operational at Columbia and Snake River dams. Because the technology underlying the POST array works in both freshwater and the ocean, it is therefore possible to extend the measurement of survival to large rivers lacking dams, such as the Fraser, and to also extend the measurement of survival to the lower Columbia River and estuary, where there are no dams. Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams. Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent. Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River.

Show MeSH
Related in: MedlinePlus