Long-term reconstruction of deep-water oxygen conditions in Osoyoos Lake (British Columbia, Canada): implications for Okanagan River sockeye salmon

Simmatis, Brigitte; Jeziorski, Adam; Zemanek, Andrea; Selbie, Daniel T.; Hyatt, Kim D.; Fryer, Jeffrey K.; Cumming, Brian F.; Smol, John P.

doi:10.1080/10402381.2018.1488779

Cited by 2 publications

(1 citation statement)

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“…Most of the 20th-century spawning and rearing habitat of Okanagan Sockeye in the Okanagan River Basin [57] was, therefore, restricted to approximately 20 km of the Okanagan River near Oliver, British Columbia, and Osoyoos Lake [33]. Most juvenile Okanagan Sockeye rear in portions of Osoyoos Lake, where increasing water temperatures of the epilimnion and decreasing hypolimnetic oxygen concentrations resulting from anthropogenic eutrophication greatly reduce suitable nursery habitat for juveniles during late summer each year [61]. This situation emphasizes the importance of interventions to increase the diversity and spatial structure for Okanagan Sockeye.…”

Section: Introductionmentioning

confidence: 99%

Migration and survival of Okanagan River Sockeye Salmon Oncorhynchus nerka, 2012–2019

Murauskas¹,

Hyatt

Fryer

et al. 2021

Anim Biotelemetry

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Background Okanagan River Sockeye Salmon Oncorhynchus nerka (Okanagan Sockeye) are one of two remaining self-sustaining Sockeye Salmon populations in the Columbia River Basin. We used detection histories of smolts implanted with passive integrated transponder (PIT) tags between 2012 and 2019 to estimate survival and behavioral metrics during reintroduction efforts and changing environmental conditions over the monitoring period. Results Smolts migrating to McNary Dam, whose route includes 130 km of the Okanagan River and 388 km of the Columbia River, generally had high survival (mean of 87.0% per 100 km) and fast migration speeds (up to 50 km/day) relative to other salmonids in the region. Smolt-to-adult returns (SARs) ranged from 0.4 to 6.1% and were greater for fish originating from Skaha Lake compared to cohorts tagged in Osoyoos Lake. Most adults returned after 2 years in the ocean (69%), followed by jacks (27%), and adults that spent 3 years at sea (4%), though Skaha Lake adults had a significantly younger age structure than cohorts from Osoyoos Lake. Survival of adults from Bonneville Dam (rkm 235) upstream to Wells Dam (rkm 830) was generally high (80–92%), and migration speed decreased in upstream reaches. Survival from Wells Dam to the Okanagan River was only estimable in 2018, where 64% of adults survived to the spawning grounds. The upstream migration of adult Okanagan Sockeye was significantly compromised during the drought of 2015 when less than 5% of Okanagan Sockeye that returned to the Columbia River reached spawning grounds. Conclusions Our results indicate that Okanagan Sockeye have exceptional survival and migratory ability relative to other salmonids, though poor ocean conditions combined with warming water temperatures in freshwater habitats in recent years have the potential to devastate the population. The success of reintroduction efforts to increase spatial structure and diversity of Okanagan Sockeye is, therefore, critical to maintaining the population in years to come.

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Section: Introductionmentioning

confidence: 99%