Long‐Term Population Dynamics of the Endangered Snake River Sockeye Salmon: Evidence of Past Influences on Stock Decline and Impediments to Recovery
Bibliographic record
Abstract
Abstract Declines in populations of Pacific salmon Oncorhynchus spp. have been most pronounced in the southern extent of their range, and numerous anthropogenic stressors and natural drivers have been identified as potential causes. Using a paleolimnological approach, we have reconstructed the natural variability in the population dynamics of endangered Snake River sockeye salmon O. nerka over approximately the past 1,370 years. The rearing habitat ecology of their main production system, Redfish Lake, Idaho was also assessed over the past 500 years. Siliceous algal remains (diatoms and chrysophytes), stable nitrogen isotope δ15N, cladoceran zooplankton subfossils, and other proxy indicators archived in dated lake sediment cores were employed in this analysis. The inferred natural salmon production was much higher than that recorded in fisheries escapement data. Unprecedented declines in Snake River sockeye salmon production and changes in rearing system ecology were inferred over the past 150 years. The early, negative influences of the Columbia River commercial salmon harvest (in the 1860s) and sustained interruption of migration access (1910‐1934) from hydroelectric damming were evident. Enhanced zooplanktivory, associated with nonnative stocking and possible expansion of kokanee (lacustrine sockeye salmon) beginning in the 1920s and 1930s, appear to have altered the forage base for juvenile sockeye salmon, probably contributing to further declines. Lake nutrient enrichment since the 1950s was inferred, which changed nursery lake nutrient and trophic dynamics. This study highlights both site‐specific and regional influences on declines in past Snake River sockeye salmon population abundance and changes in rearing system ecology for these fish over the past 150 years. Such a long‐term ecological perspective is important to the continued conservation and management of this endangered species and has broader applications for other sockeye salmon runs at risk throughout their range.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".