Summer Diet of Humpback Whales in the Northern Strait of Georgia, British Columbia (Canada), Revealed by Stable Isotope Analysis
Bibliographic record
Abstract
ABSTRACT North Pacific humpback whales ( Megaptera novaeangliae ) have recovered rapidly following their depletion by commercial whaling. Diet studies are necessary to assess food web implications of their recovery. This study investigates the diet composition of humpback whales foraging in the northern Strait of Georgia, British Columbia, Canada, an area experiencing a recent return of humpback whales. Humpback whale skin samples ( n = 108), juvenile herring ( n = 202), adult herring ( n = 23), euphausiids ( n = 63), and amphipods ( n = 6) were collected in the summer months of 2022 and 2023 and analyzed for carbon (δ 13 C) and nitrogen (δ 15 N) stable isotopes. Applying these isotope data, the Bayesian mixing model MixSIAR was used to estimate the contribution of each prey type to humpback whale diet. We found that, during the summer months, humpback whales primarily consumed euphausiids (85.3%, range: 76.4%–94.0%) and juvenile herring (10.2%, range: 0.8%–21.0%), with minimal contributions from adult herring and amphipods. Diet composition was consistent across months and years. These findings provide critical insights into humpback whale foraging ecology, informing conservation efforts for both predator and prey species in the region.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.004 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 teacher head, 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".