Movements and habitat selection of basking sharks, cetorhinus maximus gunnerus, in the western north Atlantic ocean
Bibliographic record
Abstract
The basking shark (Cetorhinus maximus, Gunnerus 1765) is the second largest extant fish species. It is a passive filter-feeder, well-documented to occur in productive temperate coastal seas with seasonally abundant zooplankton prey. Basking sharks have supported sporadic directed fisheries in the North Atlantic and elsewhere, but their populations were quickly depleted when exposed to significant fishing mortality. Given the basking shark's population status, and numerous gaps in our understanding of key biological parameters and ecological relationships, more research is necessary to help improve conservation and fisheries management. The goal of this study was to better quantify basking shark movements, habitat use and selection, and fisheries susceptibility using a combination of fishery-independent data sources. Satellite-linked Smart Position or Temperature Transmitting (SPOT) tags (N=10) and archived sightings data (N=144) were used to examine meso-scale movements and habitat selection with respect to numerous abiotic and biotic environmental factors during summer and fall months off the northeastern U.S. Pop-up Satellite Archival Tags (PSATs; N=57) were used to better quantify large-scale seasonal movements, fisheries susceptibility, and conservation status throughout the western North Atlantic. The results revealed that summer and fall presence and movements off the northeastern U.S. were associated with areas of high primary productivity, shallow bottom depths (<100 m), and high abundance of copepods including Centropages hamatus, Centropages typicus, and Calanus finmarchicus. There did not appear to be consistent selection for any particular zooplankton taxa, supporting the hypothesis that basking sharks are non-selective foragers in regions with high total zooplankton abundance. PSAT tracks revealed large-scale movements of basking sharks to the southeastern U.S., Sargasso Sea, Caribbean Sea, and as far as Brazil during winter and spring. These sharks passed through the territorial seas of at least 18 nations in which basking sharks have variable legal protection status. However, the tracked sharks cumulatively spent approximately 2/3 of their time adjacent to the U.S. and Canadian coasts where they are well-protected and fisheries bycatch is monitored. Collectively, the data presented in this dissertation will inform fisheries management and improve the ability to assess potential anthropogenic impacts on basking sharks in the western Atlantic. Furthermore, the results enhance our understanding of basking shark population structure and spatial ecology, setting the stage for additional investigations to further enhance their conservation.
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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 | 0.000 | 0.000 |
| 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) | 0.000 | 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".