Integrating mark-recapture, catch, and expert habitat assessments to quantify recent increases in humpback chub abundance over a 200 km long river segment of the Colorado River in western Grand Canyon
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Abstract
Humpback chub, Gila cypha, were historically distributed throughout large portions of the Colorado River basin and were federally listed in 1967. In the Grand Canyon segment of the Colorado River, located below Glen Canyon Dam, chub abundances continued to decline through the early 2000s. Recently, catch has increased substantially, especially in the western Grand Canyon. Here, we integrate mark-recapture and catch data of subadult and adult humpback chub, with expert assessments of habitat suitability and an underlying model of spatial autocorrelation, to estimate abundance in western Grand Canyon from 2010 to 2024, a time of rapid population increase and expansion. Our model suggests that adult abundance grew ∼160 fold during this 15-year period, with a median adult population abundance of 70 000 (40 000–200 000; 95% credible interval) in 2024. Our approach identifies years with high population growth and indicates that the spatial distribution has changed over time. We test the sensitivity of our results to movement into sampling reaches during sampling with baited hoop nets. Despite rapid population growth, the resilience of humpback chub in western Grand Canyon is unknown.
Suggested Citation
Dzul, M.C., Van Haverbeke, D.R., Young, K., Yackulic, C.B., Rinker, P., and Yard, M., 2026, Integrating mark-recapture, catch, and expert habitat assessments to quantify recent increases in humpback chub abundance over a 200 km long river segment of the Colorado River in western Grand Canyon: Canadian Journal of Fisheries and Aquatic Sciences, v. 83, p. 1-13, https://doi.org/10.1139/cjfas-2025-0169.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Integrating mark-recapture, catch, and expert habitat assessments to quantify recent increases in humpback chub abundance over a 200 km long river segment of the Colorado River in western Grand Canyon |
| Series title | Canadian Journal of Fisheries and Aquatic Sciences |
| DOI | 10.1139/cjfas-2025-0169 |
| Volume | 83 |
| Publication Date | May 13, 2026 |
| Year Published | 2026 |
| Language | English |
| Publisher | Canadian Science Publishing |
| Contributing office(s) | Southwest Biological Science Center |
| Description | 13 p. |
| First page | 1 |
| Last page | 13 |
| Country | United States |
| State | Arizona |
| Other Geospatial | Colorado River, Grand Canyon |