Quantifying component mortality estimates of out-migrating juvenile steelhead (<em>Oncorhynchus mykiss</em>)

Our study aimed to partition juvenile steelhead mortality among component sources using Predation Detection Acoustic Tags (PDATs). From March–May 2024, we tagged 300 juvenile steelhead (Oncorhynchus mykiss) (236 ± 30 mm fork length, range 144 – 302 mm) with PDATs and detected tagged fish using a passive receiver array in the San Joaquin River, CA, coupled with eight days of active tracking following each release. We categorized passive and active PDAT detections into three observations: (1) alive, (2) fish predation, and (3) unobserved. Additionally, we determined whether mortality was significantly related to biotic (e.g., fish size at release) and abiotic conditions (e.g., temperature, discharge).