Key life stages and habitats included in the spring-run Chinook life cycle model. Courtesy of Flora Cordoleani
Filling significant recently identified gaps in monitoring spring-run Chinook is critical to protecting these threatened Central Valley salmon.
"There's no way we can manage them for recovery if we don't understand the biological processes that govern their dynamics through time and space," says UC Santa Cruz/NOAA salmon expert Flora Cordoleani, lead author of a study reported
in the December 2020 issue of San Francisco Estuary and Watershed Science. Cordoleani and colleagues identified the monitoring gaps while building a model of the spring-run Chinook life cycle. The model accounts for three self-sustaining populations of these at-risk fish, assessing survival of key life stages (eggs, fry, smolts and adults) as well as in key habitats (natal creeks, the Sacramento River, floodplains in the Sutter and Yolo bypasses, the Sacramento-San Joaquin Delta
, and San Francisco Bay). "It's a complex model, and we needed data to fine-tune and test it," Cordoleani explains. "But there wasn't much." Major monitoring gaps include how many juveniles each population produces, and how many survive in the ocean. "Spring-run Chinook haven't gotten as much attention because they are less endangered than winter-run Chinook," she continues. That is beginning to change: The California Department of Water Resources is now working to estimate how many spring-run juveniles make it to the Delta. Identifying trouble spots for young salmon is vital to helping them. "Then you know where to focus management so the salmon can recover," Cordoleani says."We're trying to fill the gap between the data we have and what we really need—we can then go to stakeholders and say, 'This is where we should put our efforts to protect and conserve spring-run Chinook.’"