Oncorhynchus Bayesian ANalysis (OBAN)
A Statistical Model of Central Valley Chinook Incorporating Uncertainty
OBAN is a statistical modeling approach that incorporates mortality in all phases of salmon life history, and includes the effects of uncertainty in assessing population status.
The objectives of the project are to:
- estimate population vital rates by fitting predictions of the population dynamics model to observed indices of abundance;
- evaluate covariates that may explain dynamic vital rates (e.g., thermal mortality affects alevin survival rates in spawning reaches); and
- explicitly incorporate uncertainty in the estimation procedure by fitting in a Bayesian framework.
CALFED Objectives
OBAN is funded by CALFED and was developed by a collaboration of R2 Resource Consultants, Inc., University of Washington, and NOAA Fisheries to meet the following CALFED objectives:
- Construct a life cycle model of several key species, and of necessity it must account for all stresses on those species, including environmental influences and the effects of diversions
- Provide prediction and strategic assessments for water management
- Improve effectiveness of monitoring by reducing unexplained variability in populations through direct accounting for the effects of ocean conditions and fisheries on survival of salmonids
OBAN Models
Two OBAN models are currently in the process of being constructed: one for winter-run and one for spring-run Chinook on the Sacramento River. The winter OBAN model is a user-friendly framework for exploring factors hypothesized to affect winter run population dynamics. For example, much of the variability in winter run abundance can be explained by temperature during egg incubation and indices of harvest. Other factors that
could be addressed include: access to rearing in Yolo Bypass, exports during the outmigration period, striped bass adult abundance indices, and near-shore ocean conditions.
Available downloads from this site are the description of the winter-run model, and a simplified working version of the OBAN model, with a user guide included.
Contact Information
The process of model development and refinement is an iterative one; therefore, comments and criticisms of the models and model descriptions are strongly encouraged. Please email comments/criticisms to Dr. Noble Hendrix (nhendrix@r2usa.com).
