Salmon stocks in California collapsed in 2007, likely because of high mortality rates of juveniles entering the sea in 2005. In this project, fish ear bones (otoliths) are being analyzed to estimate the sizes and growth rates of Chinook salmon. In particular, the otoliths of salmon caught in San Francisco Bay are being compared with otoliths from salmon caught six months later in coastal waters. Among this sample, larger juveniles entering the sea were more likely to survive another six months than the smaller, slower growing ones. This size advantage was most pronounced during periods of low ocean productivity, when food was in short supply. In the last year of the project, the fellow will investigate whether survival rates of hatchery and wild juveniles are also markedly different when marine food resources are scarce. Results will, among other things, help identify the rivers or hatcheries that produce salmon most likely to survive during poor oceanic conditions.