The Pacific Salmon Commission has designated the Salmon River hatchery stock of fall Chinook as an Exploitation Rate Indicator Stock (ERIS) for all 16 naturally produced stocks of fall Chinook on Oregon's north coast. The Pacific Salmon Treaty (PST) specifies the necessity of these stocks to model the effects of mixed stock fisheries on wild Chinook salmon. The ocean migration patterns and catch rates of this stock are thought to closely resemble Oregon's north migrating Chinook from coastal basins ranging from the Necanicum River in the north to the Siuslaw River in the south. A relatively long and continuous history of mark and recapture experiments with corresponding extensive spawning ground surveys and harvest estimates from a fresh water creel, serves as the foundation for a predictive model of spawner abundance. Peak counts from two spawning ground surveys were identified as an index that strongly correlates with relatively precise abundance estimates derived from a Peterson two event mark-recapture model. Index surveys are less labor intensive than previous mark-recapture activities, and evidence suggests they are an efficient and cost effective method to estimate spawner abundance.

The John Day River basin supports one of the healthiest naturally-produced populations of spring chinook in the mid-Columbia River basin. The study of life history and natural escapement conducted from 1978 to 1985 (Lindsay et al. 1986) provided valuable information on production and productivity of the John Day River spring chinook. With the exception of two years since completion of the study in 1985 (1989 and 1995), spring chinook spawning surveys were conducted in index areas only and have not provided adequate information to assess age composition, progeny-to-parent production values, and estimate natural spawning escapement. The PATH project (Marmorek and Peters 1996) has identified the John Day basin spring chinook as an index population for assessing the effects of alternative future management actions on salmon stocks in the Columbia Basin. To meet the data needs as an index stock, sufficient annual estimates of spawner escapement, age composition, and smolt-to-adult survival are essential. There is need to determine the annual spawner escapement and age composition for the John Day basin spring chinook to provide us the ability to estimate progeny-to-parent production for each brood year. This need can be met by expanding the annual chinook spawning surveys, estimating the annual escapement, and determining age composition by scale pattern analyses. This project provides information as directed under two measures of the Columbia Basin Fish and Wildlife Program (NPPC 1994). Measure 4.3C specifies that the key indicator populations should be monitored to provide detailed stock status information. In addition, measure 7.1C identifies the need for collection of population status, life history, and other data on wild and naturally spawning populations. This project was developed in direct response to recommendations and needs of the PATH project, the Fish and Wildlife Program, and the Columbia Basin Fish and Wildlife Authority Multi-Year Implementation Plan.