March 1994

ks/0496 ; 03/07/96 12:00 AM ; 04/22/96 12:00 AM

Includes bibliographical references.

INTRODUCTION: Historically, chum were found in many Columbia River tributaries. Currently, there are a few tributaries that maintain low levels of chum production; however the only remaining viable natural spawning populations are found in the Grays River system and Hamilton and Hardy creeks in Washington. This report will focus on the Hardy Creek chum natural spawning population. Generally, Hardy Creek chum escapements have been measured by fish/mile and total population estimates. The "Status Report" lists escapement in fish/mile (WDF, 1993a). The "Salmon and Steelhead Stock Inventory" also lists escapement in fish/mile (WDF, 1993b). Washington Department of Fisheries (1951) estimated chum escapement at 4,000 fish for the minor tributaries of the Washougal River area including Hamilton and Hardy creeks. The numbers of chum spawning in Hardy Creek averaged about 160 fish annually from 1967-71 (Fiscus, 1973). The later estimate was incorporated into the "Fisheries Resources in Southwest Washington" Review Draft (WDF, 1973). In 1978, Washington Department of Fisheries (WDF) conducted a carcass tagging experiment to determine the Hardy Creek chum spawning population. A total of 26 chum carcasses were tagged and only 6 were recovered from Hardy Crek. The low number of recoveries failed to produce a population estimate fro Hardy Creek chum (Dammers, 1979). However, a chum carcass tagging experiment in Hamilton Creek was successful in 1978. Considering the close stream proximity and size in addition to the similar timing of chum between Hamilton and Hardy creeks, it was assumed that the same relationship existed between peak counts and total population estimates for both streams. Therefore, the 1.53 peak count expansion factor developed for the Hamilton Creek chum population in 1978 was applied to the Hardy Creek peak chum count. Based on the peak count expansion factor, an estimated 136 and 64 chum spawned in Hamilton and Hardy creeks in 1978, respectively (Dammers, 1979). Recent Hardy Creek chum population estimates have been developed by the Hamilton Creek peak count expansion factor. These population estimates have been published in several reports including "The Stock Assessment Report" (Howell et al. 1984) and "Columbia River Subbasin Plan". (WDF, 1990). Chum escapement levels in Hamilton and Hardy creeks have come full circle. The 1978 carcass tagging experiment was successful in Hamilton Creek but failed in Hardy Creek because of low numbers of fish. In 1993, Hamilton Creek chum stock status was classified as depressed based on a long-term negative escapement trend. Hardy Creek chum stock status was classified as healthy (WDF, 1993b). Because of the apparent shift in spawning escapement trends and the importance of Hardy Creek as a major Columbia River chum producer, a carcass tagging study was conducted in Hardy Creek in 1993. The carcass tagging study was an attempt to improve Hardy Creek chum population estimates. The peak count expansion factor developed from the 1993 carcass tagging study (if applicable) could be applied to the historic peak fish counts. Spawning ground counts have been conducted since 1957 on Hardy Creek. Chum index counts are likely to be conducted under less than optimum water conditions. The Grays River chum carcass tagging studies were affected by water visibility conditions for determining the actual peak counts necessary for generating natural spawn population estimates. Hardy Creek water conditions were also examined to determine whether counting efficiency was affected. By creating individual peak count and visibility expansion factors from the 1993 carcass tagging study, it will be possible to improve Hardy Creek chum population estimates, both past and present. By determining the population estimates for this stream, a single reference source could be used for future reports. Age composition data has been gathered for many years from Hardy Creek. By combining the population estimates with the age composition, a cohort database can be created. This cohort database, which includes return and brood year tables, could eventually be used to predict future runs. Hardy Creek is the last remaining Washington Columbia River chum current index area to have a be carcass tagging study done to generate natural spawn population estimates. In addition to the Hamilton Creek chum carcass tagging study in 1978, similar studies were conducted in the Grays River system in 1978 and 1991. Details of the 1993 Hardy Creek carcass tagging study and peak count and visibility expansion factors for that stream are provided below.