Open-File Report 2010-1028
AbstractTo better understand and partition mortality among life stages of chum salmon (Oncorhynchus keta), we used inclined-plane traps to monitor the migration of juveniles in the Kwethluk River, Alaska in 2007 and 2008. The migration of juvenile chum salmon peaked in mid-May and catch rates were greatest when water levels were rising. Movement of chum salmon was diurnal with highest catch rates occurring during the hours of low light (that is, 22:00 to 10:00). Trap efficiency ranged from 0.37 to 4.04 percent (overall efficiency = 1.94 percent). Total abundance of juvenile chum salmon was estimated to be 2.0 million fish in 2007 and 2.9 million fish in 2008. On the basis of the estimate of chum salmon females passing the Kwethluk River weir and age-specific fecundity, we estimated the potential egg deposition (PED) upstream of the weir and trapping site. Egg-to-smolt survival, calculated by dividing the estimate of juvenile chum salmon emigrating past the weir site by the estimate of PED, was 4.6 percent in 2007 and 5.2 percent in 2008. In addition to chum salmon, Chinook salmon O. tshawytscha), coho salmon (O. kisutch), sockeye salmon (O. nerka), and pink salmon (O. gorbuscha), as well as ten other fish species, were captured in the traps. As with chum salmon, catch of these species increased during periods of increasing discharge and peaked during hours of low light. This study successfully determined the characteristics of juvenile salmon migrations and estimated egg-to-smolt survival for chum salmon. This is the first estimate of survival for any juvenile salmon in the Arctic-Yukon-Kuskokwim region of Alaska and demonstrates an approach that can help to partition mortality between freshwater and marine life stages, information critical to understanding the dynamics of salmon in this region. |
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Burrill, S.E., Zimmerman, C.E., Finn, J.E., and Gillikin, Daniel, 2010, Abundance, timing of migration, and egg-to-smolt survival of juvenile chum salmon, Kwethluk River, Alaska, 2007 and 2008: U.S. Geological Survey Open-File Report 2010–1028, 28 p.
Abstract
Introduction
Description of Study Area
Methods
Results
Discussion
Summary
Acknowledgments
References Cited
Appendix A. Mark-recapture data for fish traps used in the Kwethluk River, Alaska, 2007 and 2008
Appendix B. Daily catches of juvenile chum salmon along with readings for water stage, maximum water temperature, and minimum and maximum air temperature, Kwethluk River, 2007 and 2008