Health & Environmental Research Online (HERO)


Print Feedback Export to File
7583419 
Journal Article 
Fall Chinook Salmon (Oncorhynchus tshawytscha), Sand Roller (Percopsis transmontana), and Smallmouth Bass (Micropterus dolomieu) Interactions in a Snake River Reservoir: A Tale of Three Species 
Hemingway, RJ; Tiffan, KF; Erhardt, JM; Rhodes, TN; Bickford, BK 
2019 
1 
Northwestern Naturalist
ISSN: 1051-1733
EISSN: 1989-2004 
100 
1 
26-36 
English 
We studied some of the relationships between federally listed fall Chinook Salmon, Oncorhynchus tshawytscha, endemic Sand Roller, Percopsis transmontana, and non-native Smallmouth Bass, Micropterus dolomieu, in Lower Granite Reservoir on the Snake River. Because of its recent reappearance and population increase, the Sand Rollers could be filling the role of a “native invader” in the reservoir food web. We speculated that Sand Rollers could either negatively affect fall Chinook Salmon by potentially competing with them for resources in shoreline habitats or, alternatively, benefit the salmon by providing a buffer against Smallmouth Bass predation. Nighttime beach seining showed that habitat use by fall Chinook Salmon and Sand Rollers overlapped completely in spring when both species were present along shorelines. Diet data from stomach samples also showed high overlap, but data on stable isotopes of 13C and 15N suggested that each species could be obtaining much of their dietary energy from different reservoir locations. Although habitat and diet overlap are evidence of competition, diel and spatial partitioning of resource use between fall Chinook Salmon and Sand Rollers may act to reduce potential competition. Analyses of Smallmouth Bass diets showed that fall Chinook Salmon and Sand Rollers comprised the majority of prey fish consumed by bass. Across years, as Smallmouth Bass increased their consumption of Sand Rollers (range 0.219 to 0.392 fish smallmouth−1 day−1), they decreased their consumption of fall Chinook Salmon (range 0.114 to 0.050 fish smallmouth−1 day−1). The greatest effect Sand Rollers may have on fall Chinook Salmon in Lower Granite Reservoir is to serve as a buffer against Smallmouth Bass predation. 
article; abundance; Chinook Salmon; habitat; Lower Granite Reservoir; Sand Roller; Smallmouth Bass; Micropterus dolomieu; Oncorhynchus tshawytscha; Percopsis; food webs; forage fish; habitat preferences; habitats; nitrogen; population growth; predation; shorelines; stable isotopes; stomach; Snake River