Large wood aids spawning Chinook salmon (Oncorhynchus tshawytscha) in marginal habitat on a regulated river in California

• Published in: River research and applications Vol. 27; no. 5; pp. 550 - 565
• Main Authors: Senter, A.E, Pasternack, G.B
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.06.2011; Wiley
• Subjects: Aids; Animal and plant ecology; Animal, plant and microbial ecology; Applied sciences; Bends; Biological and medical sciences; Buildings. Public works; Channels; Chinook salmon; ecohydraulics; Exact sciences and technology; fluvial geomorphology; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; gravel rivers; Habitats; Hydraulic constructions; islands; large wood; managers; Mediterranean climate; nests; Oncorhynchus tshawytscha; Rehabilitation; River flow control. Flood control; river rehabilitation; Rivers; Salmon; spawning; Synecology; Wood; California; United States; North America; America; Oncorhynchus tshawytscha; gravel rivers; Wood; Spawning; fluvial geomorphology; Rivers; ecohydraulics; Vertebrata; Chinook salmon; Pisces; Riverflow control; large wood; river rehabilitation; Stream; Habitat; Gravel; Rehabilitation; fluvial features
• ISSN: 1535-1459; 1535-1467; 1535-1467
• DOI: 10.1002/rra.1388

To determine whether large wood (LW, ≥1-m length, ≥10-cm diameter) plays a role in Chinook salmon (Oncorhynchus tshawytscha) redd (i.e. egg nest) placements in a regulated, Mediterranean-climate, medium-sized river (where channel width is less than the upper quartile of length of potential instream wood pieces), characteristics of 527 large wood pieces, locations of 650 redds, and mesohabitat delineations (riffle, run, glide, pool) were collected during a spawning season along a 7.7 km reach directly below Camanche Dam on the Mokelumne River, CA. LW was regularly distributed across the study reach an average 70 LW pieces km-¹. Some LW clustering was evident at islands and meander bends. Spawners built 85% of redds within one average channel width (31 m) of LW. Spawners utilized LW within a 10 m radius 36% of the time in the upper 3 km rehabilitated reach, and 44% of the time in the lower 4.7 km marginal habitat reach. A greater percentage of LW was utilized in riffles in the upper 3 km reach where 90% of redds were built, while a larger percentage of spawners used LW in riffles in the lower 4.7 km reach. LW-redd interactions occurred at greater rates than by random chance alone in the lower 4.7 km reach, which implies that LW aids spawning in marginal habitats. River managers and salmonid spawning habitat rehabilitation (SHR) projects should take LW additions into consideration as an important component of river rehabilitation. Copyright © 2010 John Wiley & Sons, Ltd.