Downstream rearing of juvenile Chinook salmon abundance, distribution and growth in the Upper Mainstem of the John Day River

Identification Information

Citation

Originator: Michael Scheu and Ian Tattam

Publish Date: 2018

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Ian Tattam

Job Position: Project Leader

Telephone: 541-962-3067

E-Mail Address: Ian.A.Tattam@odfw.oregon.gov

Description

Abstract: Juvenile spring Chinook (Oncorhynchus tshawytscha) emerge from the gravel in the late winter or early spring, and most follow a life history pattern known as Natal Reach Rearing (NRR) in which juvenile fish remain in the stream reaches where they were spawned until their second spring of life when they start migrating towards the ocean (Healey 1991). However, in Columbia River tributaries, some juveniles have been observed following a Downstream Rearing (DSR) life history, in which they start moving downstream during their first spring towards other nursery habitats or perhaps ocean rearing (Copeland & Venditti 2009; Schroeder et al. 2016). Rearing in different habitats during their first year gives fish with these two life histories access to diverse food resources and, it is hypothesized that, this leads to different survival and growth advantages for these two groups. Differences in growth are of interest in efforts to conserve this threatened species because size is positively correlated to survival for salmon across multiple stages of their life cycle (Groot & Margolis 1991; Healey 1991; Quinn & Peterson 1996; Roni et al. 2012) Chinook salmon in the upper John Day River, Oregon, exhibit both NRR and DSR life history patterns. Fish following the DSR life history pattern are larger than NRR fish late in the spring, possibly due to factors such as higher fish density, lower stream productivity, and colder water temperatures in their natal reach than in the downstream reaches. However, this size advantage may be lost due to adverse summer conditions. Hot summer days combined with the withdrawal of water for agriculture lead to stream water temperatures well above lethal thresholds for salmon in many downstream reaches. DSR fish have been observed in tributaries of the mainstem John Day River, however their growth and survival during summer is unknown.

Purpose: We set out with three main objectives, each with additional sub-objectives to address more specific questions. As research progressed other pertinent questions were considered. The main objectives, the sub-objectives, and the supplemental questions we developed during the course of our research (marked with a capital letter) are: Objective 1): Estimate the abundance of DSR Chinook in the John Day River and its Tributaries. 1.1 Does Bank of Release strategy affect recapture probability for juvenile Chinook salmon captured in and released upstream of a rotary screw trap? 1.1.A How does the recapture probability of fish released using our night release boxes compare to the capture rates of fish that have not encountered a screw trap? 1.2 What proportion of fish migrate back upstream of the John Day River rotary screw trap? 1.3 What are the end-of summer abundances and densities of DSR juvenile Chinook in tributaries of the John Day River? 1.3.A What is the abundance of sub yearling DSR Chinook salmon in the mainstem during the spring migration? Objective 2): Determine Spatial Distribution of juvenile DSR Chinook salmon. 2.1 How far downstream the mainstem are DSR juvenile Chinook salmon distributed during June and July? 2.2 What is the distribution of DSR juvenile Chinook salmon in the upper mainstem JDR and tributaries at the end of summer? Objective 3): Evaluate Physiological Indicators of juvenile DSR Chinook salmon. 3.1 Do indicators of smoltification differ between NRR and DSR life history juvenile Chinook salmon at the John Day River screw trap during May? 3.2 Do these indicators of smolting differ for DSR juvenile Chinook capture at the John Day River screw trap vary among weeks during May-July? 3.3 Does condition factor differ between DSR juvenile Chinook salmon captured at the John Day River rotary screw trap differ from those captured in tributaries during September? 3.3A How do DSR fish compare in size to their NRR cohort during the late spring trapping period at the John Day River screw trap? 3.3B Are there differences in the growth rates of DSR fish and their NRR cohort through the summer, and do their sizes equalize by the end of summer? 3.3C Are there differences in survival to the Columbia River between DSR fish and their NRR cohort in their second spring? Objective 4): Apply distribution maps and movement model to prioritization of restoration areas.

Time Period of Content: 2016-2017

Geographic Extent: John Day River Basin

Status: Final

Use Constraints:

Format: xlsx

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Is a physical copy maintained for reference at Headquarters? Unknown