Figure 8. Generalized migration and breeding chronology for the Willow Flycatcher in the Southwest. Extreme or record dates may occur slightly earlier or later than indicated.

There are four distinct runs of Chinook Salmon (Oncorhynchus tshawytscha) in the Central Valley, named after their primary adult return times: fall, late-fall, winter, and spring run. Estimating the run-specific composition of juveniles entering and leaving the Sacramento–San Joaquin Delta is crucial for assessing population status and processes that affect juvenile survival through the Delta. Historically, the run of juvenile Chinook Salmon captured in the field has been determined using a length-at-date criteria (LDC); however, LDC run assignments may be inaccurate if there is high overlap in the run-specific timing and size of juveniles entering and leaving the Delta. In this study, we use genetic run assignments to assess the accuracy of LDC at two trawl locations in the Sacramento River (Delta entry) and at Chipps Island (Delta exit). Fin tissues were collected from approximately 7,500 juvenile Chinook Salmon captured in trawl samples between 2007 and 2011. Tissues were analyzed using 21 microsatellites to determine genetic run assignments for individuals, which we compared with LDC run assignments. Across years, there was extensive overlap among the distributions of run-specific fork lengths of genetically identified juveniles, indicating that run compositions based on LDC assignments would tend to underestimate fall-run and especially late-fall-run compositions at both trawl locations, and greatly overestimate spring-run compositions (both locations) and winter-run compositions (Chipps Island). We therefore strongly support ongoing efforts to include tissue sampling and genetic run identification of juvenile Chinook Salmon at key monitoring locations in the Sacramento–San Joaquin River system.

This report summarizes activities in 1983, the second of a five year study to determine the extent of predation by resident populations of native and introduced fishes on juvenile salmonids in John Day Reservoir. As in 1982, catches of northern squawfish (Ptychocheilus oregonensis) were highest in areas adjacent to dams: percent by weight of juvenile salmonids in the diet was up to 89.7% higher in these areas. Catches of walleyes (Stisostedion vitreum vitreum) were greatest outside restricted zones (700-900 m above and below the dams) in spring of both 1982 and 1983. P boercent by weight of juvenile salmonids in walleyes collected in 1983 was generally higher at McNary tailrace and lower at Irrigon and John Day tailrace than in 1982. Smallmouth bass (Micropterus dolomieui) was the most common species collected and contained few salmonids in 1983. Results of the diet analysis for channel catfish (Ictalurus punctatus) varied substantially between 1982 and 1983 as a result of eliminating the John Day River sampling transect and increasing sampling effort at McNary tailrace, Irrigon, and John Day tailrace. The beach seine and boat electroshocker were effective gears for evaluating prey abundance.Data obtained to estimate relationships between fork length of juvenile chinook salmon (Oncorhynchus tshawytscha) and other body or bone measurements indicated that body length predicted fork length best, followed by cleithrum, dentary, and oopercle measurements. Digestion over time was estimated for 162 northern squawfish fed juvenile salmonids at temperatures ranging from

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