US Fish and Wildlife Services Research Project

Estimating survival and migration of coded wire and ultrasonic tagged late-fall Chinook smolts during their passage through Delta of the Sacramento San Joaquin watershed

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In addition, CWT groups were also released at Ryde and Benicia in both December 2006 and January 2007, but they were released at one time and were not held or released over the tidal cycle. Receivers were placed throughout the Delta and salmon with ultrasonic tags were detected as they migrated through the Delta. The data will show how many juvenile salmon migrate into the various channels in the Delta when the Delta Cross Channel gates are open and closed. CWTs will be recovered using a midwater trawl at Chipps Island. Survival will be estimated to Chipps Island using both the ultrasonic tagged and CWT salmon released at Sacramento. The CWT releases at Ryde and Benicia function as controls and represent juvenile salmon not exposed to the interior Delta, Steamboat and Sutter Sloughs and the Delta, respectively. Recoveries of the CWT groups will also be made in the ocean fishery as adults in future years. The relative recovery rates in the ocean fishery of the Sacramento group relative to the Ryde and Benicia groups will provide additional independent estimates of survival through and in the Delta.

Ultrasonic tags were surgically implanted and were Vemco V7-1L (17.5 mm and 1.4g)for the December release and Vemco V7-2L (18.5 mm and 1.6g) tags in January. Only fish greater than 140 millimeters were selected for tagging. Tags were inserted into the peritoneal cavity and held for 5 days after tagging prior to transportation to the release site. Ultrasonically tagged fish were trucked separately from the coded wire tagged fish.

A statistical model for the ultrasonic telemetry data will be developed to estimate both population distribution and survival rates through the Delta. This model will be based on classic release-recapture models, but will be extended to estimate (1) probabilities of fish using specific migration routes, (2) probability of surviving through each route, and (3) detection probabilities of each receiver. These parameters will describe how fish distribute through the Delta and survive in different areas of the Delta. We will also examine how factors such as tides, exports, and operation of the Delta Cross Channel affect distribution and survival of juvenile Chinook salmon.

We have received detection data from most of the monitors deployed in the Delta. We will be asking others working in the Delta for data from the CVP and SWP facilities where similar VEMCO receivers were deployed (Kevin Clark, DWR). Trawling at Chipps Island has been completed and survival estimates from coded wire tag recoveries have been estimated. Sonic tag data is being compiled and analyzed. Results will be shared in the tagging symposium of the national AFS meeting in San Francisco in September of 2007.