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STOCKTON FWO: Service Participates in Collaborative South Delta Juvenile Salmon Survival Study
California-Nevada Offices , May 15, 2009
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Lori Smith of the USFWS implants an accoustic tag into a juvenile salmon. (photo: Patricia Brandes, USFWS)
Lori Smith of the USFWS implants an accoustic tag into a juvenile salmon. (photo: Patricia Brandes, USFWS) - Photo Credit: n/a
Jerrica Lewis of USFWS participates in tagging juvenile salmon as part of the Vernalis Adaptive Management Program. (photo: Patricia Brandes, USFWS)
Jerrica Lewis of USFWS participates in tagging juvenile salmon as part of the Vernalis Adaptive Management Program. (photo: Patricia Brandes, USFWS) - Photo Credit: n/a
Juvenile salmon with sutures from surgically implanting acoustic tags into their body cavities. (photo: Patricia Brandes, USFWS) 
Juvenile salmon with sutures from surgically implanting acoustic tags into their body cavities. (photo: Patricia Brandes, USFWS)  - Photo Credit: n/a
Jerrica Lewis (foreground) and Lori Smith help with the transport of acoustically-tagged juvenile salmon to the San Joaquin River as part of the Vernalis Adaptive Management Program. (photo: Mike Marshall, USFWS)
Jerrica Lewis (foreground) and Lori Smith help with the transport of acoustically-tagged juvenile salmon to the San Joaquin River as part of the Vernalis Adaptive Management Program. (photo: Mike Marshall, USFWS) - Photo Credit: n/a
USFWS Staff (Bill Powell and Jimmy Faulkner) move buckets of acoustically-tagged juvenile salmon into garbage cans (on the far side of the boat) for 24 hours of holding prior to release as part of the Vernalis Adaptive Management Program. (photo: Mike Marshall, USFWS)
USFWS Staff (Bill Powell and Jimmy Faulkner) move buckets of acoustically-tagged juvenile salmon into garbage cans (on the far side of the boat) for 24 hours of holding prior to release as part of the Vernalis Adaptive Management Program. (photo: Mike Marshall, USFWS) - Photo Credit: n/a
A striped bass with an external acoustic-tag being released into the river after tagging. (photo: Phil Voong, USFWS)
A striped bass with an external acoustic-tag being released into the river after tagging. (photo: Phil Voong, USFWS) - Photo Credit: n/a

by Patricia Brandes, Stockton FWO
The Service recently participated in a large-scale, collaborative project to estimate juvenile salmon survival through parts of the southern Sacramento-San Joaquin Delta of California as part of the Vernalis Adaptive Management Plan (VAMP).  Several agencies and contractors were involved in the study and included the Service’s Stockton Fish and Wildlife Office (STFWO) and California/Nevada Fish Health Center (CNFHC), the US Bureau of Reclamation (USBR), California Department’s of Water Resources (DWR) and Fish and Game, San Joaquin River Group Authority, University of Washington, Natural Resource Scientists Inc, FISHBIO, and Hanson Environmental. 

Participants in the project tagged and released 950 juvenile Chinook salmon with internal acoustic tags and deployed 15 acoustic receivers in the south Delta to estimate survival and migration distribution among channels. The acoustic tags emit sound pulses that can be detected by acoustic receivers as tagged individuals pass the receivers deployed at strategic locations through-out the south Delta.  Seven separate releases, of approximately 135 acoustic tagged salmon, were made over a 3 ½ week period starting in late April, 2009. Acoustic receivers will be in place until the end of May, 2009 to continue detecting acoustic tags.  In addition, a small number of striped bass and largemouth bass were tagged with external acoustic tags to better understand the movement of these predators in order to help distinguish between tags in live salmon versus those that have been eaten by predators. Mobile receivers mounted on boats were also used to identify areas where tags were found to be motionless indicating that the fish had died or the tag had been defecated by a predator and settled on the riverbed.     

The acoustic-tagged fish released for the VAMP were also used to support a study conducted by USBR to determine if a Non-Physical Barrier (NPB) or, “bubble curtain”, placed at the junction of the San Joaquin River and Old River would keep juvenile salmon from entering Old River.  Previous studies have suggested that mortality for juvenile salmon migrating through Old River is higher than for juvenile salmon migrating down the San Joaquin River and a NPB could help to direct fish into channels with a greater likelihood of survival.  The VAMP study also collaborated with DWR on an additional study to evaluate the impact of agricultural barriers on juvenile salmon and steelhead in the south Delta.  As part of DWR’s agricultural barrier study DWR deployed and maintained an additional 11 fixed-station, acoustic receivers in the south Delta.  These additional receiver stations will detect the fish tagged from the VAMP study and help DWR evaluate the impacts of the agricultural barriers on juvenile Chinook salmon migration.   

The STFWO led the coordination and planning phases of the VAMP study, assisted in the tagging, transport and release of the study fish, maintained and downloaded data from six receivers, and helped to tag predatory fish species.  Personnel from the CNFHC took samples from test fish held for 48 hours to detect pathological or physiological problems that could negatively affect fish survival. In addition, personnel from the CNFHC conducted bioassays to assess relative water quality effects near the Stockton Wastewater Treatment Plant. 

Preliminary results suggest that survival for the first 24 hours after tagging and transport to the release site was high but survival from the release site to the “bubble curtain” (approximately 15 miles), appeared lower than anticipated with estimates of survival ranging from 48 to 73%.  When the “bubble curtain” was on, it appeared to reduce the number of tagged salmon that entered Old River, although there was some evidence that tagged salmon were eaten by predators in the vicinity of the barrier.  Receivers placed in the San Joaquin River and Old River downstream of the “bubble curtain” will provide data for modeling and comparing survival in the two rivers.  Final results should be available by January of 2010.

Read the May 15, 2009 Stockton Record article on the study.


Contact Info: Patricia Brandes, 209-946-6400 X308, Pat_Brandes@fws.gov



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