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LODI FWO: South Delta survival studies in 2016
California-Nevada Offices , December 9, 2016
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Tagging crew Rachel August (CDWR), Jerrica Lewis, and Cheyenne Hefley (USFWS) surgically implant acoustic tags into Chinook Salmon at the Merced River Hatchery.
Tagging crew Rachel August (CDWR), Jerrica Lewis, and Cheyenne Hefley (USFWS) surgically implant acoustic tags into Chinook Salmon at the Merced River Hatchery. - Photo Credit: USFWS
Louanne McMartin (USFWS, right) uses hydrophones and receivers to verify acoustic tag codes in tagged Chinook Salmon, while Raymond Bark (USBR) and Duncan Fry (USFWS) transfer verified salmon into transport buckets. The buckets were loaded onto the truck and taken to the release site.
Louanne McMartin (USFWS, right) uses hydrophones and receivers to verify acoustic tag codes in tagged Chinook Salmon, while Raymond Bark (USBR) and Duncan Fry (USFWS) transfer verified salmon into transport buckets. The buckets were loaded onto the truck and taken to the release site. - Photo Credit: USFWS
Carlie Jackson and Graham Mytton (USFWS) transport buckets holding acoustically tagged Chinook Salmon to holding cans at the Durham Ferry release site on the San Joaquin River.
Carlie Jackson and Graham Mytton (USFWS) transport buckets holding acoustically tagged Chinook Salmon to holding cans at the Durham Ferry release site on the San Joaquin River. - Photo Credit: USFWS

By Pat Brandes

 

During the spring of 2016, the Lodi Fish and Wildlife Office participated in two salmonid survival studies. The studies estimated juvenile Chinook salmon and steelhead survival through the lower San Joaquin River and Delta. The studies will identify route distribution, route specific survival and total through-Delta survival through the use of acoustic telemetry. The objectives of the studies are to help identify the causes of mortality in the Delta due to flows, exports and other effects on smolts out-migrating from the San Joaquin Basin. The 2016 juvenile steelhead study is the sixth year of a six year study funded by U.S. Bureau of Reclamation as a reasonable and prudent alternative (Action IV.2.2, NMFS, 2009, page 645), for the National Marine Fisheries Service’s, Biological Opinion and Conference Opinion on the Long-term Operations of the Central Valley Project and State Water Project. The juvenile Chinook salmon study was funded by Central Valley Project Improvement Act and others to assess survival through the lower San Joaquin River and Delta with a head of Old River barrier installed.

Three groups of juvenile steelhead from the Mokelumne River Hatchery were released between mid-February and late April. Each steelhead group consisted of 480 tagged fish, tagged over a 3 day period. The juvenile Chinook salmon were from the Merced River Hatchery and were released during April. Each salmon group consisted of 648 tagged salmon, tagged over a 4 day period, for two consecutive weeks. For all of the steelhead and half of the salmon, the tagged fish were transported to the release site (Durham Ferry) and held in containers for approximately 24 hours prior to release to allow for acclimation. Fish were then released every 4 to 6 hours over a 24-hour period, after being held for 24 hours. The other half of the tagged salmon were held for 24 hours near Stockton and released in the mainstem San Joaquin River on the slack tide before the ebb or during the ebb tide. The Stockton release was made in 2016 to provide better estimates of survival downstream of Stockton. Previously, survival has been so poor through the Delta that estimates of survival in downstream reaches were uncertain due to low numbers arriving there. Having a supplemental release at Stockton was a way to increase precision of the downstream survival estimates.

The Salmonid Survival Studies Program was responsible for the tagging and release components of the studies but these projects had labor contributions from other programs within the Lodi Fish and Wildlife Service (Delta Juvenile Fish Monitoring Program and Aquatic Invasive Species Program) as well as the U.S. Bureau of Reclamation and California Department of Water Resources. Administration staff at the Lodi office also contributed to the project by ordering services and purchasing supplies. The Service’s CA/NV Fish Health Center conducted the fish health analyses on a subset of the fish after they had been held at the release sites for 48 hours. The two individuals from the U.S. Bureau of Reclamation (USBR) (one from the Sacramento Bay-Delta office and one from the Denver Technical Service Center) contributed to the project by driving fish transport tanks. One staff member from the California Department of Water Resources was a surgeon and contributed to the tagging.

The California Department of Fish and Wildlife (CDFW), USBR, and the United States Geological Survey also supported the project by providing fish and tagging space and by deploying and maintaining the wide-spread receiver array in the Delta. The Chinook salmon were provided by the CDFW’s Merced River Fish Hatchery and the steelhead were provided by the Mokelumne River Fish Hatchery, an East Bay Municipal District (EBMUD) hatchery operated by the California Department of Fish and Wildlife. Lastly, the receiver array was funded by the USBR as part of the 6 year steelhead study, and was deployed and maintained by the U.S. Geological Survey.

It will be a couple of months before all the data is downloaded from the receivers and several more months before the data is completely analyzed, but the tagging and the release components of the projects have been completed for this year. Several challenges were encountered and overcome this year, with the greatest being the small fish at Merced River Fish Hatchery for the first week of tagging, such that we had to increase the tag to body weight ratio from 5% to 7%. It was through the hard work, dedication and cooperation of our diverse team and support from our partners that helped us succeed. This was also the first year that Denise Barnard led the tagging crews and she did an awesome job.


Contact Info: Yvette Sky, (209) 334-2968 x301, yvette_sky@fws.gov
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