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US Fish & Wildlife Service FieldNotes

STOCKTON FWO: Study looks at restoration of Liberty Island

Region 8, September 16, 2011
Stockton Fish and Wildlife Office and Washington State University staff and students setting a Fyke net at Liberty Island.
Stockton Fish and Wildlife Office and Washington State University staff and students setting a Fyke net at Liberty Island. - Photo Credit: n/a
Fall out traps set at Liberty Island to collect insects.
Fall out traps set at Liberty Island to collect insects. - Photo Credit: n/a

By Lori Smith, Stockton FWO

In 2009, the Stockton Fish and Wildlife Office assisted in developing a study known as Breach III, to assess the effects of restoration on aquatic biota living in the tidally-influenced freshwater wetlands at Liberty Island and Little Holland Tract in Yolo County, Calif. The goals of the project were to provide a better understanding of how restoration activities influence local flooding and levee erosion and how abiotic and biotic factors control aquatic vegetation, fish, and wildlife.

This year the Service 's Delta Juvenile Fish Monitoring Program (DJFMP) collaborated with the University of Washington and Washington State University to simultaneously look at the macro-invertebrate and fish response tasks of the study at Liberty Island during one of three hydrologic periods. The Service assisted the universities by providing two boats and scientists to facilitate sampling.

The fish sampling, led by the WSU, was designed to evaluate the use of a restoring wetland by specific life stages of delta smelt, longfin smelt, Chinook salmon, striped bass, threadfin shad, and Sacramento splittail. Adult and juvenile fishes were sampled using gill and fyke nets at six locations to monitor both the abundance and diet of fishes. In addition, the DJFMP sampled larval fishes using trawls to monitor larval fish abundance throughout Liberty Island. The macro-invertebrate sampling, led by the UW, was designed to identify and monitor communities associated with the spatial and temporal development of the restoring wetland with emphasis on prey taxa of priority fishes. The UW took benthic core samples, conducted zooplankton trawls, and deployed insect fall-out traps to monitor the abundance of macro-invertebrates under the substrate, within the water column, and on the water’s surface, respectively.

The results from the fish and macro-invertebrate monitoring will be used in a model for predicting the ecological responses to change in habitat structure as a restoring system passes through the vegetation re-colonization threshold and continues to expand into a predominantly vegetated wetland landscape. Upon completion of the Breach III study in June 2013 the results from the entire study will be published in a final report to the California Department of Fish and Game as per the CALFed funded Breach III agreement.

Contact Info: Joseph Kirsch, 209-334-2968 ext. 309, joseph_kirsch@fws.gov