The optimal management of salmonids in the Delta requires that the true fate of each tagged fish be known. Loss of tagged salmonids due to predation has been estimated to be as high as 65% (Vogel 2011). This data is ambiguous at best and survival estimates and behavioral results are biased. Hydroacoustic Technology Incorporated (HTI) has developed a prototype acoustic tag that has the ability to signal when a tagged fish has been eaten by a predatory fish. DWR and USBR staff were given 100 prototype predation tags for efficacy testing in live Chinook salmon.