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Detection of Threatened Delta Smelt in the Gut Contents of the Invasive Mississippi Silverside in the San Francisco Estuary Using TaqMan Assays
Author(s) -
Baerwald Melinda R.,
Schreier Brian M.,
Schumer Gregg,
May Bernie
Publication year - 2012
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1080/00028487.2012.717521
Subject(s) - smelt , estuary , biology , delta , fishery , predation , threatened species , mississippi delta , zoology , ecology , fish <actinopterygii> , habitat , environmental science , engineering , aerospace engineering , water resource management
In the San Francisco Estuary, predation of the threatened delta smelt Hypomesus transpacificus by the invasive Mississippi silverside Menidia audens has been hypothesized but unconfirmed in the wild due to difficulties in reliably identifying egg or larval fish remains in gut contents. This study describes the use of TaqMan assays to examine the gut contents of wild Mississippi silversides for the presence of delta smelt DNA. The species‐specific delta smelt assay was found to be highly sensitive and, in feeding trial experiments, capable of detecting delta smelt DNA in Mississippi silverside gut contents up to 36 h postingestion for some individuals. A substantial percentage (41%) of the 37 Mississippi silversides caught in the wild with midchannel trawling were positive for delta smelt DNA in their gut contents. Conversely, none of the 614 Mississippi silversides caught in the wild in nearshore beach seining contained delta smelt DNA in their gut contents.