Evaluation of Calcein and Photonic Marking for Cultured Delta Smelt

Abstract

The Delta Smelt Hypomesus transpacificus is a protected osmerid endemic to the San Francisco estuary of California. We conducted laboratory tests on marked versus unmarked juvenile adult smelt to evaluate (1) calcein mark intensity and postmarking survival for juveniles and adults, (2) photonic mark retention and survival of adults, and (3) predation by juvenile Striped Bass Morone saxatilis. Calcein mark intensity was graded in six body sections and adults were photonically marked using four fin-color combinations. Across all immersion times (1–7 min) all fish showed 100% mark retention 7 d after exposure to calcein concentrations of 2.5 and 5.0 g/L of water. Average survival 7 d after calcein marking was 93.9% in juveniles and 98.6% in adults. After 97 d of calcein and photonic marking, adults had weaker double marking, but each type of mark still showed 100% retention. Average survival of adult fish 70 d after marking was 98.7%. Unmarked and calcein + photonically marked adult Delta Smelt exposed to juvenile Striped Bass did not experience significantly different predation rates. Calcein is both effective and practical to batch-mark juvenile and adult Delta Smelt. Combined calcein and photonic marking for adult Delta Smelt further enables identification of multiple groups while potentially improving mark detection in short-term studies.

Received October 1, 2012; accepted August 22, 2013

Published online January 14, 2014

ACKNOWLEDGMENTS

Volunteers from the California Department of Fish and Game, U.S. Fish and Wildlife Service (USFW), and University of California Davis provided valuable assistance conducting marking and predation tests. U.S. Bureau of Reclamation (USBR) biologists led by Brent Bridges (Rene Reyes, Michael Trask, and Brandon Wu) greatly helped with photonic marking. Don Portz (USBR), Anke Mueller-Solger (California Department of Water Resources [DWR]), and Tim Matt and Bill Beckett (California Department of Fish and Wildlife) were instrumental in the predation tests. Paul Cadrett and Kim Webb (USFWS), and Ted Sommer (DWR) provided useful comments. This project was funded by the Delta Science Program, USBR, and USFWS. The findings and conclusions of this study are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. Reference to trade names does not imply endorsement by the U.S. Government.