Spawning and Hatching of Endangered Gila Chub in Captivity

Abstract

Information on reproductive characteristics of the endangered Gila Chub Gila intermedia is largely limited and qualitative, and culture techniques and requirements are virtually unknown. Here we provide the first published data on spawning and selected reproductive and developmental characteristics of Gila Chub. Fish were brought to the laboratory in March 2003 from Sabino Creek, Arizona (12.3°C). Fish were then warmed slowly and spawned at 14.9°C, 10 d after collection. Following this initial spawning, Gila Chub spawned consistently in the laboratory without hormonal, chemical, photoperiod, temperature, or substrate manipulation during all times of the year. Spawns were noted at temperatures ranging from about 15°C to 26°C; however, we noted that Gila Chub spawned less frequently at temperatures above 24°C. Multiple spawning attempts per year per individual are probable. There was a strong, inverse relationship between time to hatch and incubation temperature. The hatch rate of eggs was high (mean = 99.43%), and larval Gila Chub accepted a variety of natural and formulated diets at first feeding. The future of Gila Chub may someday depend in part on hatchery propagation to provide specimens for restocking formerly occupied habitats and establishing refuge populations. Information from our study can aid future efforts to successfully spawn and rear Gila Chub and related species.

Received November 5, 2015; accepted February 26, 2016

Acknowledgments

We thank staff at the Arizona Game and Fish Department (AGFD); U.S. Fish and Wildlife Service, Bureau of Reclamation (BOR); New Mexico Game and Fish Department, Bureau of Land Management (BLM); and Arizona Sonora Desert Museum (ASDM). We thank the U.S. Forest Service (USFS) and staff associated with the USFS Santa Catalina Ranger District. Special thanks to Jeff Simms of BLM and Craig Ivanyi and Ken Wintin of ASDM. Special thanks to Courtney Conway, Kevin Fitzsimmons, Peter Reinthal, and Cecil Schwalbe for their guidance and support. We thank all students, staff, and faculty at the University of Arizona (UA) and the U.S. Geological Survey’s (USGS) Arizona Cooperative Fish and Wildlife Research Unit (ACFWRU) who assisted in any respect during this study. We thank Roger Sorensen and Kirk Young of AGFD and Rene Reyes of BOR for their reviews. Listed affiliations are those during the time period of the study. This project was funded by the AGFD Heritage Fund, the Central Arizona Project Transfer Fund, the UA, and the USGS/ACFWRU. The views expressed are those of the authors and do not necessarily reflect the views of the USGS or ACFWRU. The mention of specific products does not constitute endorsement by any agency or employee thereof.