Grass Carp Thermal Maturation and Proximal Cues for Spawning in Ponds

Session: Poster session

Jeffrey Jolley, U.S. Geological Survey, [email protected]
Duane Chapman, USGS, [email protected]
Curtis Byrd, Lynxnet, LLC, [email protected]
Patrick Kocovsky, U.S. Geological Survey, [email protected]

Abstract

Grass carp (Ctenopharyngodon idella) reproduction has occurred in the Lake Erie basin; understanding recruitment requirements and cues for spawning could be useful in designing control methods and will help determine which Great Lakes tributaries are potential spawning locations.  Grass carp are broadcast spawners that require flowing water to keep their eggs suspended, however spawning cues are unknown. At least 633 cumulative degree days ? 15 ºC (ADD15) has been reported necessary for maturation.  To validate this estimate, we intermittently evaluated maturation in ponds.  The first female with ripe oocytes had experienced over 800 ADD15, 7 days after 633 ADD15 was attained.  Estimated threshold for 50% of female grass carp to have ripe oocytes was 906 ADD15.  We designed a pond mesocosm to simulate river conditions and variable spawning cues (i.e., flow, turbidity, temperature).  Successful spawning during the first trial, when fish were injected with hormones (HCG, carp pituitary), was confirmed by spawning behavior recordings (chasing, rubbing) and the presence of fertilized eggs.  Grass carp did not spawn in additional trials but water temperatures may have increased beyond the suitable range.  Future trials will focus on replicating the results of trial one, tightening temperature control, and further variation of environmental cues

1. Keyword
carp

2. Keyword
recruitment

3. Keyword
invasive species

4. Additional Keyword
reproductive ecology

5. Additional Keyword
grass carp

6. Additional Keyword
mesocosm