de VLAMING: CONTROL OF REPRODUCTION IN GILLICHTHYS 



uation. Unfortunately, no data are available 

 on the effects of exogenous factors on the fre- 

 quency of spawning, fecundity, egg size, or sur- 

 vivorship of the fry in this species, nor are data 

 available on the influence of environmental fac- 

 tors on the spawning act. For a complete under- 

 standing of the role of the environment in the 

 physiology and ecology of reproduction in Gil- 

 lichthys, examination of these parameters is 

 needed. 



The data presented here indicate that temper- 

 ature may be the proximate factor regulating 

 the Gillichthys reproductive cycle. Zambrano 

 (1971) found that the secretory activity of the 

 pituitary gonadotrophic cells is altered by tem- 

 peratures, and this provides further support for 

 this suggestion. However, since fish in their 

 natural habitat experience large diurnal temper- 

 ature fluctuations, the experiments reported here 

 are not conclusive. In addition, Gillichthys is 

 capable of regulating its body temperature by 

 behavioral means (de Vlaming, 1971a). These 

 experiments do set the physiological limits with 

 regard to the influence of temperature on 

 reproduction. Understanding the ecological 

 meaning of temperature in reproductive cycling 

 requires experimentation with diurnally fluctu- 

 ating temperature; experiments of this nature 

 are reported elsewhere (de Vlaming, 1972c), 



ACKNOWLEDGMENTS 



I am particularly indebted to Dr. Paul Licht 

 for his continued interest and encouragement in 

 this research. I am grateful to Dr. Licht and 

 Dr. George Barlow for reading an initial draft 

 of this manuscript and making many insightful 

 suggestions, JoNell Biancalana also deserves 

 special thanks for her assistance and encourage- 

 ment in this research, 



I appreciate the assistance of Geraldine Ard 

 and Abbey Reeder in typing this manuscript 

 and Emily Reid in preparing the figures pre- 

 sented herein. This work was supported in part 

 by a research grant from the Graduate Division 

 of the University of California and a National 

 Institutes of Health predoctoral fellowship. 



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