Effects of Photoperiod on the Reproductive Success of Fathead Minnows

by John B. Clayton. Nick C. Parker, Jimmy D. Winter,and Clifford B. Fedler

The reproductive cycle of fishes depends on environmental factors such as photoperiod. Because of photosensory organs like the pineal gland and hormones like melatonin, it is believed that photoperiod length directly influences the reproductive cycle. Manipulation of this cycle can allow for higher yields and more marketable products in the practice of aquaculture. "Night-interrupted" experiments can be used to show the effects of photoperiod on reproduction. A series of 15minute light pulses will be introduced to the scotophase (night) of fathead minnows in order to study the effects of photoperiod manipulation on their reproductive cycle.In addition to the "night-interrupted" experiment, we will also look at the effects of different photoperiod lengths on the reproductive cycle of fathead minnows. We will place fish under a series of artificial photoperiods ranging from a 6 hr day and a 6 hr night to 16 hr day with an 8 hr night. By placing these fish under different photoperiods, we will be able to investigate whether or not the actual number of daylight hours and night-time hours effect their maximum reproductive success.

In Research Highlights - 1996, Vol. 27. Texas Tech University, Department of Range, Wildlife and Fisheries Management.

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