Effects of different photoperiods on the reproduction of the barbel, Barbus barbus (L.), reared at constant temperature |
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Authors: | P. Poncin |
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Affiliation: | University of Liège, Department of Animal Ethology. Research Unit on Fish Demography and Experimental Fish Culture, 22 quai Van Beneden, B-4020 Liège, Belgium |
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Abstract: | The role of photoperiod as an environmental factor controlling reproduction, particularly the duration and ending of the breeding season, in the barbel was investigated by tank experiments. The experiments used a population of barbel matured in captivity which were stripped of eggs at frequent intervals: 10–15 'spawnings'for each female were obtained at 15-day intervals. A decreasing photoperiod (16·5 light: 7·5 dark→8L: 16D), for an annual cycle contracted to 6 months duration, inhibited the spawning of both female and male fish. This allowed two periods of reproduction (February-May and September-November) within one year. Under natural or constant (10L: 14D) photoperiod conditions, spawning came to an end spontaneously. The rate (accelerated, slow or natural) of daylength increase did not affect the onset of spawning. |
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Keywords: | photoperiod Barbus barbus reproductive cycles aquaculture (light effects) |
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