Author
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Davis Jr, Kenneth |
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Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/20/2009 Publication Date: 5/29/2009 Citation: Davis Jr., K.B. 2009. Age at Puberty of Channel Catfish, Ictalurus punctatus, Controlled by Thermoperiod. Aquaculture. 292:244-247. Interpretive Summary: Channel catfish populations usually do not mature until they are three years old. There is controversy concerning the induction of puberty whether age, size, photoperiod, or annual temperature cycles are the most important signal in inducing puberty. In this study, 73% of two year-old Channel catfish were induced to spawn by exposure to three alternating temperature cycles compared to 10% of two year-old fish raised in a pond and exposed to two annual temperature cycles, and 3% of fish raised indoors at constant high temperatures. Fish exposed to the shortened temperature cycles were similar in size to those from the pond and both weighed significantly less than those raised at constant high temperature. The number of annual cycles appears to be the crucial environmental cue that induces puberty and size of fish appears to be relatively unimportant. Technical Abstract: Channel catfish held under a shortened annual temperature cycle of four months of warm water followed by two months of cold temperature spawned at a higher rate (73%) after three temperature cycles than fish held in outdoor ponds on two normal seasonal temperature cycles (10%) and fish raised in tanks supplied with constant warm water (3%). Fish held in constant warm water were about twice as heavy as fish from the other two groups. Spawns from tank raised fish were significantly heavier than spawns from fish held in ponds and the shortened annual temperature cycled fish. These data suggest that the onset of the first reproductive period (puberty) is a developmental event that requires three cycles of warm and cold periods, and that weight and photoperiod have little influence on the onset of puberty. |
