2006/07/24 by C. Gillet, P. QuéTin, Philippe Quétin · 3 citations
Environmental Science · Agricultural and Biological Sciences · #Fish Ecology and Management Studies #Fish Biology and Ecology Studies #Marine and fisheries research
paper · doi:10.1111/j.1095-8649.2006.01123.x
In Lake Geneva, the surface water temperature has increased by 1° C over 20 years probably as a result of climate change. The effects of changes in temperature on the reproductive cycle of the roach Rutilus rutilus were assessed in a 19 year survey. Over time, spawning tended to begin earlier. The consequences of temperature changes were assessed on two different stages of the female reproductive cycle: the development of the ovaries from the beginning of autumn to ovulation, and the onset of the spawning period. The development of the ovaries was studied for 7 consecutive years from October to June. From 1 October to the onset of spawning, it was possible to assess the gonado‐somatic index ( I G ) of females in terms of time expressed as a sum of degree‐days. The correlation between I G and the sum of degree‐days was +0·97. The onset of the roach spawning period in Lake Geneva was triggered by a thermal threshold (median and range 190 ± 10 degree‐days for the 15 previous days). From October to April, climate warming accelerated the development of gonads, then in May, a thermal threshold that triggered the onset of roach spawning occurred earlier.