1Shiga Prefecture Fisheries Experiment Station, Hikone, Shiga 522-0057, 2Nikko Station, Freshwater Fisheries Research Division, National Research Institute of Fisheries Science, Fisheries Research Agency, Nikko, Tochigi 321-1661, 3Ueda Station, Freshwater Fisheries Research Division, National Research Institute of Fisheries Science, Fisheries Research Agency, Ueda, Nagano 386-0031, Japan
Relationships between growth variability and environmental factors were examined for larval and juvenile ayu Plecoglossus altivelis altivelis in Lake Biwa from 2008 to 2010. The back-calculated daily growth rate of larval and juvenile ayu through otolith microstructure analysis was positively related with the water temperature and the zooplankton density. Mean growth rate from hatch to December was lower in the year with a high egg production of ayu. These results suggest that water temperature, zooplankton abundance and population density are all important determinants of growth of larval and juvenile ayu. The catch of ayu by set nets in the first period of the fishing season seemed to be affected by interannual growth differences of larval and juvenile ayu.