群馬縣高崎市榛名湖今年無冰上釣魚

Late last month the Yomiuri News on-line reported the following:
　群馬県高崎市の榛名湖のワカサギ穴釣りについて、榛名湖漁業協同組合（野口正博組合長）は２８日、放射性物質検査の検体にするワカサギが１匹しか釣れず、安全が確認できないとして今季は解禁しないことを決めた。
　組合員らは昨年９月からワカサギの捕獲を約２０回試みてきた。しかし、まったくかからず、この日、県と市の職員も加わり８５人が約５時間半、氷上から釣り糸をたらして、ようやく１匹が釣れた。
　漁協は「少なくともこの１０年でこんな不漁はなかった。理由は全く思い当たらない」としている。
　漁協によると、検査には検体が２００グラム（５０～１００匹相当）が必要で、漁協は検査自体を断念した。
　榛名湖は都市部から近く、氷上のワカサギ穴釣りは冬のレジャーとして人気がある。通常は湖が全面結氷する１～３月に行われる。
(試譯文)
After noting that there was only one lake smelt made available as the sample for inspecting the radioactive material, and that the checking for the safety of the lake smelt in the Haruna lake in Takasaki city, Gumma could not be carried out, the Haruna lake fisherman's cooperative association (union president Masahiro Noguchi) decided on the 28th that the ban would not be removed this season.
Union members had tried to capture a pond smelt for about 20 times since September last year, but to no avail; the personnel from the prefecture and the city also joined on that day; 85 people hang down the fishing line for about 5.5 hours from above the ice, and was able to get one fish at last.
The fisherman's cooperative association expressed that "there was no such poor catch at least in the past ten years. The reason for that could not be figured out at all."
According to the fisherman's cooperative association, 200 g (50 - 100 fish) was needed for the sample inspection, and the fisherman's cooperative association gave up the self inspection.
Haruna Lake was near the urban area, to fish pond smelt above the ice from a hole was a popular leisure in the winter. Usually, it would be held from January to March when the lake was frozen completely.

I am also interested to know why there was so few lake smelt this year.