The blue crab catches increased rapidly in Miyagi-ken, was it the influence of a tidal wave by an earthquake disaster?

Recently the NHK On-line reported the following:

ワタリガニ漁獲量 宮城県内で急増 震災の津波が影響か

5月18日 9時05分

みそ汁などの具材に使われる小型のカニ「ワタリガニ」の漁獲量が東日本大震災以降、宮城県内で増え続けていることがわかり、専門家は「震災の津波によって宮城県沿岸の海底に泥が流れ込み、カニが生息しやすい環境になったことが要因の１つではないか」と分析しています。

ワタリガニは「ガザミ」とも呼ばれる体長が１５センチほどの小型のカニで、みそ汁やパスタに入れたり、そのままゆでたりして食べられます。

宮城県内の漁獲量は、震災前は年間１０トンを下回る程度でしたが、震災の翌年に３０トン余りに増え、３年前には５００トンを超えて全国１位となりました。

さらに、おととしには６６０トン余りと、全国のおよそ３割を占めるまでになっていて、石巻市などでは、ワタリガニ漁に参入する漁業者も目立ち始めています。

こうした状況を受けて、宮城県は今年度からワタリガニの生態などの詳しい調査を行うことになりました。

宮城県水産技術総合センターの山崎千登勢技師は「ワタリガニの急増には驚いている。海水温が上昇したことに加え、震災の津波の影響で沿岸部の海底に泥が流れ込み、冬眠するカニにとって生息しやすい環境になったことも要因の１つではないか」と話しています。

Translation

  

It was understood that the catches of small crabs, the "Blue crab" which was used in miso soup as ingredient material, was increasing in Miyagi-ken after the Eastern Japan Great Earthquake. A specialist analyzed that "may be one reason is that mud had flowed in at the bottom of the sea to Miyagi-ken coast due to a tidal wave of an earthquake disaster; and the environment was easy for crabs to live."

The "Blue crab", also called the "swimming crab", was a small crab that had a body length of about 15 centimeters; it could be added to miso soup and pasta, or it could be boiled just as it was and be eaten.

Before an earthquake disaster the catch in Miyagi-ken was to the extent of below 10 tons a year, but it was increased to about 30 tons in the year after earthquake disaster; 3 years ago it was at the 1st place in the whole country reaching over 500 tons. Furthermore, two years ago it was about 660 tons and was approximately 30 percent of the whole country. In Ishinomaki-shi etc. fisherman who joined the catching of blue crabs had begun to be noted.

Miyagi-ken in view of such a situation conducted a detailed investigation on the ecology of blue crabs from this fiscal year.

Yamasaki Chitose the engineer in Miyagi-ken marine technological integrated center said that "A rapid increase of blue crab is astonishing. Beside the rising seawater temperature, it is the influence of a tidal wave of an earthquake disaster that made the mud flow into the bottom of the sea in coastal areas; one factor is that for those crabs that do hibernation, the place becomes an environment easy to live.”

I am wondering whether or not the water in the region could have been contaminated by some radio-active water.