(search for Biwa in text)
I've been reading your link via translation, first, Sankei is relatively ultra-right, and would aim to neglect mention of lake pollution, blaming the issue instead on the Chinese. But if you follow the Chinese pearl industry, Chinese pearl quality was terrible in the 1970s and 1980s, often being described as "rice krispies" due to their baroque appearance and small size, and could not possibly compete with Biwa. All other sources cite either pollution or increasing environmental regulations as having killed the Lake Biwa industry.
At this point, others mocked your claims of being a critical thinker, and I am now, disappointingly, beginning to suspect bigotry on your part myself. I'm not here to join the lynch mob, so I'll let the others handle this.