Was environmental pollution the only reason for the collapse of the Biwa cultured pearl industry ?
The Biwa Pearly Mussel is a species of Unionidae mussels endemic to the Lake Biwa and its satellite lakes, in the Shiga prefecture of Japan. The lake was also host to many endemic fish species, that served as hosts to the glochidia larvae of the pearl mussels, which was crucial for the completion of their life cycle. The mussel is long lived with a life span of over 40 years, and was the first freshwater mussel in the world to be exploited for artificial pearl culture. The human population that inhabited the immediate surroundings of the lake was 1.3 million. The Biwa pearly mussels were harvested and the mature mussels (shell size greater than 7 cm) were tissue implanted before returning to the water to begin the culturing process, that lasted from 1 to 2 years. In the early 1970s the catch of mussels were over 10 metric tons (10,000 kg), which was maintained with minor fluctuations until the early 1980s, after which production decreased drastically to less than one metric ton in the
