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The Steady Decline of Hamana Lake Clams - Japan's Search for a Circular Economy (May 2001) In May 2001, clam resources in Hamana Lake, Shizuoka Prefecture, were in steady decline, severely impacting the local aquatic environment. Once abundant, the clams had rapidly declined due to the cumulative effects of deteriorating water quality since the 1990s, domestic wastewater discharge, red tides, changes in bottom sediment, and overfishing. This decline heightened a sense of crisis among fishermen. Lake Hamanako possesses a delicate brackish water environment connected to the Enshū Coast. When the ecosystem's balance is disrupted, organisms like bivalves are among the first to be affected. Consequently, their decline became a crucial indicator symbolizing environmental change.

The year 2001, when this article was published, coincided with a period when building a recycling-oriented society was emphasized as a national policy goal. Waste reduction and resource recycling were being discussed at the national level. The decline of Hamanako's clams was highlighted within this context as a concrete example for considering resource sustainability. Local governments and fishing cooperatives advanced countermeasures such as water quality improvement, tidal flat restoration, and juvenile clam cultivation, emphasizing the need to reexamine the relationship between nature and the local community. The situation in Lake Hamana became a symbolic case study where a local environmental crisis was linked to the national challenge of building a recycling-oriented society. I remember the late 1970s (early Showa 50s): large clams were plentiful in the shallow waters, about 120 centimeters deep, at Kanzanji Beach. You could harvest them just by digging with your feet wh
ile treading water. Along the shore, cherry shells could be gathered, and when fishing by boat, wild oysters formed clusters on the rocky outcrops exposed at low tide. This abundance was not metaphorical; it was an everyday sight.

Near the National Hospital, there was a pear orchard where we could gather astonishing numbers of cicada nymphs. Along the stream beside the approach to Okuyamadera Temple, stream crabs were so numerous they were visible without even searching. Around Lake Sanaru, despite being a residential area, the great chorus of cicadas resounded. It was an era when pollution was becoming a major social problem, yet it was also a time when one could physically feel the vitality and density of nature.