OTSU, Shiga Pref. — The Shiga Prefectural Government has embarked on an ambitious plan to regulate leisure activities on Lake Biwa, a water sports mecca and the largest single source of drinking water for the Kansai region.
The prefectural assembly is currently deliberating a draft ordinance that would ban catch-and-release of foreign fish species and the use of two-stroke engines on the nation’s largest lake, although no penalties are planned for violations.
A vote on the ordinance is to be taken before the legislative session ends Oct. 16.
According to the prefecture, some 750,000 sport fishermen visit the lake annually. Of this figure, 700,000 are thought to come for black bass, one of the foreign species blamed for the declining catch of the lake’s indigenous fish species. Usually, bass anglers return the fish to the lake after catching them.
Traditionally, plenty of fresh-water fish such as carp and gibel — renowned in the local cuisine — could be found in the lake. But the indigenous species, especially those that breed near shore, have been overwhelmed by their foreign counterparts, namely black bass and bluegill, both of which eat other fish.
“The ecosystem of the lake, which can be traced as far back as 400,000 years, has been rapidly damaged in recent years,” prefectural official Yutaka Shibamiya said. “Foreign species make up about 90 percent of the fish caught in the southern part of the lake, with bluegill comprising 90 percent (of that amount) and black bass the remainder.”
He added that catches of the main indigenous fish species have dropped by 80 percent to some 200 metric tons in the last 20 years.
The prefectural government estimates that some 3,000 metric tons of the foreign fish — 2,500 of bluegill and 500 of black bass — now live in the lake.
“The decline of the original species coincides with the rise of black bass and bluegill,” said Katsuki Nakai, a research scientist at Biwako Museum who studies fish and their habitats. “They are one of the reasons for smaller fish catches, to say the least.”
Anglers say that black bass should not be blamed for the decline of the indigenous species as there are far more bluegills in the lake. However, Nakai counters that black bass still have an edge over bluegill in the northern part of the lake, and that black bass eat far more fish than bluegill.
But the prefecture is not concerned with such specifics.
“No matter which fish is responsible for the decline of the original kinds, the present state of the fish ecosystem in the lake is clearly distorted,” official Shibamiya said. “Banning the release of the foreign fish is part of our effort to preserve Lake Biwa and pass it on to the next generation.”
Although there will be no penalty for releasing catches, a member of a major bass-fishing group said on condition of anonymity that most bass anglers would probably comply once the ordinance is enacted because violations could lead to tougher regulations and penalties.
“But the number of visitors to the lake will drop to about one-third,” he predicted.
The ban on two-stroke engines, meanwhile, stems largely from complaints by local residents who are fed up with the noise of jet skis.
The ordinance would forbid any pleasure boats and other craft with such engines from running on Lake Biwa after April 2008. Currently, such craft are bound only by a safety ordinance and are virtually free to come and go except in one area near a beach.
Shibamiya of the prefectural government said that although two-stroke engines emit far more toxic substances than four-cycle ones, they do not exceed environmental limits. Therefore, the proposed ordinance would carry no penalty for their use.
But he noted that engine noise at several spots along the lake exceeds the environmental limit of 65 decibels.
Therefore, the proposed ordinance would designate certain areas as regulated water zones to protect the living environment, with a breach of these zones bringing a maximum 300,000 yen fine.
However, Tetsuya Inoue, representative of the citizens’ group GreenWave, said the proposed ordinance does not guarantee any improvement in Lake Biwa’s ecology.
“Whether two-stroke or four-stroke, water craft should be banned altogether because they generate noise and unpleasant emission smells for residents,” said Inoue, who has a home in the lakeside city of Hikone.
“During the summer peak, when more than 100 jet skis are out on the lake, I cannot open my windows because the emissions come as far as a few hundred meters inland.”
“They need not be driven on Lake Biwa, which supplies water to most of the Kansai region.”
Inoue also thinks that visitors’ manners cannot be expected to improve with the ordinance because “they come to Lake Biwa for fun, not for nature conservation.”
“The prefectural government can do a lot more to protect the lake if it thinks it is responsible for it,” as it is a water source, he said. “You cannot change the water of the lake right away. It is enclosed water.”