Katia Deng/ Shanghai Daily news

More than 2,000 Chinese sturgeons were released into the mouth of the Yangtze River yesterday to mark World Earth Day which falls on April 22 every year.

The event was the first ever aimed at protecting a rare aquatic species such as the Chinese sturgeon and mullet.

Shanghai plans to spend 10 million yuan (US$1.30 million) every year to buy the rare fish and releasing them into rivers, said an official from local aquatic product bureau.

World Earth Day was first observed in the Spring of 1970 in the US.

On April 22, 1990, on the 20th anniversary of the event, more than 200 million people in 141 countries participated taking action to protect the environment to celebrate the day.

Now, events to commemorate the day have become more formal, with professional organizing and specific interests.