The ocean current
Penghu is surrounded by the ocean with clear water and both the North Shallow Fishing ground in the north and the South Shallow Fishing ground in the south. Also with the branch of the Japan current [ the Kuroshio ] passing by, it has been a great natural fishing ground since long ago. The main ocean currents are:
The China coast cold current: this coast cold current influences mostly the west side ocean area of Penghu. It is originates from the north of the Yellow Sea and flows along the east coast of Chinea toward south. With a large amount of water pouring into, this current is quite strong especially in summer with the rainfall and contains little salt. In winter, this current is strengthened by the northeaster wind and the water temperature is lower than the Japan Current. In summer, the southwest wind makes it weaker and the water temperature is similar to the Japan Current. In winter, fish swims toward south along with this current and gather up at the west side of Penghu.
The branch of the Japan Current: the main stream of the Japan Current flows toward north along the east coast of Taiwan with its branch flowing passing the Bashi Channel and entering the South China Sea to form a counter clockwise current; the other part of the branch turns to flow along the west coast of Taiwan toward north and reach the Penghu area, and then flows further to meet the Japan Current. Stopped by the northeaster wind, this current mostly flows to the South China Sea and only little part of it flows into the Penghu ocean area. With the summer southwest wind strengthening this current, it mostly flows into the Taiwan Strait and both the water temperature and the salt contained are higher than the other two ocean currents. Therefore it can bring fishes that come from tropical Pacific Ocean and the Indian Ocean in summer.
The South China Sea Monsoon Current: in winter, one branch of the Japan Current and the China coast cold flow go together into the Penmghu area and form a counter clockwise current which makes the South China Sea monsoon current influences nothing in this area. In summer, with strong southwest monsoon blowing, this current flows into Taiwan Strait and turn toward northeast. Therefore this current possesses rich rainfall and river water with it. Generally speaking, in July, the Penghu area is influenced more by the branch of the Japan Current and the South China Sea Monsoon Current. With various cold and warm currents meeting here, a large number of plankton is produced and this provides rich food for great aount of fishes.