Many famous fishing grounds are built in waters with significant upwelling, such as the Thousand Islands Fishing Ground in Russia, the Newfoundland Fishing Ground in Canada, the Peruvian Fishing Ground in Peru, and the Zhoushan Fishing Ground in China. Why is this?
It turns out that while upwelling brings cooler bottom seawater to the sea surface, it can also bring a large amount of nutrients in deep water, such as phosphates and nitrates, to the surface, becoming nutrients for phytoplankton, causing a large number of phytoplankton reproduction. The massive reproduction of phytoplankton provides abundant bait for zooplankton, thus attracting more fish.
According to statistics, the average primary production of the upwelling area (organic matter produced by green plants through photosynthesis per unit of time and per unit area) is about 300 g/m^2·year (carbon), which is three times that of non-upwelling coastal areas and six times that of oceanic areas. Average plankton production in upwelling areas is also high, ranging from 20 to 60 mg/m^2·day (carbon), which is twice that of non-upwelling coastal waters. Fish production in the upwelling area is very high. According to estimates, the area of the upwelling area only accounts for 0.1% of the world's ocean area, but the catch accounts for half of the world's total marine fish production.