fish farm

The extraction of groundwater, a practice often used in fish farms, is sinking land and contributing to rising sea levels cites a recent study published in Geophysical Research Letters.

Coastal land can compact after water is sucked out for use in fish farms, creating a condition called coastal subsidence, reports Modern Farmer. And in China, along the Yellow River Delta, “The subsidence is causing sea levels to rise nearly 100 times faster than the global average. The delta is dominated by aquaculture and has experienced severe coastal erosion (up to 25 centimeters a year).”

Farmed fish has become big business in recent years, putting pressure on wild fish populations both for space and with health threats such as parasites and diseases. The fish can escape from some fish farms and throw off the balance of certain species. And just like land-based livestock, waste from fish farms is a contributing factor to ocean pollution that can devastate marine ecosystems.

Nearly 90 percent of the world’s farmed fish comes from Asia, reports Modern Farmer, and in China, fish farms “were built along the coastline of the delta starting in the 1970s, and by 2001 over 250 billion gallons of groundwater were extracted a year.”

And the pressures are just increasing as roughly one-third of the world’s fish and seafood now comes from aquaculture, with fish farms quadrupling in the last twenty years.

Warming waters and melting ice caps are known threats contributing to rising global sea levels. As the sea levels rise, storms and floods can increase in frequency and intensity and shorelines are more at risk of retreating.

But experts suggest that land subsidence from groundwater extraction practices may be creating more severe and immediate dangers to coastal stability than the environmental effects causing global sea levels to rise.

Keep in touch with Jill on Twitter @jillettinger

Image: Robert Couse-Baker