Fish form an important part of the daily diet for many people.
But a growing world population has led to increased fishing and a massive depletion of stocks.
It is estimated 30 percent of the world's ocean fish stocks are depleted, overexploited or recovering from overfishing.
Bluefin tuna is one fish particularly badly affected. Supplies have depleted by 96 percent in the north Pacific Ocean.
Al Jazeera's Andrew Thomas reports from south Australia.