Spanish police began their probe in March 2015 after being tipped off by the agriculture and environment ministry that a group of shipowners based in the northwestern region of Galicia were frequently violating fishing rules in Spain and abroad.

"It has been established that they may have illegally captured over 3 500 tons of Antarctic toothfish," the statement said.
The ring is estimated to have made a profit of over $11.3 million per season from the illegal fishing operation.

Antarctic toothfish, also known as Patagonian toothfish or Chilean Sea Bass, is a large, slender fish found in the cold, deep waters of the southern hemisphere whose soft flakiness makes it a popular seafood in the United States and Japan.