BROWNSVILLE – In the pitch black of night, Texas Game Wardens hunt for illegal gill nets along the Rio Grande.

The nets can stretch from Mexico to the United States trapping, killing fish; cutting into a dwindling supply.

Not only do officials hunt in the dark with lights turned off, they push their patrol boats near their limits.

Even with a three boat operation, when they come across gill netting they stay alert knowing there might be smugglers nearby.

The gill net that gets pulled out is lined with a number of fish: spotted trout, red drum, mullet and crabs; all stuck in the plastic netting.

“There's no fish in Mexico. There's just abundance of these commercial fishermen. There's no rules. There's no regulations. There's no possession limits. There's no size limits. And the demand is there. So they risk going offshore. Going as far as Corpus [Christi] and setting their longlines. Or setting their nets in our river,” said Game Warden Ira Zuniga.

Game Wardens can’t remove the whole line. Part of the river belongs to Mexico, so they have to cut it halfway across the river and leave the rest.

To report illegal fishing activity, call the Texas Game Wardens at 1-800-792-4263.

Watch the video above for the full special report.