LONG BEACH, CALIFORNIA — Disturbing footage of a shark being bludgeoned by a fisherman has lead to increased calls for a ban on drift gill nets in commercial fishery.

The Mercury News reports that the video was taken by an undercover activist and posted online by Mercy for Animals, and comes as two California senators introduced a bill to ban the nets nationwide.

Drift gill nets are long walls of meshed synthetic netting held vertically in the water by floats along the top and weights on the bottom.

According to the United Nations Food and Agriculture Organization, fish are caught when their gills get stuck in the mesh openings, the sizes of which vary depending on the type of fish being targeted.

But non-target animals, called bycatch, are also captured. Sharks, dolphins, and sea lions often get tangled in the net and are unable to free themselves, leading to death or serious injury.

Drift net fishermen claim the industry has implemented measures to reduce bycatch, including using nets with larger openings and electronic devices to scare off dolphins.

Still, opponents say the casualties are unnecessary and unacceptable, believing that phasing them out is the best way to stop the horror.