Animal rights group Compassion Over Killing (COK) went undercover at Cooke Aquaculture's operations in Bingham, Maine -- an Atlantic salmon hatchery that supplies to Martha Stewart's True North Seafood line -- and has published troubling footage in a disturbing video that shows workers stomping on the heads of salmon.

The group claims its video, which was released publicly Monday, "takes you beneath the surface of the factory farming of fish, revealing putrid conditions breeding disease and parasites as well as widespread cruelty to fish intensively crowded in barren tanks."

The group submitted a complaint over what it shot in its undercover footage to the Maine Department of Agriculture in September, according to Cooke. The Canada-based salmon giant was alerted about the video on Sept. 16, however, was unable to view the footage until this week, it said.

"Based on information received from the department, and after reviewing the footage issued today by the activist veganism organization, it appears that unacceptable fish handling incidents have occurred at the Bingham hatchery," CEO Glenn Cooke said in a statement. "These are not our standards and will not continue."

The company posted a detailed apology statement on its website Monday.

Compassion Over Killing has aggressively promoted the video across social media channels.

Its Facebook following numbers over 680,000, while its Twitter network has over 46,000 followers.

The company did not disclose how it conducted its investigation. Compassion Over Killing was passed over as a top recommended charity by Animal Charity Evaluators, primarily because of a lack of transparency as to what it does with its funding. Compassion Over Killing declined to be reviewed, according to Animal Charity Evaluators.

The activist group also runs the vegan promotional site, which is endorsed by the seafood, plant-based alternative company Good Catch.