After the release of documents that gave a hint that the US Fish and Wildlife Services have allowed to kill 11,000 double-crested cormorants irrespective of the fact that the measure would not help save threatened fish populations, conservations have demanded an investigation in the matter.

In April, five conservation and animal welfare groups have filed a lawsuit in April, so that the native cormorants should not be killed that live on East Sand Island near the mouth of the Columbia River Basin in the US Pacific Northwest.

Last week, under a court order a Fish and Wildlife report from 2014 was released. As per the report, if the cormorants would not be present then other predators will eat salmon and steelhead. Bob Sallinger, conservation director of the Audubon Society of Portland, was of the view that federal agency has made decisions that contradicted its own research.

A US Fish and Wildlife spokeswoman said that she cannot comment on the report due to pending litigation. The government came up with a plan to cull the birds after the National Oceanic and Atmospheric Administration released a paper stating that there is a need to reduce the population of cormorants to under 6,000 breeding pairs from around 13,000 by 2018.

The lawsuit states that the government has not tried non-lethal methods to control the bird's population. "The agency's own analysis makes clear that its cormorant-killing program is doing nothing to help endangered fish. ... The killing needs to stop now", said Collette Adkins, attorney and biologist at the Center for Biological Diversity.