The cull involved two half days of shooting last week and a full day this week, Marian Stranak, superintendent of Point Pelee National Park told the Windsor Star Wednesday night.
While Parks Canada said 72 cormorants were killed last week, Stranak said she didn't know how many were killed Monday, the last day of shooting.
Neither the media nor protesters were allowed to witness the cull, although Liz White of Animal Alliance and Cormorant Defenders International told the Star 315 shots were counted offshore.
Parks Canada claims it needs to reduce the bird population on the uninhabited island because the colony's guano was threatening its Carolinian ecosystem that includes rare trees including Kentucky coffee trees, red mulberries and blue ashes, the newspaper said.
Notable deaths of 2014 [PHOTOS]