Since being closed to the public, Oamaru's historic Sumpter Wharf has become a breeding colony for an endangered and little-known species of shag.
Dr Chris Lalas
And with the Waitaki District Council now investigating reopening the 200m-long wharf to the public, scientists who know the birds are concerned.
Dunedin-based researcher Dr Chris Lalas, who has been studying shags for the last 40 years, first discovered Otago shag nests at the wharf in 2014.
"If it gets opened up to the public, it will totally destroy it as a shag location,'' Dr Lalas said.
Human use and an Otago shag breeding colony were "not compatible''.
Like the more common spotted shag, which are also a common sight on the wharf, it was believed Otago shags only roosted at the wharf and he was surprised to find them breeding there.
In 2015, he counted 235 nests at the wharf.