Those who had worked with him praised his enthusiasm, sense of humour and eagerness to share his expertise, through his research, photography, writing and presentations.
"He has the ability to communicate his passion for the marine world and to translate scientific information in a way that is easily understood by the public," Mr Dunlop said.
"Over the last 46 years he has worked as an independent consultant in marine biology and ecology for clients including government departments, regional councils, port authorities, private businesses and non-government organisations, mostly in New Zealand but also overseas.
"Among his more recent projects, Roger has been highlighting the ecological value of mangroves in New Zealand's north and working to get permanent protection for the Bay of Plenty's Astrolabe Reef, where the remains of the container ship Rena lie."
He had received many honours and awards for his work, including the Queen's Service Medal for public service in 2005.
The Old Blue, awarded annually by New Zealand's largest independent conservation organisation to people who have made significant contributions to Forest & Bird or to the organisation's conservation goals, commemorates the last breeding female black robin, which, thanks to work led by pioneering conservationist Don Merton, saved her species from extinction in the 1980s.