Wainwright has been a leading figure for Dragons since making his debut in 2017, which was followed by a rapid rise to the international stage.
The back-row forward has won 62 caps, featured in all five matches of the 2019 Grand Slam and has played at two World Cups.
“He is going to be a massive loss,” said Tiatia. “I love Waino – he is a unique man and a heck of a player who brings confidence to the group.
“He trains hard, does all of the one per centers really well and is a really good pro; people can influence others and he is definitely a person we will miss.
“We know that he will give his best until the season is finished and that is exciting because there are a lot of things that we can do as a group together and objectives that we want to achieve, with Waino as part of that.”
Tiatia is working with Dragons head of recruitment Jonathan Westwood to fill the void, with Wainwright’s decision leaving plenty of room in the budget.
The Rodney Parade club, who signed a new Professional Rugby Agreement with the Welsh Rugby Union in May, will have an increased playing budget of approximately £6m next season.
“We are looking at the moment at opportunities for someone to come in and complement what we are doing here and really impose themselves,” said Tiatia.
“We have got a bit of work to do to find the right person, or persons. Retention is really important and so is our recruitment.”
