'BUCS, British Rowing and Rowing Ireland are providing support to her family during this difficult time and ask for their privacy to be respected.
'On behalf of everyone at BUCS, I wish to extend our condolences to the family and friends of Ailish and our thoughts are with them at this difficult time.'
A spokesman for the University of London Boat Club (ULBC), where Ailish was a member, added: 'We are devastated to learn of the death of Ailish Sheehan.
'Ailish was involved in a serious accident. The circumstances of the accident remain unclear and are likely to do so for some time to come.'
Club chief coach Phil Gray said 'The whole club is devastated by this news.
'Not only was Ailish a top oarswoman with a significant future in the international side of the sport but she also lit up the club with her humour and laughter.
'She was a great example to younger members and starting next year without her is hard to imagine at the moment especially as she had been elected vice captain.
'But our main thoughts are with Ailish's family who obviously meant so much to her.'
Ailish joined ULBC at the start of the 2015/16 academic year, arriving from Notre Dame University in the United States where she had been a member of their first Varsity eight.
During the year she won a gold medal at the British Universities Championship in the women's coxed 4, Senior fours at the prestigious Henley women's regatta and a bronze medal at the recent FISU World University Championships.
Lee Boucher, the team British team manager in Poznan, said: 'It is with great sadness that I have to report that our teammate Ailish has passed away in hospital in Poznan surrounded by her family.
'Our thoughts at this time are with all of her family and friends.'
He added: 'Like her performances on the water, Ailish gave everything right until the very end but unfortunately she was unable to win this battle.
'Ailish's family take comfort in knowing that she didn't suffer and that she was happy in her final moments.'
