Cambridge rowers have been accused of killing ducklings during the annual race known as the May Bumps.
Lee Culley, 44, who lives on a houseboat in the River Cam, described being horrified at the sight of the female team's rowing blades striking a brood of ducks, killing at least two.
He said: “It was absolutely disgusting. They just sped through even though I shouted to them, warning them about the ducks.
“They just kept on going and their blades went through the ducks and killed two. The ducks were only three weeks old. Another one died the next day and the mother has none but keeps coming back to my boat looking for the brood."
The May Bumps are a set of rowing races held annually on the River Cam. They began in 1887 and take their name from their distinctive format: if a boat bumps into the rear of a competitor, the boat in the fore must pull over and let them pass.
Last year, animal rights campaigners dressed as swans were arrested after bringing the May Bumps to a halt.
A spokesman for the Cambridge University Combined Boat Clubs, which runs the Bumps, said: “Every effort is being made to mitigate disturbance to wildlife and to keep ducks and other waterfowl out of the way of racing boats.
"Indeed, the start of the men’s second division on Wednesday night was delayed by 15 minutes while a family of ducks were guided out of harm’s way."