More than 200 seal pups have died in the Scottish Borders after the east coast was battered by wind during Storm Arwen.
Staff there found 224 pups in the water, with "many more" washing up ashore.
They have plans to carry out a survey on animal numbers later this week but they are not confident about numbers.
A spokesman said: "Having worked on seal colonies for 10 years I have never seen a storm cause damage on anything like this scale before."
Trees have also come down on the reserve and staff have urged people to avoid the wooded side of its loch. Staff say they will have to undertake a "long clean-up operation".