Our first visit, we were a little early to see any Seal pups. 2 had been born, but were not visible from the viewing area. Last year 2,134 were born: https://www.lincstrust.org.uk/get-involved/top-reserves/donna-nook/weekly-update
We were a bit early to see the pups. According to the BBC, a lot more have been born and some are now visible from the viewing area: https://www.bbc.co.uk/news/uk-england-lincolnshire-63534717