Natterjack toad eggs

Hi l'm new to this forum l just for the first time have found toad eggs in my pond, normally l get frogs spawn, this is probly a daft question, but is there anyway at this early stage to know if they could be Natterjack eggs? l've read they are more of a single chain is this right? some of mine look a bit like that, trying to keep the fish from them at the moment, seems to be working. Funny thing so far have no frogs spawn. Onice we at to get a toad out of the month of a large grass snake, managed to save both of them. All the best From Yazzy