I spotted a Magpie taking a taste of the pond near the frog spawn so I fashioned a square of chicken wire and weighed it down with stones on one side to sit above the water but make it difficult for Mr Magpie or any other potential predators getting hold of them... of course when they roam free as tadpoles they will have to fend for themselves among our 70 odd fish!
Newts eat frog spawn Tetley, but they are not entirely responsible for the decline of frogs at a pond.
As a pond matures the number of invertebrate predators increases. This means less surviving tadpoles and less adult frogs returning in following years to lay spawn. At the same time newt numbers increase.
One finally gets to a stage where only a little spawn is laid and the newts scoff the lot and there are only newts left.
In a garden we can intervene by growing on the spawn in nursery ponds or in trays of water until the tadpoles are large enough to avoid the newts.
In the wild, if at all possible, dig a new pond.