There are about 400 calories per 100g of dried sprats.
I find it very useful to understand how many calories my dog needs per day so that I can figure out how to combine foods and treats to still give him the right amount of energy.
There is plenty of help online on how to calculate it but if you have the weight, age, neutered status and exercise levels for your dog I can help.
As a guide, my 23kg young, intact, male springer needs about 1400 calories per day so 100g of sprat would be almost a 3rd of his allowance.
Your cocker is likely smaller, may be neutered, may be younger and may not be out and about as much as mine (about 2 hours a day) so could be considerably less. Easily half as much for an average weight cocker who is adult, neutered and walks for about an hour a day - so 700 calories a day.
However, all dogs are individuals so even within similar dogs there is variation. If your dog eats all this and maintains or gains weight then something needs to be cut back and the sprats might be one.