Being he was in the fog in the pic that makes the antlers always look a lot darker on a wet or damp dark day. Google antler stain(ing) and you will find a lot things to buy or try.
I had other pics of him in better lighting and they are dark. But I understand what you are saying. I did Google it, made my head spin with all the techniques and opinions.
I have used paste shoe polish. It works.
Got any pics? What color?