Trident Item Texture not showing up

Basically, i have a resourcepack turning tridents into spears. The trident "entity" works fine, but the item in inventory displays as the normal trident texture, even though I changed the texture in the "textures/item" file. I tested it out with another resourcepack (I will provide link) and it doesnt work there either. Please help.

PS: the attached resourcepack isn't made by me.