It's definitely free. If you search "skin" on syns online the only ones that come up are:
Turkey skin, 25g roasted 6
Chicken skin, 25g roasted 6½
There's no mention of fish skin, and you are never, ever told to remove skin before cooking fish. Even battered fish is free if you remove the batter and leave the skin on:
Fish & Chip Shops, Cod in Batter,
batter removed, average large portion, 225g serving
Free
Im pretty sure the Yo Sushi one is just because its literally
fried ie in oil:
Check Our Restaurant Menu | YO! Sushi Restaurants & Takeaway
- Crispy
fried salmon skin. 114 kcal
- Crispy Salmon Skin Crispy
fried salmon skin with spring onion. 99 kcal.
There are loads and loads of other salmons listed that dont say anything like "skn removed" or "without skin" and are free.