so you want the hook to deal damage?
You can do that, but it only damages when you pull the player;
first, place a Player Fish Event. Now we need to check if the player pulls an entity, to do that place an If Variable [game value: Fish Event Cause] = [text: pull_entity]. We detect if the player pulls an entity but it will work at all entities and not just players, to detect if it's a player place an If Variable [game value:Entity Type] = [text: player] and make sure to shift-right click the game value and make it's target Victim, now inside the brackets just place a Damage Player and shift-right click it and make it's target Victim, inside the Damage Player chest put a number of your choice for the damage