Caleb needs to get a specific salmon. You can not pick the spot where you catch it. He will tell you where to find it. Listen to his instructions carefully. You will need to go to a lake in Seers village. There you need to catch a salmon. If you catch any other salmon you will not be able to give it to him. All the other fish can be caught wherever you want. So you do not need to worry about that.  The same goes for Avan and gold jewelry. He does not accept any jewelry besides the perfect jewelry. So you can not use regular gold ores to smelt jewelry for him.