People with more than one fisherman may find this useful when this daily appears.
I send my first char out to do the quest normally. Before coming back kill another mammoth/rhino to get the debuff again. Once back in Dal, go to a quiet spot in the Underbelly (under the inn, maybe) and jump in the water. This creates a pool. Log in with second character, get the quest, fish that pool in Dalaran and turn quest in without having to fly to Borean Tundra.
It requires some timing - neither the debuff nor the pool last that long. I tend to pick up the quests first, position the second character and then log straight in and fish after creating the pool.
My apologies if this has already been posted elsewhere - I did a search and couldn't find anything.