Definitely easier to fish.
To loot it is pretty difficult, I've killed 221 Northern Pikes, and just 1 of them became a lootable Northern Pike. (Yes, this happens)
And I've completed all chakoyas bestiary and never looted any from them...
I used to make money fishing Pikes back in 2015, when 30k was still "a lot" of money. Now is almost nothing...
I did a route in which I could always be fishing, would almost never run out of icy holes. And my average was 5 Pikes/Hour, therefore, around 150k,
Here is my route:
PS: Going to point D is not always necessary, it depends a lot on your character fishing skill. If its low, then you will be fine by just fishing at A,B,C