The other professions have improvements for loot. I propose a skill line for fishing ending with three active skills of which you can only choose one. 1: use of a net 2: use of traps 3. Use of a harpoon for large sea catches more roe with slightly better chance to get perfect roe.
Passives to improve catches.
An option to catch more rare fish or to receive more resources from crab and a giant clam