What is the benefit of leveling up Fishing Proficiency?

[Tigershark]

As asked in the title: What is the benefit of leveling up your Fishing Proficiency?

Does it speed up how quickly you reel in fish? 
Increase higher rarity chance?
Increase the size of your reeling bar?
Increase the range you can throw your hook?
Increase the speed in which you find new fish after throwing out your hook?
Does it unlock new fish to be found?

What's the benefit? Is there even one yet, or is it too early in the development and it's just a test for the proficiency system as a whole?
On top of that, what is the cap and what's the point of the Shuriken next to the level? Are they it's rank?

[Demon of the Leaf]

i dont think there is a benefit