As Kole S writes, "it's by design".
WarenZ, look at it this way : With your Level 27 status, you need 1.9M XP to reach the next level. A level 38 needs ... 15M !
How could he get 15M XP if the fishes that are offered to him by The Game were not bigger and more numerous than yours?
He struggles as much as you to progress, and he may even envy the levels 45
The mechanic behind this is described in my recent post about 1.25 the Golden Ratio in "Player Progression" section.
So that I can even tell you that a Level 38 has about 12 times more chances than you (i.e. 1.25 multiplied by 1.25 , and this 11 times, 11 being 38-27).
The gear, the skill points, the bonuses do not "explain" the big fishes, they are just "by-products" of the Progression. They make, explain, justify the "1.25".
Why does it look so unfair ? Because The Game wants to reward the progression, for players need rewards to continue taking pleasure in this wonderful game.
You also are already being rewarded (you have 12 times more chance than a level 16 ), but just not in these weekly rewards.
Solution : When I feel frustrated, I return to the jetty of Mosquito, fishing with the beginners, ... and I feel better .
If developers were considering improving the "fairness" of the reward allocation, they could easily put in place a handicap system, like in golf or tennis, to level all levels.
BTW, same applies to competitions...