That's outstanding! It's always possible to do better, but yes, that's a very good score. Better than I've done myself without cheating.
And speaking of cheats, yes there are some. They involve pressing multiple keys at once, and they seem to work on some computers/keyboards but possibly not on others. If you ever use a cheat while playing, your final score won't be eligible for the top scores list, and you won't get a code to prove you scored what you did.
If you don't want to know what cheats are available, stop reading now! Otherwise, scroll down.
While fishing, hold down "c", "h" (for "CHeat") and these keys:
f for fast time (you'll get cold quicker too!)
f and right shift for super fast time (mostly just uses up your fishing time in a few seconds)
s for slow motion
o to trigger an offer (somebody will come up and offer a trade, etc)
t to trigger a conversation (two people will walk by while talking)
While you click "New Game" from the menu, hold down c, h and m (for money) to start with $1,000.