To improve the quality of your fishing pole, hooks and the spindly taproot that you find increase your surivival. You can also use a higher quality tree for the pole and higher quality bone for the hook. The quality of spindly taproot is dependant on the quality of the soil, just like chantrelles and blueberries. If you find high q soil it is a good place to return periodically foraging. To improve the quality of your wood fish lure improve the quality of your axe and your carpentry skill, but the rock lobster and pine cone plug are also dependant on your survival skill.
Fishing does not cost stamina to use. You will replenish stamina at your normal rate.
It is not possible to fish on a shallow tile that is adjacent to shore. It must be at least one tile away from shore.
Survival does not affect the fish quality caught. Taken from
http://havenandhearth.wikia.com/wiki/Fishing