Is participation in a fishing tournament gambling?
Gambling is attempting to get something for nothing without rendering service or exchange of goods. Gambling is basically driven by covetousness, laziness, and recklessness. A gambler, desiring the possessions of another offers a risk that involves losing your possession on the chance of gaining what everyone else loses.
A fishing tournament is a competition for prizes based on the total weight of a given species of fish caught within a predetermined time. In this, people are comparing skills, much like wrestling or martial arts competitions. Often there is an entrance fee that covers the cost of holding the tournament, including the prizes being offered.
While there is an element of risk in both gambling and tournaments, risk alone doesn't make something to be a form of gambling. After all, there is a risk involved in starting a business or driving across town, but these are not what makes gambling wrong. It is profiting from everyone else's loss because you want what others possess that makes it wrong. Typically in a tournament, people are not after everyone's entrance fee but for the "bragging rights" to say they are better than most at a particular skill.