The best fishermen are those who are consistently able to land above-average catches of all the types of fish they intend to catch, whereas less successful ones will generally land below-average catches and accord any good catches to luck. As in most things, luck or lack of it may have a role in the level of success, but consistently successful or professional fishermen rely on much more than luck. They rely on a deeper knowledge of the behaviour of the fish they want to catch and where, when an d how they are most likely to catch them. Without this additional knowledge, the less successful fishermen are unlikely to improve their catches consistently and will thus be limited in their ability to increase their income to the benefit of themselves and their families.