Final answer:
Non-fishing communities recognized the cultural importance and interdependence with fishermen's livelihoods, leading to support for customary fishing territories.
Step-by-step explanation:
Non-fishing communities around the lake supported the fishermen's attempts to protect their system of customary fishing territories for several reasons, including the recognition of the cultural importance of customary systems and the interdependent relationship between fishing and other economic activities. Tradition and history have shown that fishing practices are not only about sustenance but also about maintaining livelihood security and rights historically acknowledged in treaties. Furthermore, supporting the rights of fishermen can also indirectly benefit non-fishing communities economically through trade and resource exchange.