In answer to your question, NO, fishermen aren't all catching and killing fish. Most fisherman practice catch-and-release. The fish is caught and returned to the water unharmed. Prosec has written and spoke on the topic at length. True - some are killed and eaten by fly-fishers and other angler, but not the majority. Everyone on the planet is "killing and eating part of nature" be it animal or plant life.
More information about text formats