How does vegetarianism, in the context of not eating fish and other ocean-life, help preserve ocean ecology? What are the impacts of fishing on the ocean plants and trees (fauna)? How does this, in turn, impact the environment?
Here i can give you the answer depend on Hindu mythology why should we save there lives.
These are the lives which can't come out of the sea and hunt for the food in other words these big lives like shark and wheal can't came out of the sea so these are totally depend on the food inside the sea or water which is small fish. So we are not supposed to break there chain which starts from trees which are there inside the sea which is consumed by small fishes and then these fishes are eaten by the big fish.