People are starting to catch on that we are over fishing our waters. Some responsible markets and restaurants have stopped offering endangered fish, for the rest of us there is the Seafood Choices Alliance. They track species and what various organizations feel about them, and let you know if it is safe to eat the fish in their SeaSense database. Chilean Sea Bass for example might be delicious and trendy but the National Audubon Society, Monterey Bay Aquarium, and Environmental Defense recommend you avoid it. They even offer an alternative, and if the fish is ok to eat, recipes. A good resource to check before you head to the market.