For anyone interested in sorting out the oceans of conflicting information about sustainable seafood, "Four Fish: The Future of the Last Wild Food" by Paul Greenberg (Penguin, $25.95) is essential. This highly readable book addresses the undeniable fact that if humans continue to consume fish, we will have to come up with alternatives to catching them in the wild. Aquaculture - fish farming - is the obvious alternative, but as currently practiced, it tends to wreak havoc on its surrounding environs and uses up more edible resources than it produces.
The book is organized into four sections, each using a different species to illuminate a facet of the debate. (Greenberg reminds us that out of all the four-legged wild animals pre-agricultural man encountered, he chose to domesticate four - cows, sheep, goats and pigs.)
Salmon, once abundant in the wild, now ubiquitous in its farmed incarnation, is not, it turns out, an ideal candidate for farming. Sea bass, in the guise of branzino, has become the holy grail of aquaculture. Cod, once so numerous they named a Cape after it, is no longer plentiful enough to make all the world's fish sticks, spurring a search for a dependable, sustainable white-fleshed fish (think tilapia). Tuna, a marvel of strength and speed, forces us to confront the intersection of seafood and wildlife: Do we continue to fish the king of sushi into extinction? Or is it time to protect bluefin tunas like we do bald eagles and whales?