The book Four fish : the future of the last wild food by Paul Greenberg is a book about important and timely issues related to fish. The book focuses on Salmon, Sea Bass, Cod and Tuna. And while these four fish are the topic of the book it deals with some of the larger questions of fish, the oceans, ecology and general environmental concerns.
Historically there was the naive view of a nearly inexhaustible supply of these fish were available for the fishing fleets of the world but for several decades now that view has been known to be incorrect. This book deals with some of the cultural and economic issues which relate to the growth and demise of the fishing industry. Family and regional traditions of a fishing lifestyle do not exist any more in much of the North East Coast of the USA.
Salmon, Sea Bass, Cod and Tuna each have a section of the book that provides a history of the fish and its impact on those that fished it. Greenberg provides a very readable account of the impact of dams on fish populations and some of the issues arising from a reduction in biodiversity. The descriptions of meetings, interviews and personal experience provide a narrative structure which allows Greenberg to provide information without slowing down the flow of the book.
The discussion of fish farming is one of the better descriptions that I have seen in listing the pro and con for various activities as well as the some of the biological background and major hurdles for farming various species. One of the issues historically with fish farming has been that smaller fish needed to be ground up into fish food and this was not a sustainable practice. There are fish such as the Kahala renamed as Kona Kampachi which are being studied now as alternatives and in 2010 there was a pilot test project to raise these fish in large cages on food pellets without any wild fish meal. If successful this will provide a good candidate species for large scale farming.
In the text Greenberg briefly mentions several alternative fish species such the Pangasius in Vietnam, Barramandi from Australia and Tilapia. Tilapia is a fish which does not eat other fish and thus does not put a strain on other fish speces. It is a mild tasting fish and starting to show up in fish counters in the USA. Barramandi is not common yet in stores in the USA but is common in Australia and is very tasty if well prepared. When in Australia in 2010 one of the most delicious meals I had was a Barramandi dinner.
Greenberg suggests some principles for what fish should be domesticated for farming:
1. Efficient - high conversion of feed to edible fish
2. Nondestructive to a wild system. - Do not harm wild species or the environment
3. Limited in number - Only a few species because domestication can lead to unforeseen problems
4. Adaptable - Use species that can adapt to alternative feeds
5. Functional in a polyculture - Avoid monoculture and the mistakes of terrestrial agriculture
Greenberg urges us to have a set of clearly achievable goals for wild fish:
1. A profound reduction in fishing efforts
2. The conversion of significant portions of the ocean ecosystems to no-catch areas.
3. The global protection of unmanageable species
4. The protection of the bottom of the food chain
This book does not have all of the answers but it raises a lot of important questions and provides some pointers toward answers. In some instances there is only a brief mention of a topic that could easily be the subject of a long essay or a short book. For example Greenberg briefly mentions the role that governments have played in subsidizing fishing fleets. Subsidizing fish fleets breaks one of the feed back loops that might limit fishing activity due the costs making it unprofitable. I suspect this issue of government subsidizing of fishing fleets will be a difficult obstacle to overcome.