FROM SEA TO SOURCE is the result of collaborations and partnerships with fisheries professionals all over the world, drawn together to provide a major new text on the theme of fish migration. The underlying concept is the increasingly recognised need for preservation but, more frequently, the restoration of free migration for all species of fish.

Migratory fish are well-known to us all, whether it's a meal of smoked salmon - now more available than ever - or a rare taste of caviar. Or perhaps it is the sight on TV of a grizzly bear as it waits patiently to catch a salmon as it leaps during its migration upstream? But for many millions of people worldwide the seasonal migrations of fish bring protein and are an essential food resource.

Migratory fish stocks are a vital component of river ecosystems. Their often complex life cycles place great demands on mankind as we seek to ensure the wellbeing of our fish stocks at a time of increasing pressure on rivers and the water cycle. Migratory fish are amongst the most demanding of fish, requiring free migration routes and often high standards of environmental quality, and as such they are potent indicators of the health of our environment.

Over the past millennium mankind has increasingly manipulated rivers to provide water for a range of uses including potable supply, agriculture, navigation, power generation, and cooling and, in so doing, has damaged their ecological connectivity and quality. This has led to the deterioration of most fish faunas, a global trend of rapidly declining stocks of migratory fish, and in some cases to the extinction of some species.

In Europe this has resulted in widespread environmental degradation, however in other parts of the world a later period of engineering of some of the largest river basins in the world has had a more profound impact. Here the construction of major dams has occurred more recently and in many cases, such as the Amazon and Mekong, is ongoing today at an increasingly rapid rate. The implications here are in many ways far more severe as they threaten the artisan life of subsistence fisheries on which tens of millions of people depend for their protein source.

Migratory fish must be able to move freely between the different habitats that sustain them. For the more iconic species such as salmon and eel this requires migrations from the open sea to spawning grounds in the upper reaches of rivers to complete their demanding life cycle. But all fish migrate, whether it is short-term movements for feeding or long distance migrations within the great rivers of the world for reproduction. And all fish are therefore vulnerable to the proliferation of barriers and obstacles. If fish are to survive and prosper, they must have free and safe passage between the habitats they use - from sea to source.

We have captured the important issues - societal and subsistence - in this book. We have brought together fish migration experts from every relevant continent, each of whom has direct practical experience of the issues and challenges. Their experience is represented in more than 40 examples illustrating the needs, and solutions for the preservation of fish migrations. The book gives an up-to-date overview of fish migration issues and technical solutions worldwide. It targets scientist, water managers and policymakers working in the field of fish migration, but also members of the general public with an interest in the well-being of our environment. The guidance and examples aim to inspire you to consider, address and prioritize fish migration solutions within a river basin perspective.

As we compiled the book we learned that familiar issues repeatedly arise in each continent. There has in the past been a central theme of inadequate understanding of fish and fisheries ecology, a naive presumption that whatever we do will have no damaging effect on river ecosystems, and an underlying prioritisation of economics above all other factors. Today in the 21st century the tide is changing in most parts of the world and the emphasis is increasingly on the restoration of river basin environments, often because of the significant ecosystem services that, after all, they provide.

The Water Framework Directive in Europe is a good example of river basin planning on a large scale. But elsewhere the proliferation of river commissions, ensuring the integrated management of the many cross-boundary rivers of the world, is strong evidence of more mature thinking and planning. The rivers of the world support many aspects of human lives, and it is of paramount importance that their well being, and the ecosystems they support and upon which many of us depend, may thrive. For most people, the wellbeing and productivity of fish populations is the best illustration of river health. This is why improved understanding of their migratory behaviours, the absence of which can result in extinction, is more important today than ever before. That is the tenet of this book, and we hope that it will contribute to the restoration of fish migratory pathways around the world.

FROM SEA TO SOURCE was launched at the International Ecohydraulics Symposium in Vienna in September 2012, and subsequently also at Sympass Fish Passage Conference in Brazil and the Living North Sea Event in the UK. Presentations in North America and Australia are currently being planned.

However, this is an ongoing project financed by an increasing number of sponsors, currently 35, from all over the world. They see the need for knowledge exchange and promotion of the fish migration theme worldwide. We will continue to present the guidance and to further our goal to protect and restore fish migration highways. We encourage you to share your knowledge at the ever growing World Fish migration Network and Fish Ecology Network on LinkedIn.