Soft cover, pp. xx + 275, acid-free paper, I figure, 10 maps, 8 text drawings and 8 colour plates "The credibility and success of conservation and management programs depend on the depth of knowledge of the subject matter" This is the text of a sermon on the desirability of preservation of trout diversity which forms the epilogue to Robert Behnke's impressive descriptive catalogue of the Native Trout of Western North America. The crusading style and authoritarian flavour of the rallying call to the over-cautious represented by this Epilogue is foreshadowed throughout the previous thirteen chapters. If you've lasted the course, you are well prepared for the final chapter, and it's good stuff! This final tract is targeted at fishery biologists, managers and administrators, to act now, on all the information available to ensure the maintenance of existing trout diversity, and not to delay until quite sure that evidence for adaptive variation is absolutely, irrefutably respectable scientifically. Patience has become a luxury, and a heavy premium is placed on the judgement of the experienced biologist. Many biologists will applaud this, and many administrators will worry about how to quantify that judgement.
The necessary depth of knowledge of cutthroat, rainbow, gila, apache, Mexican golden and the other Mexican trouts is displayed to the reader in grand, but disciplined and economic style -just occasionally perhaps a little too ex cathedra for my taste. The book is organized into four main parts. The three introductory chapters of Part I cover Classification, Origins & Distributious, and Biology. This part is really a summary of the book, and almost needs to be read both before and after Parts n-iv. Part II leads off with a general introduction to cutthroat trout, followed by four chapters dealing in turn with each of the four main groupings of this species in a standard format of typical characteristics, description, distribution, taxonomy, life history and ecology, and present status. Part IH repeats the pattern for the three groups of rainbow trout, and Part Iv is a single chapter for the rarer south-western species.
Organizing the immense amount of disparate data on these trout species into a tractable scheme is a staggeringly successful tour de force. The meat of this book lies in the discussion of origins and distributions, because the classification into intraspecific groups depends entirely on interpretations of relatively recent geological history, and how these species have responded to major environmental change. The author starts from the assumption that the present trout fauna arose from a common ancestor of cutthroat and rainbow trout some 1-2 million years ago, and that further radiation has occurred at nottoo-definable times into several different forms of these two main species, with the rainbow line giving rise to the gila, apache and Mexican golden trouts. The precedence of cutthroat over the other species as the occupant of western North America is deduced from present distribution, from morphology and from genetic data. But that present distribution of species and of separate groupings within species is discussed in great detail with reference to glacial history, and particularly to climatic changes affecting the levels of lakes and rivers, and consequently changing the patterns of drainages over the past 70,000 years. The presence of native populations in Atlantic drainages would be difficult to comprehend without the geological information on watershed capture, as would the origin and variety of the trouts adapted to high temperatures or to high alkalinities in the