Migration ecology of marine fishes, by David Hallock Secor

Many species of marine fishes migrate for reasons such as reproduction, seeking food, passive dispersal as larvae, or due to climate and ocean forcing. Since they are able to respond sensitively to environmental conditions, their migratory patterns are mainly related to oceanographic factors and to currents.

Since many fish species are very important fisheries resources and ecosystem components, the science of fish biology and ecology around the world has grown rapidly. Recent advances in fisheries and aquatic science have enhanced interest in the migration and movement ecology of fishes for a better understanding of processes and mechanisms, with the aim of supporting fisheries management and conservation purposes. As a result, remarkable articles and some interesting books have been published on fish ecology and migration, but most of the recent books are either on specific species (e.g. Quinn 2005; Ganias 2014) or for specific regions (e.g. Allen & Horn 2006; Humphries & Walker 2013), or for freshwater ecosystems with an emphasis on diadromous fishes (e.g. Lucas & Baras 2001; Khodorevskaya et al. 2009; Ueda & Tsukamoto 2013). Therefore, the need for a comprehensive and up-to-date innovative book which covers a broad range of aspects related to the migration and movement ecology of marine fishes has been considerable. David Hallock Secor has identified this void and filled it with his excellent synthesis book Migration Ecology of Marine Fishes.

This book presents findings from a more than 40 year-long, cutting-edge research effort as well as an up-to-date synthesis of the current state of knowledge based on a variety of state-of-the-art digital technologies (e.g. microchemistry, telecommunications) and methodologies (e.g. stable isotope analysis). According to Secor, the volume was inspired not only by Fish Migration (Harden Jones 1968), which described pioneering and general concepts on fish migration, but also by the recent period of enhanced scientific exploration and discovery. Indeed, with the publication of Harden Jones' book, our knowledge of fish migration has dramatically increased. Secor's book comprises theoretical, quantitative analyses and reviews original research articles, some of which are authored by himself and his own students, laboratory members and collaborators.

The scope of the present book is vast and it consists of seven chapters that cover a broad spectrum of themes on the hidden lives of marine fishes, movement ecology (fishes and birds), mating systems and larval dispersal, complex life and marine food webs, population structure, propagating propensities, and resilience. The text is complemented with detailed tables, graphs, diagrams, photographs, and maps throughout the chapters, presenting conceptual schemes and data. However, some of the photographs are not of the highest print quality (e.g. Figure 3.1, Figure 3.4). A significant strength and striking feature of the book lies in the summary sections included at the end of each chapter, which present at a glance critical information and vivid reviews for the reader. Furthermore, the book includes an extensive and up-to-date bibliography covering the subject as well as providing readers with the best sources from the preliminary literature. In terms of the purpose of this book, the author hopes that it will contribute and stimulate ‘ … to examine how migration and life cycles of fishes confer production, stability, and resilience to populations, metapopulations, and species'. Then he also adds, ‘Of particular interest in this book are the latencies, carryover effects, nonlinear feedbacks, overheads, and redundancies that influence how migration and life cycles respond to ecosystem change.’ In my view, he has been successful in achieving these aims. The author also indicates current gaps in our knowledge when discussing the topics of the volume.

In the first chapter, there is a review of historical concepts and a definition of fish migration; it also supplies a glossary of terms used to describe the migration ecology of marine fishes, and an appendix on traditional migration classifications (p. 22), as well as an overview of factors influencing migration. The influence of external factors (e.g. food web, abiotic conditions) and internal states (e.g. size, energetic status), both at the individual and population levels, is illustrated with clear examples and diagrams. Phenotype plasticity, and life-history, ecological and genetic constraints in migration ecology are also considered. Chapter 2 interestingly compares movement ecology between birds, fishes and other taxa that present a wide similarity in locomotion in fluid environments (water or air), seasonal migrations, mating systems and navigation. Commonality in how birds and fishes pursue behavioural rules (e.g. aggregation resulting in self-organising behaviour in schools and flocks) and parallel developments in measuring and analysing individual movements are outlined. Chapter 3 focuses on mating systems and complex mating behaviours in marine fishes, including examples, e.g. shelf-spawning Atlantic cod, ocean-spawning Japanese eel, upwelling-spawning rockfish, and estuarine-spawning striped bass. Next, it investigates the effects of a targeted harvest of spawners on mating systems, larval dispersal and population sustainability.

Chapter 4 compares marine and terrestrial food webs, with emphasis on production and biomass structure among trophic levels, highlighting size-related life-history and habitat relationships and the exploitation of transient and patchy prey resources. Life-history modes in teleost fishes (periodic and opportunistic strategies) and elasmobranchs are reviewed and fish schooling is discussed as a strategy to match food web dynamics. Chapter 5 covers in detail the recent discoveries in natal homing and related hypotheses and theoretical considerations.

In Chapter 6, the author uses many examples to illustrate types of partial migration (a ubiquitous feature in marine fishes), including non-natal and natal divergences, differential migration, skipped spawning, straying, irruptive migration and vertical migration. Specific examples are elaborated featuring Arctic char, sticklebacks, Atlantic herring, Japanese eel and Atlantic cod. Finally, Chapter 7 provides a unique overview of resilience (stable state) theory, regime shifts, diversity in age and spatial structure, and on how climate oscillations (such as El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO)), exploitation and other forcing variables influence population states. I would like to highlight the sentence which has most caught my attention in this chapter: ‘In general, exploitation can make populations more sensitive to climate variability owing to changes in abundance, age structure, loss of spatial structure, alteration in life history traits, and changes in food web structure.’

To sum up, Migration Ecology of Marine Fishes, in addition to introducing pioneering concepts on fish migration, presents timely, highly innovative research results together with case studies and useful examples in a well-organized manner. As far as I am concerned, it is now the first comprehensive reference on the subject. It will be very useful as a textbook for postgraduate as well as advanced undergraduate courses in fish and fisheries ecology and various related subjects. However, as a further aid to undergraduate students the author could have provided some colour diagrams to illustrate migrations, behaviours, mating systems and life cycles of marine fishes. Although this is not a field guide, photographs would have boosted the attractiveness of the book for readers. I would have liked to see at least some interesting colour photographs at the end of the volume.

Last but not least, this is undoubtedly an outstanding book and I strongly recommend it to all scientists, researchers and students who are interested in migration and fisheries ecology. I cannot praise it highly enough.