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Apart from the introduction (Chapter 1) and synthesis (Chapter 13) sections, there are 12 chapters that cover the full range of topics pertaining to fish and fisheries in estuaries:

 Chapter 2 (Whitfield et al. 2022a) deals with the zoogeography of estuary‐associated fish species, as well as the influence of estuarine typology on the composition of fish assemblages. Included in this chapter is an examination of the nature of three fish functional groups, namely estuarine use, feeding and reproductive modes, and how these groups drive fish assemblage structure and guilds within estuaries.

 Chapter 3 (Houde et al. 2022) covers the reproduction and recruitment of estuary‐associated species, with an emphasis on the ecology and dynamics of early‐life stages, including eggs, larvae and juveniles, and how estuaries support these functions. The nature of estuarine and marine spawning grounds and their use by different kinds of estuary‐associated fish species is examined and the recruitment processes from these spawning grounds to specific estuarine nursery areas described. In addition, the factors driving fish recruitment, growth, productivity and its variability are discussed, with particular emphasis on both physical (hydrodynamic) and biological factors governing egg and larval mortality. Knowledge of these processes may assist in predicting recruitment variability and identifying threats to both reproduction and recruitment.

 Chapter 4 (Able et al. 2022) provides a focus on habitat use by fishes in estuaries. Apart from elucidating the characteristics of different habitat types, the role of habitat mosaics and connectivity between different habitat types for fishes is also examined. Much of the chapter is devoted to the dynamics of habitat use by fishes. Settlement processes in estuarine nursery habitats are covered, as are the seasonal, tidal and diel cycles governing habitat use. Site fidelity and fish movements between habitats are highlighted, with the role of episodic events in driving or preventing habitat utilization also being documented.

 Chapter 5 (Whitfield et al. 2022b) deals with the food and feeding ecology of fishes in estuaries. Following an assessment of fish foraging behaviour and various aspects of food intake (e.g. prey detection and feeding periodicity), the environmental and biological factors influencing the foraging of fishes is assessed. Trophic categorization of fish species in estuaries is dealt with in some detail, as is competition, resource partitioning and energy flow through the fish community. Included in this chapter is a summary assessment of the predators of fishes in estuaries and how both natural and artificial perturbations may influence food webs within these systems.

 Chapter 6 (Cabral et al. 2022) begins with an examination of the concepts and definitions relating to estuarine environmental health. This is followed by a review of natural and anthropogenic pressures impacting on estuarine fish assemblages and how fishes can be used as indicators to assess estuarine health. The response of fishes to human pressures is also covered, as well as disentangling fish responses in a multi‐stress context arising from global changes. The chapter concludes with some suggestions for future directions of research within this field.

 Chapter 7 (Gillanders et al. 2022) deals with climate change within estuaries and the impact these changes are having, or may have, on associated fish assemblages. Actual or potential impacts on fish and fisheries are assessed at the individual, population and community levels, with particular emphasis on physico‐chemical changes brought about by changes in sea level, estuary mouth morphometrics, water temperature, salinity and dissolved oxygen attributes. Case studies showing the influence of climate change on estuary‐associated fish assemblages are addressed, and the possible effects of climate change on coastal fisheries and the socio‐economics of coastal settlements is also covered. Gaps in our knowledge on the above topics are emphasized and future research directions suggested.

 Chapter 8 (Lepage et al. 2022) covers the topic of estuarine degradation and restoration during a period of major global change. The objectives of habitat restoration, rehabilitation and creation are described, as well as at what taxonomic level the restoration of ecological processes need to be addressed. The main sources and form that estuarine degradation normally takes are explored, as well as the array of tools available to better understand the estuarine processes so as to achieve restoration success. Both successful and unsuccessful attempts at rehabilitation are examined, in addition to the tools that can be used to assess the success or failure of such restoration projects.

 Chapter 9 (Blaber et al. 2022) reviews fisheries yields for estuary‐associated fishes around the world. Tropical, subtropical and temperate systems are covered on different continents, with the problems and issues pertaining to estuarine fisheries receiving particular attention. Fish production by some of the main species, including marine, estuarine and diadromous taxa are dealt with in some detail, and the way forward in terms of sustainable fishery yields is also addressed. In addition, the management of estuary‐associated fish stocks both within estuaries and in the marine environment is also covered. Case studies in all the above sections serve to bring practical management examples to the table. The chapter concludes with a summary of the measures for successful management, gaps in our knowledge relating to management and recommendations to fill these gaps.

 Chapter 10 (Cowley et al. 2022) assesses the conservation status of estuarine fish on a global basis. Particular attention is given to threatened species and extinction risk, as well as an analysis of the threats to the conservation of fishes in estuaries, including fisheries impacts, habitat loss, freshwater input reduction, water pollution, introduced species and climate change. Various conservation efforts are also reviewed, including harvest control measures, the role of protected areas, rehabilitation and habitat restoration and improved catchment management. The chapter concludes with an examination of current and future challenges for the conservation of fishes in estuaries.

 Chapter 11 (Moyle & Stompe 2022) provides an overview of our current knowledge of non‐native species in estuaries. Issues that are addressed include the global distribution, characteristics, taxonomy, importance and management options for non‐native species in estuaries. The importance of non‐native fishes from selected case studies around the world are covered in some detail, as well as the conditions that favour the establishment of these taxa in estuaries. Biological interactions between native and non‐native species are reviewed, and their role in the development of ‘novel ecosystems’ in modern estuaries is also discussed.

 Chapter 12 (Elliott et al. 2022a) provides a focus on management issues pertaining to estuaries and how these issues may influence fish populations within these systems. After introducing management aims, objectives, frameworks and standards, the chapter then deals with management at the catchment, estuary and habitat levels.

 Chapter 13 (Elliott et al. 2022b) provides a synthesis based on all chapters in the book, as well as highlighting research that is required for the future. There is an emphasis that most research and knowledge on estuaries, their fish, habitats and fisheries need to describe and explain the nature of these changing systems, the natural and anthropogenic causes of that change, and the management of these systems for the benefit of both the natural and human components.

In addition to the above chapters, there are two appendices that focus on the gear and methods involved in studying fish in estuaries:

 Appendix 1 (Franco et al. 2022) describes field methods for fish monitoring in estuaries, including fishing techniques (nets and traps), acoustic and visual detection and DNA‐based sampling methods. The features, advantages and disadvantages of each technique (e.g. applicability, selectivity, efficiency and standardisation for recording different aspects of fish ecology) are presented using best practice examples from study cases worldwide. The contextualisation of monitoring strategies for fishes in estuaries, including legislative constraints and requirements, are also covered.

 Appendix 2 (Elliott et al. 2022c) focuses on the data analysis and interpretation required to study fish in estuaries. The analytical approaches (variables and parameters, analytical tools and interpretation) are described according to the level of biological organisation (e.g. individual, population, community) and their fit for purpose, taking into consideration the aim of the monitoring study (e.g. temporal variability, impact assessment, characterisation). Case studies are used as best practice examples to illustrate the above processes.