Fish have evolved a remarkable variety of reproductive modes and behaviours that reflect their ecological and taxonomic diversity, and their ability to adapt to a wide range of environmental conditions. The physiological, endocrinological and molecular mechanisms that underpin sexual development, and the complex behaviours that facilitate mate choice and sexual compatibility, are all potentially sensitive to changing environmental conditions. This theme will explore this diversity and focus on how changing environmental conditions impact fish reproduction, from sex determination and sexual development through to parental care.

Fish adopt a wide range of feeding and foraging strategies and have evolved an astonishing array of trophic specialisations to exploit available food resources, with these adaptations often forming the basis for species proliferation and diversification. This theme will focus on this diversity and will seek to develop understanding of how environmental change is impacting the trophic interactions of fish in aquatic environments around the globe.

Fish are studied by behavioural researchers from a wide range of perspectives; as models in molecular genetic, neurobiological, physiological and toxicological experiments and as subjects in behavioural and evolutionary ecological field studies. Increasingly, the results of these studies are being integrated across systems. It is increasingly clear that the behaviours of fish, which have evolved as adaptations to life in myriad complex environments, can be highly sensitive to environmental change. The focus of this theme is to explore our current knowledge of fish behaviours, how they are impacted in changing environments, and our understanding of the broader ecological implications of such changes.

he impacts of changing environments have far-reaching implications for the physiology, behaviour, abundance and distribution of fish, and for their interactions with other species. As a consequence, the biology and ecology of fish populations – as well as the broader communities and ecosystems that fish live in – are often impacted under changing conditions. This theme will focus on developing a greater understanding of how global change is impacting fish populations with implications for aquatic communities, as well as for fisheries and fishing communities that rely on them.

Fish often show remarkable levels of within-generation plasticity in morphology, behaviour and physiology, typically as an adaptation to occupying environments that are naturally subject to environmental fluctuations. In a rapidly changing world, it is possible that this intrinsic ability of some fish to respond plastically to environmental change gives them an advantage. This theme will focus on exploring the role of plasticity in fish ecology and developing a greater understanding of the potential role of plasticity in adaptation to environments that are subject to directional change.

As the impacts of global anthropogenic change are becoming better understood, there is an increasing drive and motivation to identify conservation priorities and to make practical changes that will mediate some of the most damaging impacts and improve the situation for fish and fisheries. This theme will focus on showcasing current studies in fish conservation and on developing approaches to improve, replace or restore the habitats, environments and ecosystems that fish live in.

The introduction or invasion of novel fish species, fish predators, fish parasites or species that otherwise compete directly or indirectly with native fish present an increasing challenge for fish populations and aquatic ecosystems around the globe. This theme will focus on our current understanding of species introductions and invasion ecology, and showcase recent studies that have developed our understanding of these increasing threats to aquatic biodiversity, fish and fisheries.

Recent advances in the recording and analysis of underwater sound have generated a surge of research activity that is rapidly developing our appreciation and understanding of the critical role of acoustic communication in the biology and ecology of fish. This theme will examine how fish utilise sound in their behaviour and ecology, how anthropogenic changes to underwater soundscapes impact the efficacy of acoustic communication, and how this improved understanding might be used as a tool to benefit the restoration of fish habitats.