Preface

Fish and fisheries play a significant role in ecosystems around the world. Seafood is a source of healthy dietary protein and the seafood industry brings in more than a trillion dollars annually and employs millions of people. Fish stocks are a key component of the global food system and a vital part of the aquatic environment and food chain. According to the Organization for Economic Co-operation and Development (OECD), the ocean's economic output is \$1.5 trillion annually; this number is expected to increase to \$3 trillion by 2030. The international trade value of fish is approximately \$40 billion per year. Fisheries raise and harvest fish and other aquatic life and are sites for fishing activities. Commercial fisheries include wild fisheries and fish farms, both in freshwater areas (about 10% of all catch) and the oceans (about 90% of all catch). About 500 million people worldwide are economically dependent on fisheries. In 2016, 171 million tons of fish were produced; however, overfishing is an increasing problem causing declines in some populations.

Healthy oceans are not only a source of jobs and food but are also important for economic growth, climate regulation, and the interests of coastal communities. Proper knowledge of the life, habits, and behavior of fish is essential to plan, control, and manage fishery resources. Monitoring and analyzing fish diversity, abundance, and catch, as well as target and non-target fishing, types of capture methods, and fishing fleet, provides information about the biological sustainability of commercial fishing. Catch data measured in stock assessments is helpful to determine sustainable fishing.

Fish and fisheries play critical roles in ocean health, community well-being, food security, and economic stability. Ensuring their sustainability is a key goal of governments, civil society, philanthropies, and development institutions. Collectively, this work covers a wide variety of types of fisheries, affected species, habitats, ecosystems, jurisdictional and policy contexts, management capabilities, and socioeconomic conditions. The application of scientific knowledge for the development of the fishing industry lies in an intimate knowledge of the biology of fish.

Fisheries science plays a crucial role in understanding and managing aquatic ecosystems and the resources they provide. Fishery scientists study aquatic ecosystems, including the physical and chemical environment, and the interactions between species and their habitats. This helps to provide a comprehensive understanding of these systems and their ecological processes.

This book summarizes different directional studies on fishery biology and sciences. It highlights the role of fisheries in the biological and management sciences through the use and application of various traditional and advanced biological approaches. It is organized into two sections. Section 1, *Traditional (Morphological and Ecological) Approaches*, discusses some traditional approaches and focuses on the relevance and

importance of morphology, ecology, and biological studies. Section 2, *Advanced (Cellular and Molecular) Approaches* focuses on the importance of advanced cellular and molecular studies in the fishery sciences.

The taxonomy or identification of species is the way in which living organisms are named, described, and classified based on multiple approaches ranging from morphological descriptive characters to higher molecular levels. Using morphological observations, taxonomists identify, describe, and arrange the species into families, classes, phylum, and other divisions. Chapter 1, "Perspective Chapter: Crustaceans Taxonomy", discusses crustacean (crab, shrimp, lobster, and crayfish) taxonomy and classification, as this diverse and important group of fish, has economic implications worldwide.

There is an intimate relationship and interaction between the aquatic ecosystems, including the physical and chemical environments, species, and their habitats. This not only helps to provide a comprehensive understanding of these systems and their ecological processes but also reveals the impact of environmental conditions and quality on the overall biodiversity of the aquatic body as well as species morphology, biology, and other related traits. Chapter 2, "Eco-Morphology of Some Decapod Crustaceans in a Tropical Coastal Marine Waters", highlights this relationship between the morphology, population structure, and dynamics of crustaceans and the water quality of the coastal areas of Ohio Nigeria.

The study of fish populations and their habitats emphasizes the sustainability of biodiversity on the coasts as well as determines sustainable fishing levels. The knowledge of the physical and chemical factors (tides, seasonal variations, dissolved oxygen, nutrients) important for fish presence and survival as well as for their spatial and temporal distributional pattern, natural history, and ecology of organisms affecting the particular fishery play a crucial role in understanding and managing aquatic ecosystems and the resources they provide. Chapter 3, "Biological Characteristics of Some Fish Species in the Mekong Delta, Vietnam", provides information about the variety of freshwater and brackish water fish in the Mekong Delta river system. The chapter discloses the fish population structure, distribution, species composition, and their roles in the environment of Vietnam waters. In addition, it examines the growth patterns of some commercial fish and their fishing status.

The provision and availability of food are important for the presence, existence, and growth of fish species. Chapter 4, "Feeding Diversity of Finfish in Different Wild Habitat", reveals the distribution pattern of finfish through grouping (tidal visitors, permanent residents, partial residents, and seasonal visitors) and its relationship with food and feeding behavior. The chapter describes the mode of feeding in most fish families and discusses the various tools and techniques of analytical research for feeding ecology.

Achieving sustainability in fisheries is a focus of fishery biologists and scientists. Anthropogenic, environmental, and climatic changes have drastic impacts on aquatic bodies. As a result, water bodies face challenges such as changes in ecosystems, species habitats, distribution, and dispersion. Fishery biologists use both traditional and advanced tools to guide management and conservation efforts, ensuring that

**V**

human brain.

and Filip Lovricevic.

fish populations remain sustainable, healthy, and productive. Chapter 5, "Sustainable Management Plans in Fisheries and Genetic Tools: An Overview of the Challenge in Invertebrates' Fisheries at the Central Area of the Southern Bay of Biscay, Spain," provides an overview of the challenges faced by invertebrate fisheries in the southern Bay of Biscay, Spain. It also examines the use of genetic markers as important tools for understanding the ecological and genetic status of commercial species as well as the

The latest developments in fish biology research include fish nutrition, ecology, reproduction, fish development, fish immunology, biomedics, and fish welfare. This information is helpful for species adaptability, sustainability, and restoration and conservation management. Chapter 6, "Plasma and Hemocyanin Phenoloxidase Derived from the Hemolymph of Giant Freshwater Prawn *Macrobrachium rosenbergii* (De Man, 1879)" highlights the importance of hemocyanin in triggering innate immunity through one of its subunits that functions as the active moiety. It describes the biochemical composition and other molecular constituents of particular proteins to

Chapter 7, "Isolated Crayfish Stretch Receptor Neuron Electrophysiology May Explain a Longstanding Mystery of Human Brain Functioning: Eureka Moment", uses the example of crayfish to help resolve the mystery of human brain functioning. It focuses on the complex system of neuron functions by describing single-neuron physiology (Eureka moment), which can be helpful to understand the privileged function of the

I am indebted to many people who have contributed to the successful publication of this book. First, I would like to thank the authors for their excellent chapters. Their cooperation and patience are highly acknowledged. Second, I would like to thank the staff at IntechOpen, particularly Author Service Managers Sandra Maljavac, Andrea Tomurad, Sara Tikel, and Paula Gavran and Commissioning Editors Jelena Germuth

**Dr. Noor Us Saher**

University of Karachi, Karachi, Pakistan

Centre of Excellence in Marine Biology,

provide insight into the biochemical approaches in the fishery.

management and planning of fisheries.

fish populations remain sustainable, healthy, and productive. Chapter 5, "Sustainable Management Plans in Fisheries and Genetic Tools: An Overview of the Challenge in Invertebrates' Fisheries at the Central Area of the Southern Bay of Biscay, Spain," provides an overview of the challenges faced by invertebrate fisheries in the southern Bay of Biscay, Spain. It also examines the use of genetic markers as important tools for understanding the ecological and genetic status of commercial species as well as the management and planning of fisheries.

The latest developments in fish biology research include fish nutrition, ecology, reproduction, fish development, fish immunology, biomedics, and fish welfare. This information is helpful for species adaptability, sustainability, and restoration and conservation management. Chapter 6, "Plasma and Hemocyanin Phenoloxidase Derived from the Hemolymph of Giant Freshwater Prawn *Macrobrachium rosenbergii* (De Man, 1879)" highlights the importance of hemocyanin in triggering innate immunity through one of its subunits that functions as the active moiety. It describes the biochemical composition and other molecular constituents of particular proteins to provide insight into the biochemical approaches in the fishery.

Chapter 7, "Isolated Crayfish Stretch Receptor Neuron Electrophysiology May Explain a Longstanding Mystery of Human Brain Functioning: Eureka Moment", uses the example of crayfish to help resolve the mystery of human brain functioning. It focuses on the complex system of neuron functions by describing single-neuron physiology (Eureka moment), which can be helpful to understand the privileged function of the human brain.

I am indebted to many people who have contributed to the successful publication of this book. First, I would like to thank the authors for their excellent chapters. Their cooperation and patience are highly acknowledged. Second, I would like to thank the staff at IntechOpen, particularly Author Service Managers Sandra Maljavac, Andrea Tomurad, Sara Tikel, and Paula Gavran and Commissioning Editors Jelena Germuth and Filip Lovricevic.

> **Dr. Noor Us Saher** Centre of Excellence in Marine Biology, University of Karachi, Karachi, Pakistan

**1**

Section 1

Traditional (Morphological

and Ecological) Approaches

Section 1
