Management and Handling of Commercial Crustaceans

Current crustacean production (~14 Mt) and value (up to USD60 billion) is significant and likely to increase further during the twenty-first century. Satisfactory management and handling of live crustaceans are important to safeguard the value, security, safety, and sustainability of wild-caught and aquaculture-sourced fisheries and increasingly to foster improved welfare and public perception of both industries. Decapod crustaceans are frequently transported live and internationally over long distances and experience anthropogenic stressors from point of capture to point of sale. Physical handling, emersion in air, and temperature fluctuations are key examples of stressors, which elicit progressive behavioral, physiological, and immunological stress responses in crustaceans. Stress responses are initiated to return the individual to a state of homeostasis; if these fail, then physiological collapse, a loss of vitality, and death will likely occur. There are several ways to mitigate the impact of stressors, reduce associated stress responses, and thus maintain quantity (survival, weight) and quality (vitality, sensorial perception) of live crustaceans. These include improved fishing techniques, better handling and operating procedures, and the introduction of proven equipment and facilities during the supply chain. The action of stressors and the effectiveness of potential mitigating strategies have been studied intensively via behavioral analysis and hemolymph sampling to ascertain changes in metabolites and the immune system. Finally, improved handling and management include global and ethical considerations, supported by relevant research, which may be achieved by adopting best practices and standards and by ensuring welfare and disease regulations.

Parasitic Crustaceans

This chapter provides a brief overview of crustacean parasites that infect commercially important fish and shellfish. Crustaceans are a diverse group of arthropods, with over 60,000 species that are significant to the aquaculture and fisheries sector, including parasitic species affecting other crustaceans, mollusks, and fishes. This chapter focuses on parasitic caligid copepods (sea lice), cymothoid isopods, and pea crabs of high economic impacts on commercially important aquatic species. The biology of the parasites, their effects on their hosts, the epidemiology of the infections, and economic impacts of these groups are described. Chemical treatments and husbandry modifications as management options for a range of crustacean parasites are presented, which includes the use of cleaner fish to remove parasites, specially designed cages to reduce infestation of parasites, or moving farms to deeper waters. The utilization of crustacean parasites as marine pest controls is further discussed, with emphasis on either its potential benefits or the negative effects on native crab populations. Despite the continuous adverse impacts parasitic crustaceans have on aquaculture, the progressive understanding of their biology and ecology may eventually lead to mitigation, if not complete eradication, of the parasites.

Crayfish Aquaculture

Crayfish have been in demand as desirable food items around the globe for centuries, and entrepreneurs have capitalized on this demand by developing and applying aquaculture principals for the intentional culture of this freshwater crustacean. The current state of the art has advanced within the last half century and is centered on a handful of species, represented by three different families, with some level of commercial production occurring on all continents except Antarctica. Procambarus clarkii (family Cambaridae), a native of south central USA, is cultured in the USA and China and easily forms the bulk of farm-raised and wild-captured crayfish globally. One North American species (Pacifastacus leniusculus) and two European species (Astacus astacus and A. leptodactylus) constitute the main cultured species from the family Astacidae and are grown in small operations throughout Europe and parts of Asia. Four species (Parastacidae), all natives of Oceania, are cultured in their native ranges and were also introduced for aquaculture in several locations around the globe. Cherax destructor and C. albidus, both commonly referred to as yabby, are medium-size crayfish and share similar life histories, whereas C. quadricarinatus (redclaw crayfish) and C. cainii (smooth marron) are larger and more valuable but have very different geographical origins. While commercial crayfish aquaculture is typically based on an extensive or semi-extensive production approach in earthen ponds, more intensive approaches may involve selective breeding, improved strains, brood or nursery phases, and use of raceways or recirculation systems. Pond size can range from 0.05 to 80 ha, depending on the species cultured. Harvesting is accomplished mainly by baited trap, although other gear and techniques are sometimes employed. Global crayfish aquaculture production has expanded significantly in the last decade, due largely to the integration of Procambarus clarkii with that of rice production in the USA and China. This integrated system of production works well because rice farming has similar requirements as crayfish aquaculture, such as clay soils, irrigation systems, and suitable climates; furthermore, the rice crop residue provides the base of the food web for furnishing sustenance to growing crayfish.

Penaeid Shrimp Aquaculture

Aquaculture supplies about 60% of the current market demand for shrimp. The entire increase for future demands must come from aquaculture since the capture from natural waters is not expected to increase. Shrimp aquaculture is conducted in many tropical and subtropical countries, but six countries—China, Indonesia, Vietnam, India, Ecuador, and Thailand—produce about 85% of cultured shrimp. Shrimp aquaculture relies on penaeid shrimp species, and two species, Litopenaeus vannamei and Penaeus monodon, account for most of the production. Shrimp aquaculture had an annual value of USD23.6 billion in 2014, making it a major item in international trade. Shrimp are produced almost exclusively in coastal ponds filled with estuarine or seawater. Small shrimp for stocking in ponds are produced in hatcheries mostly from farm-reared broodstock. Production intensity in ponds ranged from 200 to 500 kg/ha/crop in fertilized ponds to 5,000–10,000 kg/ha/crop in ponds with feeding and mechanical aeration. Up to three crops per year may be produced depending upon the location, species, and culture method. Shrimp culture can be seriously affected by viral diseases, and new diseases have been a constant threat to production success. The future of shrimp aquaculture is bright, but for it to reach its full potential, improved broodstock, high health, specific pathogen-free shrimp for stocking, better biosecurity for prevention of disease epidemics, better pond management practices, and more attention to avoiding negative environmental impacts will be necessary.

Krill Fishery

Antarctic krill is a key species in the Southern Ocean ecosystem as well as the target for the largest fishery in the Southern Ocean, which has been operating continuously since the early 1970s. The krill fishery began by operating all around the continent but gradually contracted to the West Antarctica in the 1990s, where it is currently concentrated on a few fishing grounds in the Southwest Atlantic sector. This fishery has regained some commercial attraction because of recent technological developments in harvesting and processing. These developments permit the production of high-value products, and the total annual catch has increased to nearly 400,000 t over the last decade. Climate change has already affected the krill fishery, with the reduced winter sea ice in the South Atlantic allowing current fishery operations farther south than what was previously possible. The Antarctic krill fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Its management system is unique in taking into account the state of the ecosystem as well as that of the harvested stock. The establishment of a feedback management approach for this fishery has been the major task for the Scientific Committee of CCAMLR to realize this ecosystem-based management objective. This chapter provides a general introduction to krill biology and ecology, followed by a narrative of the forces that prompted the development of a krill fishery and the current issues that surround its management.

Ecological Factors in the Emergence of Pathogens in Commercially Important Crustaceans

Several pathogens have caused significant disease issues in crustacean aquaculture and fisheries. The agents range from viruses, bacteria, fungi, protists, and even other crustaceans. They have caused direct and indirect losses to several commercial species. Many are highly specialized and require significant training to identify properly. The main causal factors involved in the emergence, transmission, and spread of disease agents in commercially important crustaceans are reviewed. The focus is on the ecological factors that lead to outbreaks, particularly the interplay between environmental, pathogen, and host factors as well as anthropogenic stressors and how these lead to or modulate outbreaks of pathogens. Examples include factors associated with outbreaks in shrimp, crayfish, and crab aquaculture as well as those in lobster and crab fisheries. The prevention and management of disease are examined in both aquaculture and fisheries settings. Although disease outbreaks are often considered unmanageable, a few mitigation strategies have been developed between aquaculture and fisheries, and some have been implemented to limit the impact of diseases on commercially important host populations, particularly in the aquaculture setting.

Marine Crustaceans as Bioindicators: Amphipods as Case Study

A bioindicator species can be defined as “an organism that provides information on the environmental conditions of its habitat by its presence or absence, and its behavior.” In this sense, crustaceans present many biological and ecological characteristics that make them particularly useful as bioindicators (e.g., widespread distribution in different habitats and geographical areas, key role in community functioning, great diversity of life history strategies). Within Crustacea, the order Amphipoda has been considered an especially relevant and suitable group due to its direct development and its special sensibility to disturbances, among other reasons. Crustaceans can be used in biomonitoring studies in a wide variety of habitats (e.g., both soft- and hard-bottom substrata from intertidal to deep environments) and for different types of environmental stressors. An extensive amount of literature has reported the sensitivity of crustacean species to heavy metal contamination, sewage and desalination discharges, or engineering and aquaculture activities, among others. Special emphasis has been placed on the role of crustaceans in the most used indexes (e.g., AMBI, BENTIX, BOPA) developed to establish the environmental quality of European coastal and marine areas. Crustaceans are one of the groups with a higher contribution to those indexes, although their presence is not necessarily indicative of low environmental disturbances. Within amphipods, the importance of the family Caprellidae as a monitoring tool in environmental programs (e.g., trace metal or tributyltin pollution) is highlighted. Alien crustaceans can also play a pivotal role as bioindicators of anthropogenic pressures, and their likely influence on the accuracy of ecological assessment programs should be taken into account. Finally, there is an increasing need to improve our scarce taxonomic knowledge in many crustacean groups since that information is vital for the correct development of monitoring tools. Studies dealing with the species’ ecological and biological traits are also encouraged in order to understand the potential application of these species as bioindicators.

Squat Lobster Fisheries

Squat lobsters have a worldwide distribution. They are very important in benthic communities of many types of environments, from intertidal zones to the deep sea. Only three of the around 1,000 known species of squat lobsters are currently a target of commercial exploitation (Pleuroncodes planipes, P. monodon, Cervimunida johni), and one has potential interest: Munida gregaria. These four species belong to the family Munididae. The main interest in fishing these species is for human consumption, although they are also important as an ingredient of pelletized food for aquaculture, as a natural source of pigments for cultured salmon, or as a supply of chitin. Squat lobster fisheries are mainly developed in Latin America, although in recent years the commercial interest of some species has also expanded to Europe, where they often dominate fishing discards. From the beginning, the fisheries of this crustacean group have shown many temporal fluctuations. As a consequence, some countries applied certain types of ban, whereas in other countries the fishery is unrestricted. As a general trend, squat lobster species with commercial exploitation denote a marked seasonal reproductive cycle associated with upwelling cycles, low oxygen zones, or high productivity areas. Then, fisheries of squat lobsters are typically associated with areas where other fisheries also occur. As a consequence, high abundances of squat lobsters show that they are interacting with other fisheries in both negative and positive ways. In this context, this chapter provides information on the biology and ecology of squat lobsters as target species, their fishing methods, the development of fisheries in the world, and their products. Finally, a brief description of the important role of these species in the ecosystems is included.

Marine Ornamental Decapods—Collection, Culture, and Conservation

Marine ornamental decapods are among the most popular invertebrates traded in the global marine aquarium industry. With the exception of the Dendrobranchiata, nearly all other major groups of decapods have at least one species traded as ornamental, the majority being caridean and stenopodidean shrimp, as well as hermit and brachyuran crabs. Found and collected in the wild from tropical coral reefs and coastal lagoons, the aquaculture of marine ornamental decapods is yet to achieve a scale that alleviates the fishing pressure affecting natural populations. Most cultivation efforts have targeted cleaner and boxing shrimp within the genera Lysmata and Stenopus, respectively. While these species are some of the most highly traded, research on their captive culture has been mainly driven by their market value rather than conservation purposes. This is likely the reason why the aquaculture of other species that are also heavily collected, such as hermit and brachyuran crabs, is yet to properly be addressed. This chapter provides an overview of the most emblematic marine ornamental decapod species currently traded for marine aquaria, including their distinctive features, as well as their collection, packing, and shipping techniques. The state of the art of marine ornamental decapod aquaculture is critically revised, with an emphasis on broodstock husbandry and maturation, larviculture, and grow-out to commercial size. Commonly employed systems for stocking breeding pairs, raising larvae, or growing juveniles are detailed, underscoring recirculated systems operating with synthetic seawater due to their potential use in coastal or inland facilities. The main bottlenecks impairing the successful breeding of these organisms are critically addressed, namely the lack of maturation diets customized to secure the nutritional needs of target species, which consequently impairs the production of high-quality larvae for cultivation. The main constraints for larviculture are also highlighted, with special emphasis on the lack of suitable live prey and the ability of several decapod species to delay metamorphosis under suboptimal larval diets. Issues on grow-out, such as poor growth performances and cannibalism, are discussed from a commercial perspective, as well as mitigation actions (e.g., use of live prey and complex shelters). There is a strong need for science-based conservation policies, where accurate data reporting and traceability along the supply chain must be implemented to promote a sustainable use of these resources. Though pricey and popular, marine ornamental decapods are no longer poorly studied when compared to a few years ago. Nonetheless, some key issues still need the attention of researchers, commercial breeders and hobbyists to ensure that these remarkable organisms can continue to be admired in the wild and in aquarium displays.

Planktonic Crustacean Culture—Live Planktonic Crustaceans as Live Feed for Finfish and Shrimps in Aquaculture

The cultivation of planktonic crustaceans as live feed is of paramount importance for the aquaculture and aquarium industries. The use of live cladocerans as feed for freshwater fish is limited to the aquarium industry, whereas Artemia and copepods are used to feed edible marine fish larvae with small mouth gape. Live feed production is expensive and time consuming; therefore, it is only used for fish that cannot be fed an inert diet directly, and only until they are ready for weaning to an inert diet. High-quality planktonic crustacean cultures are furthermore used to conduct environmental risk assessments for hazardous chemicals. Cladocerans are widely used for ecotoxicology testing, but Artemia and copepods are emerging as new model species. The present chapter reviews the culturing procedures of these important planktonic crustaceans: Artemia, cladocerans, and copepods. It discusses their use as live feed and as test organisms for environmental risk assessments. The culturing procedures are categorized into three complexity levels: Extensive, semi-extensive, and intensive. In general, the pros for Artemia and cladocerans are that they are easier to culture than copepods. Copepods are often more difficult in term of culture requirements and feeding. Nevertheless, copepods have the advantage of being in either freshwater or saline water, whereas cladocerans are limited to freshwater and Artemia to seawater. Artemia cysts and copepod eggs have a well-defined protocol for storage and distribution to aquaculture end users. Cladocerans, however, have the potential for the ephippia stage, although this is not well developed. For toxicological testing, three species are used: Artemia franciscana, Daphnia magna, and Acartia tonsa, with Artemia and A. tonsa in seawater testing, D. magna in freshwater testing. The chapter concludes with a comparative analysis of these organisms from use and culturing capability and demonstrates that there are strong similarities and challenges across these taxa.