Seaweeds, like all primary producers, require macronutrients (C, N, P) for the synthesis of organic molecules through photosynthesis to support growth and accumulation of storage compounds, including cell wall polysaccharides, for example, agar, carrageenan, and alginates, that have numerous industrial applications. The commercial production of tropical eucheumatoids has been reliant on natural streams of inorganic nutrients. Recently, the prevalent use of inorganic fertilizer in seaweed farming in the southern Philippines was allegedly initiated to boost seaweed health and avert crop failure due to pests and diseases; however, it may also be economically driven to increase biomass production with a shorter crop period that is vital for the livelihood of the marginalized coastal inhabitants. Consequently, the harvest of fast-growing but immature crops whose tissues are replete with nutrients could compromise the carrageenan yield and rheology, and, more importantly, its organic status. Moreover, the indiscriminate use and disposal of inorganic fertilizer in algoculture pose the potential for ecological disaster.
Aquaculture emerges as a crucial solution for addressing the global food shortage of an estimated 10 billion people by 2050. In Türkiye, aquaculture plays a significant role in supporting the economy and ensuring food security. Over the past two decades, finfish production in Türkiye surged from 61,163 to 547,505 t, generating $1.7 billion in export revenue across over 100 countries. This growth has been driven by technological advancements, robust governmental support, and increasing global demand for aquaculture products. However, the sector also faces persistent challenges, including the need to enhance sustainability, mitigate ecological impacts, and manage finite resources. As Europe's leading fish producer, the Turkish aquaculture sector must continue to innovate and expand to meet the demands of a growing population. Despite the expanding research on Turkish finfish aquaculture, there is no comprehensive review that consolidates both scientific progress and sectoral developments. This study fills that void by combining a bibliometric analysis of 1958 scientific publications from 1983 to 2023 with an in-depth sectoral evaluation, providing a holistic understanding of the Turkish aquaculture sector. The bibliometric analysis highlights key research areas, trends, and knowledge gaps, while the sectoral overview examines production trends, dynamics of the feed industry, technological innovations, and economic factors. It also addresses challenges such as climate change impacts, reliance on imported feed ingredients, and disease issues, discussing potential avenues for sustainable growth through innovation, policy reforms, and technological integration. This review serves as a valuable resource for researchers, policymakers, and industry stakeholders, offering insights into the current state and future directions of finfish aquaculture in Türkiye.
Among vertebrates, aquatic animals have a wide variety of body color. Yellow and red coloration, an important economic trait of aquatic animals, plays pivotal roles in ornamental value and consumption. Fish possess the most chromatophore types in vertebrates, and carotenoids primarily contribute to erythrophore and xanthophore pigmentation. Carotenoid metabolism and regulation of chromatophore development have long been a focus of selective breeding programs in fish. In crustaceans, carotenoids have been proven to be involved in enhancing coloration. However, the carotenoid requirements vary among different aquatic animals. The metabolic pathways in vivo and biochemical processes have not been well summarized. Thus, in this review, we introduced various types of carotenoids and their metabolic pathways in different aquatic species and described a similar mechanism of ketocarotenoid biosynthesis in fish and birds. We have focused on carotenoid metabolism processes and several significant genes involved in the coloration of vertebrates, such as scavenger receptors, apolipoproteins, ketolases, and β-carotene oxygenase, and their applications in aquaculture. In addition, we also summarized the current problems of carotenoid addition in diets and emphasized the importance of aquatic breeding and molecular biotechnology in carotenoid coloration and ornamental fish breeding. Finally, we provided our perspectives on fish carotenoid pigmentation research and the aquatic industry. This review will enhance our understanding of fish carotenoid metabolism as well as provide deeper insights into the molecular mechanism of fish muscle and skin pigmentation. It will benefit the production of feed additives and selective breeding for ornamental aquatic animals.
Salmonids play vital ecological and economic roles and have been introduced to many regions worldwide. When not held captive in farms, they can be classified as free-living salmonids, a group that includes native, feral, and naturalized populations, as well as fish that have escaped from aquaculture facilities. Compared to farmed salmonids, knowledge of viral infections affecting free-living populations remains limited, creating a significant gap in understanding the ecological impacts of interactions between aquaculture and natural ecosystems. To address this knowledge gap, we reviewed global reports and summarized the information on viruses infecting free-living salmonids. Most viral detections reported in the reviewed studies were found in native wild salmonids, with escaped salmon ranking second in detection frequency. Atlantic salmon (Salmo salar), sockeye salmon (Oncorhynchus nerka), and brown trout (Salmo trutta) were the most commonly reported host species. The most frequently reported viruses included infectious hematopoietic necrosis virus (IHNV), piscine orthoreovirus (PRV), infectious pancreatic necrosis virus (IPNV), and infectious salmon anemia virus (ISAV). Evidence from some studies suggests a bidirectional transmission of viruses between farmed and free-living salmonids, highlighting the complex interplay between these groups. Beyond their potential role as reservoirs for aquaculture pathogens, free-living salmonids may also be negatively impacted by viruses from farmed fish, contributing to the decline of native populations. By enhancing our understanding of the prevalence and impacts of viral infections in free-living salmonids, we can inform future research and management strategies to protect the health of both farmed and wild fish populations.
Blue carbon habitats, which exhibit high rates of natural carbon sequestration, typically refer to salt marshes, seagrass meadows, and mangrove forests. Recent studies, however, have argued for the inclusion of seaweed-dominated habitats, like kelp forests, into blue carbon frameworks. Farmed seaweed may also function as a blue carbon habitat, with large-scale seaweed aquaculture suggested as a climate change mitigation strategy, but the evidence base remains limited. Here, existing knowledge on the mechanisms influencing carbon uptake, release, transport, and storage from kelp farms was synthesised, and a literature review was conducted to quantify associated rates of carbon sequestration. We identified strong geographical and methodological biases in the literature, with the majority of studies conducted in Asia and focusing on primary production rates as a proxy for carbon sequestration potential. Estimates of carbon release and storage rates were highly variable across locations, species, and approaches, and a scarcity of research on dissolved organic carbon, sedimentary carbon, and net ecosystem productivity was identified. Although the European kelp farming industry is in its infancy, it is predicted to expand to meet increasing demand for seaweed biomass. This is incentivised by perceived associated ecosystem service benefits such as enhanced carbon sequestration. However, multiple factors including environmental concerns, a lack of quantitative evidence, operational challenges, and regulatory complexities hinder industry expansion. Based on both the synthesised empirical evidence and an examination of key barriers and knowledge gaps, we identify future challenges and research priorities needed to assess the role of seaweed farming for climate change mitigation.
Aquaculture, encompassing the cultivation of diverse saltwater and freshwater fish and shellfish species, is rapidly expanding, driven by the pressing need for sustainable food production. However, intensified farming practices often lead to significant economic losses due to fish mortality from infectious diseases and stress-related conditions. Consequently, enhancing the immune responses of farmed species has become vital for sustainable management. This has encouraged a growing interest in natural and eco-friendly bioactive compounds as alternatives to synthetic chemicals for disease prevention. Among these, polysaccharides from various natural sources have emerged as promising candidates, administered through dietary inclusion, intraperitoneal injection, or immersion. As prebiotics, these polysaccharides enhance the immunity and overall health of aquaculture species by modulating both innate and adaptive immune responses, including lysozyme activity, phagocytosis, and cytokine production. This review critically examines the latest advances in polysaccharide-induced immunoregulation, highlighting their influence on key signaling pathways, which play pivotal roles in immune modulation. Additionally, the potential of polysaccharides to mitigate stress caused by environmental factors is discussed, demonstrating their ability to enhance growth performance and disease resistance. The collective findings underscore the value of polysaccharides as sustainable alternatives to antibiotics, aligning with the increasing consumer demand for antibiotic-free aquaculture products and supporting the advancement of global aquaculture sustainability.
Triploid fish are usually sterile, a trait which reduces unwanted sexual maturation in fish farming and eliminates the risk for negative genetic effects of escapees on wild stocks. The triploid state, normally established through a doubling of the maternal genome, consists of two chromosome sets from the mother and one from the father. The increase in genome size is accompanied by an increase in cell volume and reduction in cell number that are associated with physiological effects which have been described in several studies. The doubled maternal genome is also mirrored in the triploid phenotype whereby meristic characters, growth, and physiology, are commonly biased towards that of the dam. However, chromosome doubling techniques are also known to give strong inbreeding effects. In meiotic gynogenes, this is seen in fitness-related traits such as reduced survival, especially during early life, an increase in deformities, and lower growth. The same effects on fitness, although to a milder degree, are seen in triploids, which supports the hypothesis that they are also affected by inbreeding. Producing triploids by interploidy alleviate the inbreeding problem as the tetraploids can be crossbred to increase their heterozygosity. However, producing tetraploid broodstocks is both challenging and time and resource demanding. An alternative approach is to establish a triploid founder broodstock through one generation of gynogenesis. The gynogenesis will eliminate the lethal alleles, and by selecting the best performing individuals from the best performing families, one will also partially eliminate recessive deleterious alleles, increasing the fitness of the resulting triploid population.
Cannibalism in high-value crustacean species, such as mud crab, clawed lobster, and spiny lobster, is a major impediment to commercial aquaculture due to its significant impact on survival and, hence, production. Knowledge of the nutrition acquired from consuming conspecifics may inform whether nutrient limitation is a primary reason for cannibalism, and if so, assist with feed formulation to prevent cannibalism. While feed shortages are usually not a limitation in aquaculture, nutrient limitation due to inefficient feed intake should not be disregarded, especially with formulated feeds. Additionally, unique nutrients may be absent from formulated feeds, the deficit of which may play a role in triggering cannibalism. The reasons for cannibalism in crustacean aquaculture are still unclear and possibly involve several factors, including feed availability, population density, life stages, resource competition, and prey vulnerability. In general, various forms of cannibalism exist that may have multiple drivers, including nutritional (e.g., state of hunger and lack of specific nutrient), behavioral (e.g., mating and aggression), ecological (e.g., population structure) and environmental (e.g., space limitation). In crustaceans, cannibalism occurs generally when animals are vulnerable; this may coincide with moulting events or through the lack of habitat complexity or density restrictions. The simultaneous occurrence of multiple factors influencing cannibalism in crustacean culture constitutes a major challenge for evaluating the relative significance of nutrition to cannibalism. In this review, we examine cannibalism, its drivers, and its relationship to nutrition in numerous terrestrial and aquatic species, with emphasis on crustaceans, particularly the tropical spiny lobster, Panulirus ornatus.
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