Macrobrachium rosenbergii is an economically important aquaculture species worldwide, but its reproductive efficiency is severely constrained by challenges in ovarian maturation. Methyl farnesoate (MF), a sesquiterpenoid hormone, plays a critical regulatory role in crustacean reproductive development. In this study, juvenile M. rosenbergii with an average body weight of ∼4.2 g were fed diets supplemented with different concentrations of MF (0, 3, 6, and 9 μg/g) for 56 consecutive days. The effects on growth performance, ovarian development, gut microbial composition, and related gene expression were systematically evaluated. The results showed that high-dose MF (9 μg/g) significantly promoted ovarian development, accelerated the transition of oocytes from the Oc2 to Oc4 stage, and markedly increased oocyte diameter. Hemolymph vitellogenin levels were significantly elevated during days 28–42. Concurrently, MF at high doses significantly upregulated the expression of Met, Kr-h1, and Vtg, suggesting that MF may facilitate vitellogenesis via the Met–Kr-h1–Vtg signaling pathway. Gut microbiota analysis revealed that MF reshaped microbial community structure, with the highest diversity observed in the 9 μg/g group, and dominant genera shifted to Enterobacter and Clostridium, potentially enhancing immune and metabolic capacity. In contrast, low-dose MF (3 μg/g) exhibited inhibitory effects on both growth and ovarian development. In summary, this study systematically elucidates the dose-dependent effects of MF on ovarian maturation in M. rosenbergii and reveals potential molecular mechanisms, providing a theoretical basis for efficient crustacean breeding and hormone-replacement strategies.
Nathaniel Grimes, Christopher Costello, Andrew J. Plantinga
Fisheries are vulnerable to environmental shocks that impact stock health and fisher income. Index insurance is a promising financial tool to protect fishers from environmental risk. However, insurance may change fisher's behavior. It is imperative to understand the direction fishers change their behavior before implementing new policies as fisheries are vulnerable to overfishing. We provide the first theoretical application of index insurance on fisher's behavior change to predict if index insurance will incentivize higher or lower harvests in unregulated settings. We find that using traditional fishery models with production variability only originating through stock abundance leads fishers to increase harvest with index insurance. However, fishers are adaptable and experience multiple sources of risk. Using a more flexible specification of production shows that index insurance could raise or lower harvest depending on the risk mitigation strategies available for fishers and the design of the insurance contract. We demonstrate the magnitude of potential change by simulating from parameters estimated for three Norwegian fisheries. Fisheries with index insurance contracts protecting extraction risks may increase harvest by 10% or decrease by 2% depending on the risk effects of inputs. Insurance contracts protecting stock risk will lead to 6-20% increases in harvest. Before widespread adoption, careful consideration must be given to how index insurance will incentivize or disincentivize overfishing.
Aquaculture, the farming of aquatic organisms, is a rapidly growing industry facing challenges such as water quality fluctuations, disease outbreaks, and inefficient feed management. Traditional monitoring methods often rely on manual labor and are time consuming, leading to potential delays in addressing issues. This paper proposes the integration of low-power edge devices using Tiny Machine Learning (TinyML) into aquaculture systems to enable real-time automated monitoring and control, such as collecting data and triggering alarms, and reducing labor requirements. The system provides real-time data on the required parameters such as pH levels, temperature, dissolved oxygen, and ammonia levels to control water quality, nutrient levels, and environmental conditions enabling better maintenance, efficient resource utilization, and optimal management of the enclosed aquaculture space. The system enables alerts in case of anomaly detection. The data collected by the sensors over time can serve for important decision-making regarding optimizing water treatment processes, feed distribution, feed pattern analysis and improve feed efficiency, reducing operational costs. This research explores the feasibility of developing TinyML-based solutions for aquaculture monitoring, considering factors such as sensor selection, algorithm design, hardware constraints, and ethical considerations. By demonstrating the potential benefits of TinyML in aquaculture, our aim is to contribute to the development of more sustainable and efficient farming practices.
Freshwater ecosystems are increasingly recognised as highly susceptible to anthropogenic disturbances. Because of the challenges associated with accurate population assessment, local fishery records are often utilised as proxies to infer fish population trends. However, for species with limited market size and lower commercial value, fishery records may not reliably reflect true population dynamics. This study aims to evaluate long‐term population trends of three‐lips ( Opsariichthys uncirostris ) using shore‐based lure angling surveys and to assess how recent climatic changes, particularly rising water temperatures and declining water levels, may be contributing to its continued decline along the western shore of Lake Biwa from 2011 to 2023. The results indicated a sustained decline in detection probability over the past 13 years, including in habitats with suitable substrate conditions, such as gravel or sand lake bottoms. This decline could be associated with higher water temperatures and lower water levels, especially in summer and the reproductive season. The use of shore‐based lure angling provided an alternative assessment approach independent of fishery catch data. This approach corroborated the interpretation that the long‐term reduction in fishery catches reflects a real population decrease. Although the mechanisms underlying the continued population decline remain unclear, the persistently low detection probabilities represent a critical conservation concern, particularly along the northwestern shore, where individuals intensively migrate into tributaries for reproduction.
The manipulation of species’ attributes through selective breeding can produce domesticated traits including decreased stress responses (i.e., selecting for high stress resilience). Common carp Cyprinus carpio (“carp”) have been domesticated for centuries, with domesticated forms frequently used to enhance recreational catch-and-release fisheries around the world. In Atlantic salmon Salmo salar (“salmon”), two primary strains are evident, a wild strain and domesticated aquaculture strain. Here, we compared scale cortisol concentrations (a biomarker of fish chronic stress levels) between domesticated carp in catch-and-release pond fisheries and wild carp in waters with no angling. Carp of low scale cortisol concentration were apparent in all sampled populations, suggesting individuals of low stress sensitivity are encountered in both wild and domesticated strains, and in natural and captive environments. Carp with relatively high levels of scale cortisol were, however, only present in wild carp, suggesting high phenotypic variability in their chronic stress responses, with some individuals being highly sensitive to stress. In some wild carp, elevated scale cortisol concentrations could also have been indicative of adaptive responses to their heterogenous environments. We then compared wild versus farmed salmon scale cortisol levels, and found a similar pattern, with relatively high scale cortisol levels only detected in wild fish. These results indicate that while domesticated carp and salmon are exposed to potentially stressful environments, they appear to have some resilience against the adverse effects of chronic stress.
Numerous studies have reported that environmental background color alters the skin color of aquaculture fish. In the present study, we investigated the effects of light intensity on skin coloration, chromatophores numbers, astaxanthin content and gene expression in 7-month-old coral trout Plectropomus leopardus. After been feeding astaxanthin-free diet (AFD) for 30 days, the fish in control group (under natural light) showed little change in skin color. In contrast, the skin color of fish in light-treat group (under 300 lux white light) changed from dark-brown to orange-red, associated with erythrophores number increase, xanhtrophores number reduction and astaxanthin amount increase on the skin. Transcriptomic analysis indicated that several genes related to carotenoid transport, metabolism, cell apoptosis and autophagy show significant variation between the light-treat and control groups. These results suggest that background light intensity affect the proliferation of erythrophores and the acquisition of astaxanthin in the skin of coral trout.
Aquaculture plays a vital role in global food security and coastal economies by providing sustainable protein sources. As the industry expands to meet rising demand, it faces growing challenges such as disease outbreaks, inefficient feeding practices, rising labor costs, logistical inefficiencies, and critical hatchery issues, including high mortality rates and poor water quality control. Although artificial intelligence has made significant progress, existing machine learning methods fall short of addressing the domain-specific complexities of aquaculture. To bridge this gap, we introduce AQUA, the first large language model (LLM) tailored for aquaculture, designed to support farmers, researchers, and industry practitioners. Central to this effort is AQUADAPT (Data Acquisition, Processing and Tuning), an Agentic Framework for generating and refining high-quality synthetic data using a combination of expert knowledge, largescale language models, and automated evaluation techniques. Our work lays the foundation for LLM-driven innovations in aquaculture research, advisory systems, and decision-making tools.
Christoffer Nagel, David Goldbrunner, J. Knott
et al.
Stocking fish is a common practice in fisheries management, particularly for species of high conservation value or economic importance. Despite its widespread use, systematic evaluation of fish stockings remains scarce. This includes non‐native species such as rainbow trout ( Oncorhynchus mykiss ), which are intensively stocked into European water bodies for recreational angling. Rainbow trout used for stocking into the German River Inn are sourced from various hatcheries, likely contributing to differences in their physical condition which may affect post‐stocking survival. This study provides a baseline assessment of the physical condition, focusing on morphometric traits and external injuries, of rainbow trout prior to stocking in this large alpine river. We analyzed 150 individuals from five aquaculture facilities using morphometric measurements and standardized injury assessment protocols. Rainbow trout showed a high level of morphometric plasticity associated with their origin. All examined fish had visible external injuries, with the most frequent ones being tears and amputations on the caudal and dorsal fins, as well as scale loss. Up to 11 of 22 possible injury types were identified in the most severely affected individuals, and specific external injury patterns could be related to specific hatcheries. These findings offer important baseline data on the physical condition of stocked rainbow trout and provide a foundation for interpreting future studies on their performance in the wild.
Digital aquaculture leverages advanced technologies and data-driven methods, providing substantial benefits over traditional aquaculture practices. This paper presents a comprehensive review of three interconnected digital aquaculture tasks, namely, fish tracking, counting, and behaviour analysis, using a novel and unified approach. Unlike previous reviews which focused on single modalities or individual tasks, we analyse vision-based (i.e. image- and video-based), acoustic-based, and biosensor-based methods across all three tasks. We examine their advantages, limitations, and applications, highlighting recent advancements and identifying critical cross-cutting research gaps. The review also includes emerging ideas such as applying multi-task learning and large language models to address various aspects of fish monitoring, an approach not previously explored in aquaculture literature. We identify the major obstacles hindering research progress in this field, including the scarcity of comprehensive fish datasets and the lack of unified evaluation standards. To overcome the current limitations, we explore the potential of using emerging technologies such as multimodal data fusion and deep learning to improve the accuracy, robustness, and efficiency of integrated fish monitoring systems. In addition, we provide a summary of existing datasets available for fish tracking, counting, and behaviour analysis. This holistic perspective offers a roadmap for future research, emphasizing the need for comprehensive datasets and evaluation standards to facilitate meaningful comparisons between technologies and to promote their practical implementations in real-world settings.
José António Filipe, Manuel Alberto M. Ferreira, Manuel Coelho
et al.
The problems raised by anti-commons and bureaucracy have been linked since the study of Buchanan and Yoon (2000). Bureaucracy involves a multitude of agents that have deciding power. At the view of conflicting interests, the decision makers inertia or the inertia of the system itself, excessive administrative procedures or too many administrative circuits push for too late decisions, or for non-rational decisions in terms of value creation for economic agents. Property Rights Theory explains new concerns. Considering that an anti-commons problem arises when there are multiple rights to exclude, the problem of decision process in aquaculture projects makes sense at this level. However, little attention has been given to the setting where more than one person is assigned exclusion rights, which may be exercised. Anti-commons problem is analyzed in situations in which resources are inefficiently under-utilized rather than over-utilized as in the familiar commons setting. In this study, fisheries problems are studied and some ways to deal with the problem are presented.
Herman B. Amundsen, Marios Xanthidis, Martin Føre
et al.
Aquaculture is a big marine industry and contributes to securing global food demands. Underwater vehicles such as remotely operated vehicles (ROVs) are commonly used for inspection, maintenance, and intervention (IMR) tasks in fish farms. However, underwater vehicle operations in aquaculture face several unique and demanding challenges, such as navigation in dynamically changing environments with time-varying sealoads and poor hydroacoustic sensor capabilities, challenges yet to be properly addressed in research. This paper will present various endeavors to address these questions and improve the overall autonomy level in aquaculture robotics, with a focus on field experiments. We will also discuss lessons learned during field trials and potential future prospects in aquaculture robotics.
Sebastian Quaade, Andrea Vallebueno, Olivia D. N. Alcabes
et al.
Aquaculture production -- the cultivation of aquatic plants and animals -- has grown rapidly since the 1990s, but sparse, self-reported and aggregate production data limits the effective understanding and monitoring of the industry's trends and potential risks. Building on a manual survey of aquaculture production from remote sensing imagery, we train a computer vision model to identify marine aquaculture cages from aerial and satellite imagery, and generate a spatially explicit dataset of finfish production locations in the French Mediterranean from 2000-2021 that includes 4,010 cages (69m2 average cage area). We demonstrate the value of our method as an easily adaptable, cost-effective approach that can improve the speed and reliability of aquaculture surveys, and enables downstream analyses relevant to researchers and regulators. We illustrate its use to compute independent estimates of production, and develop a flexible framework to quantify uncertainty in these estimates. Overall, our study presents an efficient, scalable and highly adaptable method for monitoring aquaculture production from remote sensing imagery.
Muskellunge are a valuable sportfish species which has been stocked throughout North America. Stocking is a strategy to generate angling opportunities by introducing species to waterbodies that otherwise would not have contained the fish, such as impoundments and reservoirs. Therefore, understanding the ways fish interact with different waterbodies is critical for managers to understand. To that end, we utilized a year‐long passive telemetry study with muskellunge in a reservoir known for its muskellunge angling. Additionally, we employed temperature loggers to track lake temperatures. We found that smaller female muskellunge were more resident at sites compared to similar‐sized males, although fish did not exhibit site‐specific preferences. We also found that fish moved high distances over the course of the year without time‐specific differences. Furthermore, we found evidence that muskellunge was selected for thermal refuges in the reservoir; however, in summer, when water temperatures were elevated, fish inhabited water, which has been shown to increase incidental mortality. The results of this study indicate a need for muskellunge managers, especially in reservoirs, to consider water temperature in angling regulations. Additionally, our results highlight a need for adding habitat structure in reservoirs and altering stocking densities of fish. Collectively, these results will help inform managers on muskellunge spatial interactions within a reservoir and achieve management goals.
Abstract The literature on global trends in recreational fishing, the determinants of participation in recreational fishing, and the social embedding of recreational fishing in the public eye are reviewed across the world. Data support a conceptual life-cycle model of fisheries according to which interest in recreational fishing rises rapidly with economic development before leveling off and eventually declining. Participation in recreational angling across the globe varies substantially and is directly related to societal-level developments affecting resources, time, and socialization into fishing. Moreover, culture and the way that fish are historically situated within society appears to affect interest in fishing and the public perception of certain fishing practices. Across the more developed western countries, a sustained shift in public values from anthropocentric to more biocentric viewpoints is documented. This shift puts traditional fisheries management that manages ecosystems for optimal fishing experiences under increasing scrutiny and elevates biodiversity conservation toward a key goal of contemporary fisheries management in many countries. However, while a pro fish welfare discourse can be traced to almost all developed countries covered in this review, this does not mean the recreational activity is threatened or welfare-oriented regulations are widely implemented, with a few exceptions in selected countries. Public surveys conducted in mainly developed countries around the world instead reveal that people generally view recreational fisheries as an acceptable pastime. Major structural changes are occurring in many societies related to immigration, increasing ethnic and cultural diversity of populations, and social value change. Yet, little is known how these changes might affect recreational fishing participation and behavior, and the view of the general public toward fishing in the future. Panel research designs that repeatedly survey the public, and recreational fishers, will be needed to track value and participation changes over time, but such designs are rarely implemented in most countries that were reviewed in this work. Data gaps are particularly strong for Africa and large parts of Central and South America as well as Russia and Asia.
Abstract Adult returns to many Atlantic salmon wild and hatchery stocks of the North Atlantic have declined or collapsed since 1985. Enhancement, commercial fishery closures, and angling restrictions have failed to halt the decline. Human impacts such as dams, pollution or marine overexploitation were responsible for some stock declines in the past, but adult returns to river and hatchery stocks with no obvious local impacts have also declined or collapsed since 1985. Multiple studies have postulated that the recent widespread occurrence of low adult returns may be caused by climate change, salmon farming, food availability at sea, or marine predators but these possibilities are unsupported by stocks that persist near historic levels, loss of stocks remote from farm sites, a diverse marine prey field, and scarcity of large offshore predators. The decline and collapse of stocks has common characteristics: 1) cyclic annual adult returns cease, 2) annual adult returns flatline, 3) adult mean size declines, and 4) stock collapses occurred earliest among watersheds distant from the North Atlantic Sub-polar Gyre (NASpG). Cyclic annual adult returns were common to all stocks in the past that were not impacted by anthropogenic changes to their natal streams. A flatline of adult abundance and reduction in adult mean size are common characteristics of many overexploited fish stocks and suggest illegal, unreported, and unregulated (IUU) fisheries exploitation at sea. Distance from the NASpG causing higher mortality of migrating post-smolts would increase the potential for collapse of these stocks from IUU exploitation. By-catch of post-smolts and adults in paired-trawl fisheries off Europe and intercept adult fisheries off Greenland, in the Gulf of St. Lawrence, and off Europe have been sources of marine mortality but seem unlikely to be the primary cause of the decline. Distribution in time and space of former, legal high-sea fisheries indicated fishers were well acquainted with the ocean migratory pattern of salmon and combined with lack of surveillance since 1985 outside Exclusive Economic Zones or in remote northern regions may mean high at-sea mortality occurs because of IUU fisheries. The problem of IUU ocean fisheries is acute, has collapsed numerous stocks of desired species worldwide, and is probably linked to the decline and impending collapse of the North Atlantic salmon population.
Abstract Largemouth Bass (Micropterus salmoides, LMB) and Smallmouth Bass (Micropterus dolomieu, SMB) are among the most highly invasive species across the globe, but are simultaneously among the most highly sought-after game fish. To explain these disparate views, data on invasive status and angling participation of these two species were compiled at the country level. Largemouth Bass were found established in 62 countries on five continents, whereas SMB were found established in only nine countries on the same five continents. Invasive risk assessments were disparate between the species, with more for SMB (N = 29) than LMB (N = 27). In every instance save one (Finland), SMB were considered “invasive” compared to LMB, which were “invasive” in only 74% of assessments. Twenty-eight countries with non-native black bass have groups that participate in high-profile fishing tournament such the Black Bass World Championship, BASS (Bass Anglers Sportsmans Society) Nation, and Major League Fishing. Most countries with fishing tournaments occur in countries with established LMB populations than in countries with established SMB populations, suggesting a greater economic importance on LMB fishing. The struggle between conserving biodiversity and relying upon economic benefits from fishing for introduced species is a wicked problem likely to continue into the future.
Abstract Accumulating evidence has demonstrated a decrease in post-release survival of angled Atlantic salmon (Salmo salar) during periods of warm water temperatures. Consequently, the application of water temperature-related fishery closures by resource managers is gaining interest. Here, the role of water temperature-related fishery closures in recreational Atlantic salmon fisheries is reviewed by (1) presenting a synopsis of factors that could influence the effectiveness of these fishery closures, (2) using novel fisheries and water temperature data from Eastern Canada, to illustrate how various closures can affect management outcomes, and (3) discussing alternative options for managers to implement such fishery closures. Results suggest there are a number of considerations when implementing a water temperature-related fishery closure. For populations meeting conservation requirements, results show that additional angling opportunities can occur at minimal conservation cost by applying morning-angling-only protocols in rivers during periods of reduced catch and release and moderately warm water temperatures. The impact on salmon populations, however, will be higher in situations where high catch and release rates overlap with warm water periods (e.g. when day-night water temperatures remain in excess of 20 °C or remain high during the summer) or occur over prolonged periods of extreme warm water temperatures. In situations where resource managers have few resources and need to implement water temperature-related fishery closures on a large spatial scale, it is recommended that strategically chosen index rivers to inform water temperature-related fishery closures are used. In rivers with healthy salmon populations, angling opportunities during periods of warm water could be considered if supported by enhanced monitoring (e.g., monitoring salmon abundance, spatially-structured water temperature data, and mandatory catch reporting (catch and effort)) that optimize tradeoffs between socio-economic benefits and conservation.
Speckled peacock bass Cichla temensis is a popular sport and food fish that generates substantial angling tourism and utilitarian harvest within its range. This popularity and value make this species important for management and a potential aquaculture candidate for both fisheries enhancement and food fish production. However, little is known of optimal conditions in natural habitats which also are important for development of hatchery protocols for handling, spawning, and grow-out. Speckled peacock bass have been documented to have high sensitivity to extreme temperatures, but the metabolic underpinnings have not been evaluated. In this study, the effects of temperature (25, 30, and 35°C) on standard metabolic rate (SMR) and lower dissolved oxygen tolerance (LDOT) of juvenile speckled peacock bass (mean ± standard error total length: 153 ± 2 mm, and wet weight: 39.09 ± 1.37 g) were evaluated using intermittent respirometers after an acclimation period of 2 weeks. Speckled peacock bass had the highest SMR at 35°C (345.56 ± 19.89 mg O2 /kg/hr), followed by 30°C (208.16 ± 12.45 mg O2 /kg/hr), and 25°C (144.09 ± 10.43 mg O2 /kg/hr). Correspondingly, the Q10 , or rate of increase in aerobic metabolic rate (MO2 ) relative to 10°C, for 30-35°C was also greater (2.76) than from 25-30°C (2.08). Similarly, speckled peacock bass were the most sensitive to hypoxia at the warmest temperature, with a LDOT at a pO2 of 90 mmHg (4.13 mg/L) at 35°C compared to pO2 's of 45 mmHg (2.22 mg/L) and 30 mmHg (1.61 mg/L) at 30°C and 25°C, respectively. These results indicate speckled peacock bass are sensitive to temperatures near 35°C; therefore, we recommend managing and rearing this species at 25-30°C.