Indian reservoirs offer tremendous scope but fish production remains below potential. The present study evaluates the effectiveness of fish seed stocking on the yield of 62 reservoirs of Tamil Nadu, India during 2011–2020. The results indicate that all large (>50 km 2 ), 64.1% of the medium (10−50 km 2 ) and 50.7% of small (<10 km 2 ) reservoirs are under-stocked with less than <50% of the recommended stocking density. The stocking efficiency was found to be lowest in large (0.05), medium (0.11) and highest in small reservoir (0.26). The regression analysis showed significant positive associations between stocking density and yield in small ( R 2 =0.05), medium ( R 2 =0.31) and negative in large ( R 2 =0.008) reservoirs. The mean annual yield during the studied period was highest in small (137 kg ha −1 yr −1 ), followed by medium (86.64 kg ha −1 yr −1 ) and, large (46.1 kg ha −1 yr −1 ) reservoirs. The study indicated that insufficient availability of fingerlings and inconsistency in the seed quality as the major stumbling blocks in achieving the estimated production potential. It is suggested to improve the hatchery facility, adoption of enclosure culture for rearing fish fingerlings, creating awareness among the stakeholders to optimize the fish production from these resources and also for ensuring improved livelihood of the fishers dependent on this sector. This is the first long-term, state level evaluation of reservoir stocking in Tamil Nadu, complementing past national studies. These findings highlight the importance of optimal stocking density, advanced fingerling use, and cooperative-based management for sustaining fish production and fisher livelihoods in Tamil Nadu.

With the intensification of fish cultivation, also increased threat of parasitic diseases to fish health, growth, production, and productivity. This has had huge negative impacts and necessitate alternative therapeutics for the control and treatment of diseases. Medicinal plants have been integral to human life, utilized as a natural source of bioactive compounds for use in veterinary and human medicine. These plants produce diverse chemical compounds, such as alkaloids, saponins, phenolic compounds, tannins, terpenoids, steroids, flavonoids, and essential oils, which have been used in fish aquaculture. Thus, the present study aimed to synthesize papers published within the last eight years on the efficacy of different extracts, essential oils, and bioactive compounds derived from medicinal plants, as well as their potential modes of action on fish parasites, with an emphasis on fish parasitic monopisthocotylans and polyopisthocotylans (formerly monogeneans). Data on phytotherapeutic products, phytochemicals, targeted parasites, and in vitro and in vivo experiment outcomes were extracted from the literature and summarized. Additionally, the mechanisms by which these phytotherapics act on parasites were shown and discussed. The bioactivity of essential oils and crude herbal extracts in controlling and eliminating parasites is directly linked to the action of their major components, which demonstrate parasiticidal and anti-monopisthocotylans and polyopisthocotylans activity, even when isolated. This provides a wide range of options. Phytotherapeutic agents are an alternative to chemotherapeutic agents because they pose no risk of acute or chronic toxicity to host fish, nor do they contaminate handlers. They also do not cause parasitic resistance and are environmentally friendly. Therefore, they are recommended for use in management strategies to control and treat parasite infections in fish aquaculture due to their anthelmintic and parasiticide properties. Lastly, although the economic and aquaculture viability of phytotherapeutic agents is unknown, the environmental benefits are evident compared to the widespread use of chemotherapeutics.

The tall sea pen Funiculina quadrangularis (Pallas, 1766), a widespread octocoral species found in Mediterranean soft-bottom habitats, is recognized by the Food and Agriculture Organization of the United Nations as a vulnerable marine ecosystem indicator due to its sensitivity to bottom trawling. Adapted to stable environments, its distribution could be affected by the combined impacts of climate change, particularly warming bottom waters, and trawling activities. Records from the Mediterranean International Trawl Survey program and other sources were used in an ensemble species distribution modelling approach to predict current habitat suitability and project potential habitat shifts under the intermediate IPCC climate scenario SSP2–4.5 for 2050 and 2100. Results indicated a widespread distribution across the Mediterranean continental shelf and slope, with the species typically found between 100 and 750 m depth (occasionally as shallow as 20 m) and tolerating temperatures between 12°C and 16°C. By 2050, over 80% of the current habitat was projected to remain suitable. However, only 50% were expected to serve as climate refugia by 2100, likely due to warming bottom waters and increased salinity. Some habitat gains were projected (e.g., Ligurian Sea, Corsican waters, deep Eastern Mediterranean), but uncertainties persist regarding the species’ ability to colonize these new areas. Despite its presence in trawled areas, suggesting a relatively lower fishing pressure sensitivity than other VME taxa, significant habitat shifts were projected under future climate conditions. Therefore, it is essential to prioritize conservation efforts in areas projected to remain suitable over time. The climate refugia identified through this study offer critical guidance for future climate-smart VME management plans, helping to ensure the long-term survival of F. quadrangularis in the Mediterranean Sea.

Global aquaculture production has expanded rapidly in recent decades, resulting in a significant increase in effluent discharge rich in phosphorus and nitrogen. In freshwater and brackish water ecosystems, phosphorus is often the primary limiting nutrient. Environmental sustainability of aquaculture, therefore, hinges on reducing phosphorus in its effluents, particularly urinary phosphorus due to its soluble nature, which can directly contribute to eutrophication and harmful algal blooms such as red tides. In contrast, fecal phosphorus, which is primarily insoluble, poses a lower environmental risk. However, much of the past research has focused on improving phosphorus digestibility to reduce fecal phosphorus excretion, while urinary phosphorus has been largely overlooked. Urinary phosphorus represents the excess phosphorus absorbed from the diet. Therefore, dietary strategies should aim to reduce the available phosphorus content in fish feed to just below their nutritional requirements, ensuring that fish growth and health are not compromised. This approach could significantly reduce or even eliminate urinary phosphorus excretion, greatly enhancing the sustainability of aquaculture. This review highlights key aspects of urinary phosphorus and examines various strategies for its reduction, with a focus on practical in situ techniques.

The prevalence of sailfin catfishes (Pterygoplichthys spp.) in inland waters, including vast aquaculture systems of India is rising. This might be a serious threat to the country’s native freshwater biological resources and aquaculture production. Therefore, studies were carried out to evaluate the impact of Amazon sailfin catfish Pterygoplichthys pardalis on different life-stages of native fishes. First, we analyzed the impact of three different size classes (small: 9.95 ± 0.70 cm, medium: 21.74 ± 0.87 cm and large: 30.81 ± 1.59 cm total length) of Amazon sailfin catfish on the survival of early life-stages (eggs, hatchlings, first-feeding fry, and 10-day-old fry) of two native fishes; native carp Labeo rohita (rohu) and native catfish Ompok bimaculatus (butter catfish). All size classes of Amazon sailfin catfish showed preference towards fish eggs over aquatic macro-invertebrates (Tubifex worms) and ingested over 90% of the eggs of both the native species. However, their effects on native species’ mobile life stages (hatchlings forth) were found to be insignificant in terms of mortality. We then assessed the competition between advanced stages (fingerlings, advanced fingerlings, and sub-adult) of the Amazon sailfin catfish and the native fishes by evaluating growth and survival in three different experimental setups (indoor tanks with artificial feeds; outdoor tanks with natural food and artificial feed; and earthen pond with natural food) and in different combinations for a period of three to six months. In indoor experiment, no discernible impact of Amazon sailfin catfish on the growth of fingerlings of native species was found. But, in the outdoor experiment, growth of advanced fingerlings of rohu and butter catfish was decreased by 18.8–23.4% and 28.9–36.7%, respectively, in low- and high-biomass Amazon sailfin catfish treatments. The growth of rohu and butter catfish sub-adult was also reduced in the pond experiment, by 29.7% and 32.2%, respectively. However, impact of Amazon sailfin catfish on survival of native fish species at advanced stages was found minimal. Overall findings of this study indicate that sailfin catfish may have an adverse effect on the survival and growth of native fishes by either directly consuming or destroying native fish eggs or by competing with them for food and space.

Throughout all stages of fish conservation and aquaculture development, genetic and genomic approaches can be leveraged to enhance understanding of the diversity and complexity of these organisms, including the linkage between phenotype and genotype, and their adaptive and breeding potential. These approaches can inform processes ranging from the initial collection of wild broodstock to the ongoing use of genomic selection on domesticated lines. Due to the diversity in cultured fish species, small and medium enterprises (SMEs) commonly explore new species for culture, or work with species within a narrow regional conservation or commercial focus. These enterprises face obstacles in utilising genetic and genomic approaches due to development and implementation costs, specialised skill set requirements, and infrastructure and labour limitations; yet the benefits often outweigh these challenges. Choosing the best molecular genetic or genomic tools depends on programme goals and species, but small and medium enterprises may miss opportunities to acquire more information through their current approaches, or not realise what may be gained through modest investments in genomic tools. To provide better insight and promote discussion and collaboration between culturists and genomic practitioners, we define and describe five States of development and application of genetic and genomic tools frequently observed in aquaculture and conservation breeding programs. We characterise these tools, their general applications, and how current technologies allow programs to advance to higher States without following a sequential progression, a concept we refer to as “State skipping”. This document outlines the available molecular genetic and genomic tools, but does not cover animal breeding or the science behind it. Similarly, bioeconomic models are not included, although relative economic costs and benefits are highlighted. The technical considerations and limitations of various approaches are reviewed, along with available resources for those seeking further support in exploring genetic and genomic tools in breeding programmes.

Shrimp farming in Sri Lanka is economically advantageous but faces challenges like disease outbreaks and environmental issues. The government has introduced Best Management Practices (BMPs) to ensure sustainability. This study aimed to assess BMP knowledge and adoption among Sri Lankan shrimp farmers while identifying socio-demographic and behavioral factors influencing them, which have not been previously assessed. Data were gathered from 131 shrimp farmers in Puttalam district in Sri Lanka through a questionnaire survey and analyzed using descriptive statistics and ordered logistic regressions. The results showed that 26% of farmers had poor BMP knowledge, while 37% each had fair and good knowledge. Regarding adoption, 2% exhibited poor, 89% fair, and 9% good BMP adoption. According to the ordered logistic regression results, BMP training (p < 0.01), education (p < 0.05), and workforce (p < 0.05) significantly affect the knowledge level of BMPs. In contrast, age (p < 0.05), experience (p < 0.05), income share (p < 0.1), and risk preference (p < 0.1) significantly affect the adoption of BMPs. It is recommended to provide more BMP training to shrimp farmers, to improve their knowledge. Moreover, considering socioeconomic and behavioral factors is crucial when designing policies and interventions to promote BMP adoption.

This study investigates the network of causal relationships in the king’s littleneck clam ( Ameghinomya antiqua ) fishery in the southern zone of the Los Lagos Region, Chile, using the Convergent Cross Mapping (CCM) method. The dynamics of the system were analysed based on four time series: abundance indices derived from landings per unit effort (LPUE), the percentage of mega-spawners (Mega) in catches, landings and sea surface temperature (SST) anomalies. The study identified a significant unidirectional causal relationship between landings and landings per unit, and between sea surface temperature and catch per unit effort. A marginally significant one-way causal relationship between landing and mega-spawners was found. A unidirectional causal relationship was also observed from temperature to landings; the extended CCM suggested that landings respond with a lag of 2-4 months to changes on SST. Landings and LPUE were driven by the shared environmental force (sea surface temperature). The results suggested that controlling landings rates can influence management decisions aimed at regulating resource conservation, using a precautionary approach and a target reference value for LPUE. The importance of incorporating indicators such as mega-spawners into management strategies is highlighted, as they can be indicators of the stock’s health status. This study improves the comprehension of how environmental and socio-economic factor interact in complex system.

European oysters (Ostrea edulis) once covered large areas of the North Sea, but have disappeared due to a combination of overexploitation and the destruction of benthic habitats including hard settlement substrate. Offshore wind parks offer an opportunity for oyster restoration as fishing is banned inside these parks and scour protection provides hard settlement substrate. However, ecological restoration of marine systems is capital-intensive. The success of restoration projects is mainly determined by the choice of methods and techniques and consequently costs. Costs and cost-effectiveness information are therefore key in decision making processes concerning the selection of restoration efforts and techniques. So far, economic viability of marine ecosystem restoration have mainly focused on near-shore shallow habitats. The aim of this study was to provide insight into the most cost-effective deployment options to create a European flat oyster reef in an offshore wind farm in the North Sea. Within the current policy and legislation framework, several deployment scenarios were identified based on best practices, expert knowledge, and preliminary results of several pilots. The 9 scenarios included ‘adults placed loose on the seafloor’, ‘adults glued on granite’, ‘spat settled on shells’, ‘spat settled on granite’ and a combined ‘adult and spat’ scenario. Cost-effectiveness of the different scenarios was determined by modelling the expected reef biomass post-deployment both with and without the option to add additional settlement substrate post-deployment. The main conclusions from this exercise were that: 1. based on investment value, the scenarios ‘adult loose on the seafloor’, ‘adults in cages’ and ‘spat on shells’ had the highest revenues per Euro invested; 2. adding substrate in the years post-deployment increased cost-effectiveness in the model for all scenarios, and 3. the time post-deployment to reach a self-sustaining adult oyster population was, with 8–10 yr, shortest for the scenarios 'spat settled on shells' and the combined scenario of 'adults placed loose on the seafloor' and 'spat settled on shells'.

The experiment was intended to evaluate the competent restricted feeding strategy for amur common carp fingerlings reared under actual pond condition. Fingerlings (2.28 ± 0.27 g) were subjected to five different restricted feeding regimes; viz. TC (daily feeding), T1/1 (1-day feeding/ 1-day starvation), T2/1 (2-days feeding/ 1-day starvation), T2/2 (2-days feeding/ 2-days starvation), and T1/2 (1-day feeding/ 2-days starvation). The results indicated significantly similar (P > 0.05) growth pattern in T2/1, when compared to TC. But in other feed-deprived groups the fish growth was much poor. In T2/1, the feeding strategy had no significant adverse effect on SGR; rather it supported improved nutrient utilization indices. T2/1 asserted superior digestive capacity in the starved group, with elevated (P < 0.05) protease and amylase activity. Reduced (P < 0.05) hepatic lactate dehydrogenase and malate dehydrogenase activity in T2/1 group suggests reduced stress, which might strengthen compensatory growth. Feed deprivation increased (P < 0.05) both alanine aminotransferase and aspartate aminotransferase activity in blood. In the current study, elevated (P < 0.05) level of hepatic superoxide dismutase, catalase, glutathione peroxidase activity and Insulin like growth factor 1 and reduced (P < 0.05) blood glucose level, parallel to the degree of starvation was also evidenced. The present study suggests that 2-day feeding followed by 1-day feed restriction (T2/1) as the best feeding strategy for pond culture of amur common carp with the highest net return without compromising the growth, yield and antioxidative status.