Water Stocks Research Articles

Patagonian toothfish (Dissostichus eleginoides) stocks in South American waters and its implications for fishery management

Patagonian toothfish (Dissostichus eleginoides) is a highly prized resource in markets due to the quality of its meat. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) implemented controls and regulations in response to the sharp rise in the illegal fishing of D. eleginoides in the 1990s. Today, four fisheries in waters close to the southern tip of South America are managed in accordance with stringent sustainability standards. Even though they are separate management units, both abundance assessments and annual catch allocations are conducted using different criteria regarding stock considerations across the region, leaving one of the fundamental premises of fisheries management unclear. This study examines historical data and recent research to explore the potential differentiation between Patagonian toothfish populations in South American waters, which is crucial for the management of diverse fisheries. Genetic studies, otolith microchemistry, morphometry, parasitic fauna, tagging programs, reproductive characteristics, and the impact of ocean circulation on dispersal and recruitment were analyzed. Tagging studies in the southern hemisphere oceans confirm the species’ affinity to specific habitats, suggesting minimal fish exchange between South American fishing grounds. From a fisheries perspective, this review suggests the existence of distinct stocks of the species structured along the shelf and slope of the southern cone of America based on reproduction areas along the continental shelves and slope, the diverse parasitic fauna, the variability in stable isotopes and trace elements of otoliths, and the little significant exchange of fish between current fishing grounds. All of this could lead to considering the D. eleginoides fishery as independent exploitation units.

Trends and status of harbor seals in Washington State, USA (1977–2023)

AbstractHarbor seal (Phoca vitulina) numbers in the United States rebounded after the implementation of conservation measures associated with the Marine Mammal Protection Act of 1972 (MMPA). Stock estimates are a critical tool for assessing species status and management options under the MMPA and for modeling efforts designed to evaluate the role of pinnipeds in marine ecosystems. We conducted aerial surveys of harbor seal haul‐out sites between 1977 and 2023 to estimate population size and trends in four Washington State, USA, stocks: (1) Hood Canal, (2) Southern Puget Sound, (3) Washington Northern Inland Waters, and (4) the Washington portion of the Oregon‐Washington Coastal Stock. We fit a Bayesian state‐space model to estimate population trends for all stocks, as well as the Washington Coast region, and present carrying capacities and maximum net productivity levels for all stocks. The most recent population estimates for the three inland water stocks are within their optimal sustainable population range, with some evidence that the Southern Puget Sound Stock is continuing to grow.

Towards Cross-Border Fisheries Management: An Analysis of Fleet Structures and Species-Specific Regulatory Measures in the Aegean Sea

Intrinsic differences in the applied management measures of shared stocks in transboundary waters inhibit the ability of either state to benefit from such measures, as one state may benefit in lieu of the other, thus reducing the efficacy of both. This study compares for the first time the fleet structure, specific management measures applied to species-specific regulations for commercial fishing, species listed in official monitoring schemes, and protected taxa between Greece and Türkiye for the Aegean Sea. A comparative analysis utilizing the official data was sourced from both countries. Large-scale Greek and Turkish fishing fleets have been modernized within the last 30 years (1991-2021). Greek and Turkish large-scale fishing fleets included smaller trawlers with lower tonnage and slightly higher engine horsepower, while purse seines of both states included larger vessels with higher horsepower and tonnage. This indicates that the fishing pressure on the demersal resources in the Aegean Sea has partially decreased, but the fishing pressure on pelagic resources has increased despite the decrease in the number of vessels. Only 11 out of 74 minimum conservation reference sizes (MCRS) are sufficiently set above the Lm50 sizes they should be based on, whereas 18 species need reproductive studies, and 22 are set below the Lm50, and could benefit from an increase. The application of specific closed seasons for commercial species was used by both states with the intent to protect the reproductive periods of some stocks. However, several of these closure periods did not fully or even partially cover the spawning periods of the respective species. Species-specific closures were applied to 13 species in Greece and 23 species in Türkiye, with only two fish species (Xiphias gladius and Thunnus thynnus) listed for both countries. Only 14 species (out of 34 protected by Greece and 46 by Türkiye) are protected by both states, most of which are listed as critically endangered by the International Union for Conservation of Nature and Natural Resources (IUCN). Harmonization of fisheries management measures currently does not align between the two neighbouring states, and the General Fisheries Commission of the Mediterranean is the competent authority that would be able to restructure such measures, especially as Türkiye has been aligning their measures with that of the EU for the accession process. This contribution highlights the clear differences between Greece and Türkiye, and provides advice for developing a unified management regime for the Aegean Sea.

Stability Studies of the Dilution Series of Different Antibiotic Stock Solutions in Culture Medium Incubated at 37 °C.

The long-term stability of antibiotics in culture media remains underexplored in scientific literature. This study evaluated the stability of eight distinct antibiotic stock solutions-amoxicillin, cefotaxime, neomycin, oxytetracycline, florfenicol, enrofloxacin, colistin, and potentiated sulfonamide-and their 10-fold dilution series in tryptone soy broth (TSB) at 37 °C, over 12 days. Samples were collected immediately after preparation and on days 1, 2, 5, 7, 9, and 12, with active substance concentrations measured using ultra-high-performance liquid chromatography (UHPLC) coupled with mass spectrometry. The results indicated that among the ultrapure water stock solutions, neomycin, florfenicol, and potentiated sulfonamide maintained stability (>95%). Within the culture medium, florfenicol showed consistent stability (100%) throughout the study, potentiated sulfonamide experienced minor degradation (>85%), and neomycin underwent significant degradation. Amoxicillin, oxytetracycline, and colistin displayed considerable degradation in both solution types but were more stable in ultrapure water solutions. The stability of cefotaxime and enrofloxacin in ultrapure water solutions and in the medium was very similar when compared; however, 3.6% of the former and 88.7% of the latter remained detectable by day 12. These findings are crucial for minimum inhibitory concentration (MIC) assessments, especially in minimum bactericidal concentration (MBC) studies, and in experiments concerning long-term evolution and co-selection. This study underscores the necessity of stability assessments in culture media to validate future experimental outcomes.

Exploring tradeoffs in southeast United States marine fisheries management using management strategy evaluation

Recreational fishing is the fastest growing sector in industrialized nations and can have substantial impacts on marine fish populations and ecosystems. Commercial objectives are typically characterized by maximizing yield and fishery stability whereas recreational anglers generally prefer sustained access to fishing and the availability of larger fish. Achieving these objectives while balancing tradeoffs between recreational and commercial fishing is essential to effective recreational and mixed-use fisheries management. Balancing multiple sector objectives is of particular concern in the southeast United States (US), where recreational fishing is the dominant source of mortality for marine fish stocks. We developed and applied a size-structured management strategy evaluation (MSE) tool, individually, to two stocks in southeast US Atlantic waters, black sea bass (Centropristis striata), a sedentary reef fish in overfished condition, and cobia (Rachycentron canadum), a migratory coastal pelagic fish, to evaluate the performance and tradeoffs of mixed management procedures against a variety of objectives. Several recreational and commercial objectives were aligned: fishers sought to conserve the stock and maximize catch, which simplified the evaluation of tradeoffs. We tested management procedures over alternate states of recruitment for black sea bass, and natural mortality for cobia. Management procedures that allowed harvest for black sea bass resulted in or risked an overfished status if the current weak recruitment regime continues, but could rebuild with no fishing regardless of recruitment state. Although results were sensitive to uncertainty in recruitment, no management procedures could achieve historic landings for either sector, and only management procedures that reduced effort consistently resulted in a reduced number of dead discards. No management procedures resulted in an overfished status for cobia. Management procedures for cobia generally achieved objectives and were robust to uncertainty in natural mortality. In both case studies, tradeoffs occurred between maximizing catch and season length and maintaining a stronger size structure in the population. This study resulted in a flexible MSE tool with strong potential utility for scoping management procedures that explicitly consider recreational fishing objectives.

The Long-Term Dynamics of Walleye Pollock Stocks in Relation to Oceanographic Changes in the East Sea

The decline in walleye pollock (Gadus chalcogrammus) stocks in Korean waters is a major concern for fishery conservation and management. However, the causes and mechanisms of this collapse remain unclear. This study investigated the complex dynamics influencing the abundance of walleye pollocks in the East Sea of Korea over several decades, by analyzing data from long-term changes in biological factors including composition of length and sex, catch, and oceanographic condition. Prior to the mid-1980s, the catch ratio of juveniles was higher than that of adults, with a higher proportion of females in both juvenile and adult catches compared to males. Especially, high fishing pressure on female individuals can be an important factor contributing to declining reproduction. Consequently, after the mid-1980s, there was a sudden decline in juvenile pollock catches. In the late 1980s, there was a rapid increase in sea surface temperature (SST) in the spawning grounds, resulting in a decrease in both the duration of suitable temperature for spawning and the regional proportion for suitable spawning conditions. Consequently, the decline in pollock stocks after the late 1980s due to overfishing of pollock in the mid-1980s was further exacerbated by the effects of SST warming after the late 1980s. These findings highlight the impact of overfishing and environmental factors on pollock stocks and indicate the need for appropriate fishery management practices to ensure the sustainable use of fishery resources.

Adapting service crop termination strategy in viticulture to increase soil ecosystem functions and limit competition with grapevine

Soil management and particularly service crops are a promising solution for addressing current challenges in viticulture as they limit the use of herbicides while increasing potential ecosystem services. Scientific literature barely considers the importance of service crop management to reach trade-offs between ecosystem services and disservices. This study evaluates during a three-year experiment, 6 service crop termination strategies for winter service crops, combining two service crops termination periods (early termination in February vs. termination at grapevine budburst) and three termination methods (mower (M), mower + tillage (T), roller-crimper (R)). Service crop (biomass, C:N ratio, weeds, and mulch following termination), soil ( soil organic matter, microbial biomass, and water and nitrogen stocks), and grapevines (predawn leaf water potential, yield components, δ13C, yeast assimilable nitrogen in juice, and pruning weight) were monitored from 2019 to 2022. Allowing service crops to develop until the budburst of the vine resulted in a two to three-fold increase in biomass compared to early destruction. Termination involving soil tillage was the most effective method, as treatments destroyed early with soil tillage exhibited almost no regrowth. Soil tillage termination led to the lowest biomass of weeds at the grapevine flowering two years out of three, and prevented the regrowth of certain sown plants, especially Poaceae. The roller was less effective in destroying service crop species but was the best method for maintaining plant residues on the soil surface. A higher soil microbial biomass was observed with termination at budburst, combined with no-till termination methods. Termination involving soil tillage was notably more effective in stopping service crop transpiration, increasing soil water stocks and improving grapevine water status. In 2020 and 2022, soil inorganic nitrogen stocks were almost 4 times higher in the T treatments compared to the other two termination methods, achieving a level of approximately 61 kg ha−1 that closely corresponds to the annual nitrogen requirements of grapevines. The yeast-assimilable nitrogen (YAN) content in grape juice mirrored this trend. Pruning weight varied significantly between different termination methods, with T treatments exhibiting a higher pruning weight per vine in comparison to R and M treatments. In general terms, the T treatment had a significantly higher number of bunches, the M treatment had the lowest, and the R treatment exhibited intermediate values. Overall, the average grapevine yield ranged from 7.25 to 13.7 t ha−1, corresponding to 52–98 hL ha−1 (with 4000 vines ha−1, 140 kg hL−1). This level of production may be accepted for Protected Designations of Origin that limit grapevine yield to 40 or 60 hL ha−1, but it could be a limitation for Protected Geographical Indications, which permit 90 hL ha−1, or unlabeled productions without yield limitations. Given the Mediterranean climate context, with rising frequencies of dry winters due to climate change, termination involving soil tillage appears to be the least risky strategy to preserve grapevine vigor and production while improving soil-based ecosystem functions. However, this might be contingent on the targeted yield and wine valuation.

WATER SECURITY IN THE KYRGYZ REPUBLIC: POST-SOVIET CHALLENGES AND REGIONAL DYNAMICS

The article describes the features of the use of water resources of the Kyrgyz Republic after the collapse of the USSR in 1991. Water security, stocks and potential of water resources are considered. At the same time, examples show the importance of water resources in the economy and politics of the Kyrgyz Republic, relations with the states of Central Asia. An analysis of tensions with neighboring countries on water resources was carried out. The importance, benefits and potential problems of the CASA-1000 project are also analyzed. The article describes the legal regulation of water resources in the Kyrgyz Republic, economic benefits and role in international relations.

Evaluation of the Effects of Drip Irrigation and Fertigation scheduling on Tomato Yield under Polyhouse

In Northwestern Himalayas, there is scarcity of water owing to rugged terrain which results in lower tomato yield. Therefore to enhance the productivity of tomato, the experiment was conducted to evaluate the effects of drip irrigation and nutrient schedules on soil water dynamics and productivity of tomato under polyhouse. The treatments consisted of three drip irrigation levels viz., I1 (Daily drip irrigation 2.0 litre/m2 once in a day during first two months and 4.0 litre/m2 thereafter), I2 (Daily drip irrigation 1.0 litre/m2 once in a day during first two months and 2.0 litre/m2 thereafter) and I3 (Daily drip irrigation twice a day with 6 hours interval at 1.0 litre/m2) and three nutrient schedules viz., NPK75 (75% of RDF, 25% applied as basal and 75% through fertigation at 15 days interval), NPK100 (100% of RDF, 25% applied as basal and 75% through fertigation at 7 days interval) and NPK150 (150% of RDF, 25% applied as basal and 75% through fertigation twice a week). The results showed that the soil moisture content and soil water stock was higher under I3 and I1 and lower under I2 treatments. The marketable yield (6.31 kg m-2), water use efficiency (WUE) (1.94 g m-2 mm-1) and NPK uptake was significantly higher in I2 than I1 and I3. Among nutrient schedules, marketable yield (6.53 kg m-2), WUE (1.94 g m-2 mm-1) and NPK uptake were significantly higher under NPK150 nutrient schedule than NPK100 and NPK75. The net returns (Rs. 230) and benefit:cost (B:C) (4.62) ratio was highest under I2NPK150 followed by I1NPK150 and lowest under I3NPK75. The study concluded that I2 (Daily drip irrigation 1.0 litre/m2 once in a day during first two months and 2.0 litre/m2 thereafter) and NPK150 (150% of RDF, 25% applied as basal and 75% through fertigation twice a week) was most remunerative combination due to higher marketable yield and water use efficiency under polyhouse.

Carbon stock of mangrove ecosystem and role blue economy in Pangandaran West Java

The mangrove ecosystem is a forest area that grows in coastal areas and is located at a distance of 200 meters from the shoreline. Mangroves are one of the blue-carbon ecosystems that can absorb CO2 through the process of photosynthesis and store carbon in the form of biomass in the soil. Mangroves are the second largest store of carbon stocks in waters after coral reefs. The availability of mangrove ecosystem carbon stock data is very important as a baseline in the greenhouse data inventory from blue carbon ecosystems. Blue carbon can be used as a reference for the welfare of coastal communities commonly called the blue economy, the blue economy focuses on generating economic growth from the fisheries and marine sector in Indonesia. Marine ecosystems are also impacted by climate change. Based on data from WWF's Living Blue Planet Report 2015, the number of marine populations decreased by 49% in the period 1970- 2012. The data is closely related to the sustainable economic growth of the marine fisheries sector, in this case, the mangrove ecosystem. Analysis of mangrove ecosystems using circle plots carried out measurements of tree diameter and length and identification of tree species according to predetermined subplots then analyzed the amount of carbon stock using the Allometric Equation Model. The result obtained is that 80% of mangrove habitat conditions are still very good so they can contribute to producing a total stored carbon stock (blue carbon) of 55.98 tons/ha this can be an ecosystem service for the surrounding community that can increase the blue economy in the Pangandaran area of West Java.

Exploring the antimicrobial potential of chitosan nanoparticles: synthesis, characterization and impact on Pseudomonas aeruginosa virulence factors.

The escalating antibiotic resistance observed in bacteria poses a significant threat to society, with the global prevalence of resistant strains of Pseudomonas aeruginosa on the rise. Addressing this challenge necessitates exploring strategies that would complement existing antimicrobial agents, e.g. by substances mitigating bacterial virulence without eliciting selective pressure for resistance emergence. In this respect, free-form chitosan has demonstrated promising efficacy, prompting our investigation into reinforcing its effects through nanoparticle formulations. Our study focuses on the preparation of chitosan nanoparticles under suitable conditions while emphasizing the challenges associated with stability that can affect biological activity. These challenges are mitigated by introducing quaternized chitosan, which ensures colloidal stability in the culture media. Our approach led to the production of trimethylchitosan nanoparticles with a median size of 103 nm, circularity of 0.967, and a charge of 14.9 ± 3.1 mV, stable within a one-month period in a water stock solution, showing promising attributes for further valorization. Furthermore, the study delves into the antimicrobial activity of trimethylchitosan nanoparticles on Pseudomonas aeruginosa and confirms the benefits of both nanoformulation and modification of chitosan, as our prepared nanoparticles inhibit 50% of the bacterial population at concentration ≥160 mg L-1 within tested strains. Additionally, we identified a concentration of 5 mg L-1 that no longer impedes bacterial growth, allowing reliable verification of the effect of the prepared nanoparticles on Pseudomonas aeruginosa virulence factors, including motility, protease activity, hemolytic activity, rhamnolipids, pyocyanin, and biofilm production. Although trimethylchitosan nanoparticles exhibit promise as an effective antibiofilm agent (reducing biofilm development by 50% at concentrations ranging from 80 to 160 mg L-1) their impact on virulence manifestation is likely not directly associated with quorum sensing. Instead, it can probably be attributed to non-specific interactions with the bacterial surface. This exploration provides valuable insights into the potential of quaternized chitosan nanoparticles in addressing Pseudomonas aeruginosa infections and underscores the multifaceted nature of their antimicrobial effects.

Dynamic Analysis of Watershed Management and Sustainable Agriculture in Dryland Regions: A Case Study of Purulia District, West Bengal

Watershed management deals with managing groundwater and drinking water in dryland areas. In this study, a dynamic optimisation model for sustainable agriculture and watershed management is developed, which can help farmers in dryland regions maximise their profit from agricultural production. The steady-state values of water stock, profit and allocation of land between highly water-intensive and less water-intensive crops are determined. This study also carries out sensitivity analysis by perturbing various parameters such as technologies used in crop production, discount rate and annual recharge of groundwater stock. The results show that as the technology used for less water-intensive crops improves, groundwater stock and profit increase. This study captures how upstream and downstream farmers can optimise their net benefit from agriculture when there is water conflict between them. It also demonstrates how their water extraction patterns and benefits can change in the presence and absence of a social planner.

Population Dynamics and Stock Assessment of Atlantic Horse Mackerel (Trachurus trachurus) Stocks in the Western Egyptian Mediterranean Waters

Population Dynamics and Stock Assessment of Atlantic Horse Mackerel (Trachurus trachurus) Stocks in the Western Egyptian Mediterranean Waters

A time-varying Granger causality analysis between water stock and green stocks using novel approaches

This study examined the Granger-causality between global water stock and global green stocks (MSCI global environmental index, global alternative energy index, global pollution prevention index and global green building index) using a battery of innovative causality methods with available daily data covering 23rd June 2009 to 23rd June 2022. Empirical results reveal many episodes of causality between global water stock and each of the global green stocks during the study period, including the post-global financial crisis and COVID-19 periods. The Granger-causality between the stocks was also noticed at different market periods and frequencies. Thus, the results confirmed the water-energy nexus and water-environment nexus. These results informed some policy recommendations to ensure sustainable economic development.

CORRELATION OF WATER QUALITY FACTORS AND STOCK DENSITY TO GLUCOSE AND CORTISOL LEVELS IN CANTANG GROUPER (EPINEPHELUS FUSCOGUTTATUS X EPINEPHELUS LANCEOLATUS) RAISED IN CONVENTIONAL PONDS

The purpose of this study was to find a correlation between density and water quality with glucose and cortisol levels in Cantang grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus) reared in ponds as an indicator of stress. This study uses a time series sampling method in its implementation. There were 10 Cantang grouper samples taken in this study per pond with sizes ranging from 20-30 cm. Fish samples were taken from 3 different ponds so that a total of 30 cantang grouper samples were found, while 1.5 L of water samples were taken from each pond. The results of measuring glucose levels showed that the highest average glucose levels in fish blood were obtained in pond number 6 (51.22 ± 14.9 mg dl-1) while the lowest was in pool number 5 (40.95 ± 15.2 mg dl-1). Similar to glucose levels, the results of blood cortisol measurements showed that the highest average cortisol levels in fish blood were obtained in pond number 6 (116.45 ± 5.49 ng ml-1) while the lowest was in pool number 5 (112.64 ± 4.55 ng ml-1). Based on the results of the regression analysis between the variables of water quality factors and stocking density on glucose levels (Figure 1), an R-value of 0.729 is obtained, which means that there is a 72.9% relationship between the variables of water quality factors and stocking density on glucose (moderate relationship). While the results of the regression analysis between the variables of water quality factors and stocking density on cortisol levels (Figure 2), an R-value of 0.722 was obtained, which means that there is a 72.2% relationship between the variables of water quality factors and stocking density on cortisol (moderate relationship). According to this research study, water quality factors that had a significant effect (p>0.05) on glucose levels in Cantang grouper were Temperature, DO, Salinity and Ammonia.

Etlik Piliçlerde Sıcak İklimde Soğuk Su ve Yerleşim Sıklığının Oksidatif Metabolizmaya Etkisi

The present experiment was conducted to investigate the effect of drinking water temperature and stocking density (SD) on oxidative metabolism in the heart, liver, bursa fabricius, and thymus in broiler chickens raised under heat stress. The experiment comprised of 360 one-day-old Ross 308 male broiler chickens randomly divided to 6 experimental groups with 4 replicates in each group. Experimental treatments included three different SD (low = 12 birds/m2, medium = 15 birds/m2 or high = 18 birds/m2) and two different drinking water temperature (10oC or 31oC) in a 3 x 2 factorial arrangement. At the end of the experiment (42 days of age), two birds per replicate were euthanized for sample collection. The results indicated high SD increased oxidative damage and caused an increase in MDA formation in the heart, liver and thymus. On the other hand, cold water ameliorated the oxidative damage due to the high SD in the thymus. In the study, the statistically non-significant interaction was generally determined between cage stocking density and cold drinking water on the antioxidant system. Besides, while cold water administration increased CAT activity in heart and thymus tissues, decreased GSH activity. In conclusion, drinking water temperature and stocking density are key environmental factors effecting oxidative metabolism when broilers under high temperature conditions; however, more studies are needed in terms of the interactive effects of water temperature and stocking density on antioxidant enzymes under current conditions.

Responding to the global challenges of ‘Too Much, Too Little and Too Dirty’ Water: Towards a Safer and More Just Water Future

The world water crisis is manifest through ‘Too Much, Too Little and Too Dirty’ water at multiple scales from the local to the global. Understanding the key drivers and consequences of this water crisis, and who bears the biggest costs, is necessary to develop appropriate responses, at scale and over time. Using four framings: one, water stocks and limits; two, water rights and responsibilities; three, water values and prices; and four, green and grey water infrastructure, we review the challenges and possible responses. Using a water justice lens, we highlight the transitional and transformational pathways towards a safer and more just water future.

აკვაკულტურის განვითარების როლი საქართველოს სამცხე-ჯავახეთის რეგიონის ეკონომიკის ზრდის საქმეში

The article presents the analytical description of the current situation of aquaculture development in Samtskhe-Javakheti region and in Georgia in general. The data about sector development natural potential are provided, the indicators of the fish production dynamics are analyzed in the paper. Water resources have a great potential and their ecological-sound use enables Georgia to meet not only an internal demand of the country on the fresh water fish, but also due to specifics of the local waters, produce export product. Internal water resource of fresh water for fishery production includes total water surface of 16,900 ha of 860 lakes. Samtskhe-Javakheti region is distinguished with the specific water resources compared to other regions. The regions is rich with the hydro-resources, including the R. Mtkvari water-collecting basin, the basin of the rivers Uraveli, Paravani, Borjomistskali and Gujaretistskali with total size 6,250 m2, with the total water resource of 3, 475 mln m3. The region territory covers 15 non-drying, 25 drying and 64 little lakes, 5 water reservoirs transforming into the swamp of the hydro-resource objects. The total size of the basin of the main lake exceeds 983 m2, the volume of the water reaches to 400 million m3. The water reservoir located in the Lirbalakhi basin in the region includes 2.08 million m3, and the size of the swamps is 817 ha in the region. The article studies the dynamics of the land plots occupied by aquaculture. According to the data, there is 23% of growth of the land plots occupied by aquaculture in entire Georgia; while the situation is different in the target region, there is 10% of reduction, followed by reduction of the share of aquaculture land from 11.1% until 10.6%. Study of the aquaculture fodder supply demonstrated that use of combined fodder is increasing in Georgia; average rate of the growth consists of 5-7 % in the country, while the rate is higher in Samtskhe-Javakheti region, where use of combined fodder achieved 35% of growth. There is tendency of growth in use of all kind of fodder. The index of the fodder expenses reached 1.30 throughout entire country, while it is 1.38 in Samtskhe-Javakheti, indicating strengthening of the fodder basis and intensive development of the field. The analysis of fish production dynamics is also an indicator for the further development of the aquaculture. In 2021 compared to 2019, there is 16% of growth in production of the fish, comprising 2,861 tons. The growth achieved 24% in the same period in the region what can be considered as a positive phenomenon in fishery production in Georgia, where the share of the fish farms (family-run) was increased up to 60% with growing engagement of the farmers aged 25-45 from 20% up to 29%. The rate of fish production is in compliance with the increased rate of water stock. The study revealed the specific problems (fish structure, diversification of the fodder, veterinarian service, growing of young fish) requiring solution to increase development of fresh water fish breeding, making financial sustainability of farming and economic growth of the region.

The Effect of Drinking Water Temperature and Stocking Density on Broiler Performance, Meat Quality and Some Behavioral Traits at High Ambient Temperature

The present study examined the effect of drinking water temperature and stocking density on performance (cumulative body weight gain, feed intake, and feed conversion ratio), meat quality, and behaviour traits (eating, drinking, lying, standing, and dust bathing) in broilers. A total of 360 broiler chicks (Ross 308) were randomly divided into 6 experimental groups, in a 2x3 factorial arrangement of drinking water temperature (10°C or 31°C), with stocking density (12, 15 or 18 birds/m2), each consisting of 4 replicate pens. Meat quality traits (pH15, L*, CL, and WHC), lying and standing behaviours were affected by water temperature. The stocking density significantly affected the cumulative body weight gain, feed intake, feed conversion ratio, color of breast meat [lightness (L*), redness (a*), yellowness (b*)] of broiler chickens. In conclusion, management practices such as stocking density and drinking water temperature in broilers could reduce the detrimental effects of high ambient temperature on growth performance, meat quality traits, and behaviour.

What drives the recruitment of European sardine in Atlanto-Iberian waters (SW Europe)? Insights from a 22-year analysis

The European sardine (Sardina pilchardus) is the most abundant and socio-economically important small pelagic fish species in Western Iberia Upwelling Ecosystem. As a result of a long series of low recruitments, sardine biomass off Western Iberia has greatly reduced since the 2000s. Recruitment of small pelagic fish is mainly dependent on environmental factors. In order to identify the key drivers of sardine recruitment, it is essential to understand its temporal and spatial variability. To achieve this goal, a comprehensive suite of atmospheric, oceanographic, and biological variables spanning 1998–2020 (22 years) were extracted from satellite datasets. These were then related to in situ recruitment estimates obtained from yearly spring acoustic surveys carried out along two different hotspots of sardine recruitment of the southern Iberian sardine stock (NW Portugal and Gulf of Cadiz). Sardine recruitment in Atlanto-Iberian waters appears to be driven by distinct combinations of environmental factors, although sea surface temperature was identified as the main driver in both regions. Physical conditions that favour larval feeding and retention, such as shallower mixed layers and onshore transport, were also seen to play a vital role in modulating sardine recruitment. Furthermore, high sardine recruitment in NW Iberia was associated with optimal conditions in the winter (January–February). In contrast, recruitment strength of sardine off the Gulf of Cadiz were associated with the optimal conditions during late autumn and spring. The results from this work provide valuable insights to further understand the dynamics of sardine off Iberia, with potential to contribute to the sustainable management of sardine stocks in Atlanto-Iberian waters, particularly under climate change.