Aquaculture International最新文献

Development programs have intensified support for the aquaculture sector to improve production and productivity, as well as food security and diet quality for smallholder farmers. This paper examines the impact of farmers’ participation in Common Interest Groups (CIGs) and the effects of aquaculture development support programs on the net returns and productivity of tilapia fish in Kenya. The study used household-level data of 506 members of the CIG who were randomly selected for the treatment group and benefited from Aquaculture Business Development Program (ABDP) interventions. The analysis employed an endogenous switching regression model to account for selection bias. The results reveal that membership in CIGs and receiving fish production interventions have resulted in a 32.3% increase in tilapia fish sales returns and a 6.6% increase in tilapia fish yields. Specifically, ABDP interventions are aimed at providing fish producers with ponds and cages had a significant and beneficial effect on fish yields and income returns. This finding suggests that policies with targeted interventions that support aquaculture infrastructure can play a significant role in increasing the incomes of smallholder farmers and reducing rural poverty in Kenya.

To investigate the effects of composite lactic acid bacteria (LAB) on the growth performance, intestinal physiology, and non-specific immunity of sea cucumbers, experiments were conducted using sea cucumbers with an average body weight of 2.43 ± 0.02 g. Five experimental groups were designed, with 3 replicates per group and 20 sea cucumbers per replicate. The sea cucumbers were fed with feed containing different concentrations of composite LAB (0%—Control, 0.5%, 1%, 1.5%, and 2%) for 56 days. The findings demonstrated a significant enhancement in the body weight gain (BWG) and specific growth rate (SGR) of the sea cucumber upon supplementation with the composite LAB. The activity of digestive enzymes in each experimental group was significantly higher than that in the control group. The activities of superoxide dismutase (SOD), lysozyme (LZM), catalase (CAT), total antioxidant capacity (T-AOC), acid phosphatase (ACP), alkaline phosphatase (AKP), and polyphenol oxidase (PPO) in each experimental group were all significantly higher than those in the control group. Among them, the activities of SOD, LZM, T-AOC, and AKP increased with the increase in the amount of additive, while the activities of CAT and ACP peaked when the additive amount was 1.5%. The content of malonaldehyde (MDA) showed a continuous declining trend. The incorporation of the composite LAB into the feed resulted in a significant enhancement of intestinal villus height (I-VH) and intestinal villus width (I-VW) in sea cucumbers. The experimental groups exhibited elevated expression levels of immune and growth-related genes compared to the control group. The experimental results indicate that the addition of composite lactic acid bacteria in the feed has a positive effect on the growth performance, intestinal physiology, and immune indicators of sea cucumbers, with the best results observed at an additive level of 1.5%.

The purpose of this study was to investigate the effects of allicin on behavior, intestinal health, and behavioral resistance to handling stress in sea cucumbers in summer. Behavioral analysis found that 3% dietary allicin significantly improved crawling and feeding behaviors of sea cucumbers without affecting their food choices in summer. We used 16S rRNA gene sequencing to analyze the intestinal microbiota of sea cucumbers. Alpha diversity showed no significant difference between sea cucumbers fed with and without allicin. Bacteroidetes and Firmicutes were more abundant in the intestinal tract of sea cucumbers fed with allicin diet, with a fourfold increase in Firmicutes-to-Bacteroidetes ratio, compared to the diet without allicin. This indicates that allicin does not influence species diversity or richness of intestinal microorganisms, but changes the structure of the microorganisms. This study showed that crawling and feeding behaviors of sea cucumbers fed with allicin were significantly higher than those of sea cucumbers fed without allicin under air exposure. This is probably attributed to the decreased oxidative impacts of handling stress on sea cucumbers fed with dietary allicin. We provided a cost-effective method to improve crawling and feeding abilities, to regulate intestinal microbial colonies, and to enhance behavioral resistance to handling stresses in sea cucumbers in summer. We suggest aqua-farmers incorporate 3% allicin into feed to reduce harms caused by high temperature and handling stresses.

Impact of opportunistic bacterial pathogens and their antimicrobial resistance continues to increase in aquaculture, posing significant public health concerns. The present study aimed to investigate the incidence of mortality in cultured Nile tilapia, O. niloticus in Andhra Pradesh, India. Diseased samples exhibiting exophthalmia, swollen abdomen, hemorrhages and pale gills were collected to isolate pathogenic bacteria. The bacteria were characterized using cultural, biochemical characteristics and 16 S rRNA gene sequence. The isolate had 99.66% homology with Micrococcus luteus (GenBank accession no. PP659810). The cumulative mortality LD₅₀ was calculated as 1.39 × 10⁵ CFU per fish. Histopathological alterations revealed hyperplasia and fusion of gill lamellae, enlarged hepatocytes, degenerative renal tubules, fibrous lesions, ellipsoidal compression of white pulp, degeneration of splenic tissue, and melano-macrophage centres. Antibiogram studies revealed that M. luteus showed varying degrees of resistance to different antibiotics, with a multiple antibiotic resistance index of 0.62 ± 0.3. Mortality rate in cultured farm and experimental infection is 30% and 70%, respectively. These findings highlight that M. luteus can be considered as one of the potential bacterial pathogens in Nile tilapia. Our findings highlight that Good Aquaculture Practices (GAP), biosecurity, disease surveillance, and the One Health Approach are essential for tackling AMR- and disease-related issues. This report forms the first record of emergence of M. luteus infection in cultured Nile tilapia, O. niloticus in India.

In captivity, the physiological condition of mature brood fish has a vital role for a successful artificial spawning. Therefore, the current study aimed to minimize endocrine and metabolic disruptions during routine handling, transportation, and acclimatization during artificial spawning in L. ramada. Here, we determined the impacts of transportation and handling, as well as the acclimation to different salinities on the levels of total thyroxine (T4), triiodothyronine (T3), cortisol, and glucose in the mature L. ramada females. The transportation procedures of cultured mature females of L. ramada without anesthesia induced physiological stress as reflected with a rapid elevation in serum cortisol and glucose concomitant with a decrease in T4 within 3 h. However, the anesthesia protocol and the gradual acclimatization to seawater (24 h) were successful in maintaining baseline concentrations of the measured hormones in mature L. ramada females. The recorded levels of thyroid hormones (T4 and T3) and cortisol proved that 40 mg l⁻¹ of clove oil was superior to anesthetic tricaine methane sulfonate (MS-222). In parallel, clove oil as an anesthetic has a rapid induction time and longer recovery time compared to MS-222 in L. ramada anesthesia. So, the slow acclimation and clove oil anesthesia were crucial during the induction of spawning in L. ramada. Indeed, all injected females were physiologically stable and spawned within the appropriate time consistent with the histological observation of both ovary and liver. Together, these findings recommend that maintaining the physiological stability of broodstock is critical for the successful artificial spawning of mullet.

Immunostimulant phytogenic feed additives are given great concern for improving fish health, growth, immune responses, and resistance to diseases. This research investigated the impact of dietary propolis (PRO), turmeric (TUR), and their combination on the growth, hematology, antioxidant-immune responses, and their regulating genes in Nile tilapia (Oreochromis niloticus) during Edwardsiella tarda challenge. For 8 weeks, a total number of 320 fish (20.70 ± 0.14 g) were allocated into four groups at random, each with eight replicates (10 fish each). The first group (1st) was given the basal diet (control) without any supplements. The 2nd, 3rd, and 4th groups were supplemented with 1% PRO, 1% TUR, and the mixture (1%PRO + 1%TUR), respectively. The experimental groups were challenged intraperitoneally with E. tarda at a dose of 0.1 mL (1 × 10⁵ CFU) at the termination of the feeding trial, and the fish survival was estimated for an additional 7 days. The results demonstrated that fish-fed diets supplemented with PRO and/or TUR showed higher body weight, condition factor, specific growth rate, feed intake, and feed efficiency utilization than the control group (P < 0.05). The hematological, protein profile, and antioxidant-immune (total antioxidant capacity, lysozymes, and IgM) parameters were substantially improved in the challenged fish fed on PRO and/or TUR diets compared to the challenged non-fed fish. The lipid profile and malondialdehyde were substantially decreased in the challenged fish fed on PRO and/or TUR diets compared to the challenged non-fed group. Notably, a down-turning of nuclear factor kappa B (NFκB) and tumor necrosis factor-alpha (TNF-α) expression with up-turning of nuclear factor erythroid 2-related factor 2 (Nrf2) and transforming growth factor-beta (TGF-β) expression was noticed in the challenged fish fed on PRO and/or TUR diets compared to the challenged non-fed fish. Noteworthy, dietary PRO and/or TUR improved the fish survival during E. tarda challenge. The mixture of PRO and TUR can be added to Nile tilapia diets to enhance their growth, immune response, and resistance to E. tarda. These outcomes help in the sustainable development of the Nile tilapia culture industry.

Graphical Abstract

Triploid Pacific oyster Crassostrea gigas is increasingly important in aquaculture due to its improved growth and meat quality. However, adaptability differences between diploid and triploid oysters in varying environments are inconclusive. To address this concern, we compared the growth, physiological parameters (clearance rate, CR; oxygen consumption rate, OCR; ammonia excretion rate, AER; the Arrhenius break temperature (ABT) based on heart rate), and metabolism-related gene expression (HK, PK, and PEPCK) in diploid and triploid C. gigas at various temperatures (17 ℃, 20 ℃, 23 ℃, 26 ℃, and 29 ℃) and salinities (18 psu, 22 psu, 26 psu, 30 psu, and 34 psu). Triploids exhibited higher shell heights than diploids across various temperature and salinity treatments. No significant difference in CR, OCR, or AER was observed between diploids and triploids. Compared to diploids, triploids had higher O: N ratios at 29 ℃ but lower O: N ratios at 18 and 22 psu. Except for the 23–26 ℃ range, diploids had lower Q₁₀ values, suggesting that they are less sensitive to respiration changes within these temperature ranges. Additionally, triploids demonstrated higher thermal adaptation, as evidenced by a higher ABT value (triploids: 26.52 ℃ > diploids: 25.71 ℃). The PEPCK/PK and PEPCK/HK ratios indicated that triploids have lower anaerobic metabolism levels than diploids at 17 ℃, 23 ℃, and 26 ℃, but higher levels at salinities of 18 psu, 22 psu, and 26 psu. Overall, triploids showed greater adaptability at 17 ℃, 23 ℃, 26 ℃ and 29 ℃, while lower adaptability at salinities of 18 psu, 22 psu, and 26 psu. Our findings provide insights into the physiological metabolism underlying temperature and salinity adaptation in diploid and triploid oysters.

Studies are showing that albinism has negative effects on growth and immunity in rainbow trout, and there are also studies showing the opposite. Therefore, in this study, a comparison has been made between the albino (AA), normal pigmented (PP), mixtures (Mix), and their crossbreds (AP and PA) of rainbow trout in terms of growth performance, non-specific immune system parameters, mRNA relative expression levels, and disease resistance. Regarding the non-specific immune system parameters examined, the albino group (AA) showed the highest lysozyme, NBT, and IgM levels, while the normal pigmented (PP) group exhibited the lowest values. The lowest mortality rate was observed after the challenge test in the AA group (16%), followed by PA (30.66%), Mix (32.00%), and AP (36.00%), with the highest mortality rate recorded in the PP group (52.00%). The results obtained from experimental research have been confirmed through molecular analyses. The expression level of IL-8 showed the highest level in the AA group (6.05 ± 1.95^a), followed by PA (4.44 ± 1.60^ab), Mix (3.04 ± 0.72^bc), and AP (1.29 ± 0.23^c) groups compared to the PP group (onefold). There was no statistical difference among the groups regarding growth performance (except for specific growth rates and final weights) and IGF-1 mRNA expression levels. In conclusion, the study suggests that albinism does not have a detrimental effect on rainbow trout. In addition, the observation of a strong non-specific immune system in albinism could promote more efficient and sustainable aquaculture.

There is a growing interest in high-performance, sustainable, and efficient aeration technologies to ensure the necessary oxygen levels in ponds, wastewater treatment plants, and aquaculture areas. Multiple optimization efforts are mandatory to maximize the aeration performance and energy efficiency of high-aeration performance systems simultaneously. This study aims to optimize the aeration performance of aquaculture systems using the Taguchi-based gray relational analysis (GRA) method. Taguchi-based gray relational analysis method has been preferred due to its capability of enabling optimization with fewer experiments, analyzing interactions among independent variables, and its applicability in both linear and nonlinear systems. The use of the Taguchi-based GRA method to improve efficiency in the aeration process is a novel approach for these systems with multiple variables. In this study, the optimal parameter levels for the conduit aeration system were determined and compared with the initial levels through validation tests. Additionally, the effects of parameters on aeration performance and energy cost were analyzed. As a result, it was determined that the aeration performance of the system increased fourfold compared to the initial level, and the cost decreased sixfold. It was observed that the most effective parameter on the system is the gate opening, and the least effective parameter is the tank diameter.

In recent years, shrimp aquaculture has become one of the most promising and fastest-growing aquaculture industries in providing aquatic food globally. In comparison with other aquatic products, shrimp plays an important role because of its high export value and self-employment opportunities provided for farmers and stakeholders along its value chain in developing countries. This study attempts to provide some insights into the export-agricultural growth nexus by considering the aquaculture shrimp industry. The objective of this paper is to analyze the effects of shrimp exports on aquaculture shrimp production over the period 1998–2022 for the major South Asia and Southeast Asian shrimp-producing countries. By using the cointegration approach and panel autoregressive (PVAR) model, empirical findings indicated that there is no causal relationship between the volume of shrimp aquaculture production, its exports, imports, and the domestic prices in the long run and the short run. In addition, the results of the PVAR approach did not show enough evidence to support the assumption that growth in shrimp exports can enhance growth in the production of aquaculture shrimp perhaps because of the small sample size or other plausible reasons. However, our findings evidence that exports rather than imports explain much of the variation in aquaculture shrimp production across time. Despite the limitations of evidence, hence suggesting the need of more data, these findings have some policy implications in providing insights to the governments in countries where aquaculture (shrimp industry) have considerable importance. Exploring all possible ways to increase or promote aquaculture shrimp production can help shrimp producers in South Asia and Southeast Asia countries and, by extension, all shrimp production countries globally. Evaluating the shrimp exports-production growth nexus or similar work to this current study could be carried out by incorporating more countries and variables over a much longer period.