Offshore Cage Culture Research Articles

Exploring the underlying mechanisms of enteritis impact on golden pompano (Trachinotus ovatus) through multi-omics analysis

Enteritis posed a significant health challenge to golden pompano (Trachinotus ovatus) populations. In this research, a comprehensive multi-omics strategy was implemented to elucidate the pathogenesis of enteritis by comparing both healthy and affected golden pompano. Histologically, enteritis was characterized by villi adhesion and increased clustering after inflammation. Analysis of the intestinal microbiota revealed a significant increase (P < 0.05) in the abundance of specific bacterial strains, including Photobacterium and Salinivibrio, in diseased fish compared to the healthy group. Metabolomic analysis identified 5479 altered metabolites, with significant impacts on terpenoid and polyketide metabolism, as well as lipid metabolism (P < 0.05). Additionally, the concentrations of several compounds such as calcitetrol, vitamin D2, arachidonic acid, and linoleic acid were significantly reduced in the intestines of diseased fish post-enteritis (P < 0.05), with the detection of harmful substances such as Efonidipine. In transcriptomic profiling, enteritis induced 68 upregulated and 73 downregulated genes, predominantly affecting steroid hormone receptor activity (P < 0.05). KEGG pathway enrichment analysis highlighted upregulation of SQLE and CYP51 in steroidogenesis, while the HSV-1 associated MHC1 gene exhibited significant downregulation. Integration of multi-omics results suggested a potential pathogenic mechanism: enteritis may have resulted from concurrent infection of harmful bacteria, specifically Photobacterium and Salinivibrio, along with HSV-1. Efonidipine production within the intestinal tract may have blocked certain calcium ion channels, leading to downregulation of MHC1 gene expression and reduced extracellular immune recognition. Upregulation of SQLE and CYP51 genes stimulated steroid hormone synthesis within cells, which, upon binding to G protein-coupled receptors, influenced calcium ion transport, inhibited immune activation reactions, and further reduced intracellular synthesis of anti-inflammatory substances like arachidonic acid. Ultimately, this cascade led to inflammation progression, weakened intestinal peristalsis, and villi adhesion. This study utilized multi-level omics detection to investigate the pathological symptoms of enteritis and proposed a plausible pathogenic mechanism, providing innovative insights into enteritis verification and treatment in offshore cage culture of golden pompano.

욕지도 외해가두리 양식장의 참다랑어(Thunnus orientalis) 양식 사업성 비교분석

This study aimed to analyze the feasibility of T. orientalis offshore aquaculture production performance in Yokjido located in Tongyeong, Korea. Based on the collected biological, costs and market price data, the results indicated that under the same conditions of analyzing economic feasibility. At the social discount rate of 4.5% applied to public corporations and quasi-governmental organizations, 2,000 caught and imported T. orientalis were sold at a survival rate of 60%, respectively, at an individual weight of 30 kg to KRW 40,000/kg, thereby the financial feasibility of T. orientalis offshore cage culture was analyzed. The net present value (NPV) of caught bluefin tuna was 1,858,952 thousand won, and the corresponding internal rate of return (IRR) was 17.6%. In the case of imported, the net present value (NPV) was -1,157,227 thousand won, and the corresponding internal rate of return (IRR) was -4.2%. As a result of estimating the net present value (NPV) and internal rate of return (IRR) using the cash flows (including depreciation) generated for 10 years in units of the business period (1year). For the caught juvenile, NPV showed a positive value and IRR exceeded the social discount rate of 4.5%. On the other hand, in the case of imported, NPV had a negative value and IRR was less than 4.5% of the social discount rate. Therefore, it was found that there is a business possibility to cultivate T. orientalis with juvenile caught at the offshore farm in Yokjido has business potential.

Relationships between the Gut Microbiota of Juvenile Black Sea Bream (Acanthopagrus schlegelii) and Associated Environment Compartments in Different Habitats.

The fish-gut microbiota play a key role in the physiology, development, and fitness of its host. An understanding of fish-gut microbial communities and the factors influencing community composition is crucial for improving fish performance. In this study, we compared the gut microbiota of juvenile black sea bream Acanthopagrus schlegelii among habitats: (1) wild, (2) offshore cage-culture, and (3) pond-culture. We also explored the relationships between the gut microbiota and host-associated environmental factors. Gut samples and associated environmental compartments were investigated using 16S rRNA gene sequencing. Our results revealed significant habitat-specific differences among the gut microbiota of juvenile A. schlegelii. Wild populations of juvenile A. schlegelii had more diverse gut microbiota than populations cultured in pond habitats due to their omnivorous feeding habits and the corresponding abundance of natural food resources. Significant variations in the composition, core taxa, and diversity of the microbiota were also found between the gut and the environmental compartments. However, no significant differences were observed among the microbiota of the environmental compartments in the relatively isolated pond habitat. Source tracking analysis recovered connections between the fish-gut microbiota and the diet, water and sediment environmental compartments. This connection was especially strong between the microbiota of the fish gut and that of the diet in the pond habitat: the diet microbiota accounted for 33.48 ± 0.21% of the gut microbiota. Results suggested that all A. schlegelii shared a core gut microbiota, regardless of differences in diet and habitat. However, environmental factors associated with both diet and habitat contributed to the significant differences between the gut microbiota of fish living in different habitats. To the authors’ knowledge, this study presents the first comparison of gut microbiota among juvenile A. schlegelii with different diets and habitats. These findings enrich our understanding of the gut microbiota of A. schlegelii and help to clarify the interaction between gut microbiota and environmental factors. Our results may also help to guide and improve fish ecological fitness via the regulation of gut microbiota, thereby increasing the efficacy of stock enhancement programs for this species.

Storm damage risk assessment for offshore cage culture

This study establishes a practical methodology for storm damage risk assessment and zoning for offshore cage culture by superimposing the vulnerability theory onto hydrodynamic modeling. The peak significant wave height is statistically correlated to the normalized fatigue load criteria at specified loading cycles to classify the destruction duration and damage state during storm events. The yield damage of the flotation pipe under cyclical wave oscillations was identified as the major failure mechanism of the sea cage. The structural failure risk would significantly decrease to 4.5-m waves, which is much lower than the manufacturing standard due to cumulative damage in a relatively short operation time. The wave-circulation model was applied to hindcast 112 high-impact typhoon scenarios in the study area for the return period analysis of the storm wave field. The damage risk distribution of the cage culture was mapped across the landscape to increase storm strength according to the vulnerability classification. The effectiveness of island shielding was explicitly revealed, and the leeward side was overall less risky as the return period increased, with the safe area shrinking inshore. For extreme conditions over a 100-year return period, the shield performance of leeward bays varied significantly due to the shoreline profile differences. Some existing cage deployment locations are at-risk relative to the structural resistance capability, whereas other unrecognized areas might be suitable for cage culture. These findings imply the necessity of storm risk assessment before proactive prevention measures and deployment zoning. The methodology may also be adapted to storm risk predictions for other facilities in the coastal ocean.

Comparison for ecological economic performance of Chinese sea perch (Lateolabrax Maculatus) under different aquaculture systems

Chinese sea perch (Lateolabrax Maculatus) is one of the main marine fish culture species in China, its green development has received increasing attention and its ecological economic study is rare. Based on field survey, this paper takes water pollution tax of China as conversion indicator for aquaculture eutrophication to simulate aquaculture waste fee for further analyzing the ecological impact of Chinese sea perch's aquaculture. For data analysis, data envelopment analysis model has been used. The comparison for Chinese sea perch's economic performance and ecological economic performance under its main aquaculture systems has been done. The results show that: 1. The simulated waste fee has no significant impact for the comparison. 2. Ranking for ecological economic performance's ecological economic, technical and scale efficiency is as follow: pond farming, offshore cage culture and cage culture. 3. Offshore cage culture is the only system presenting positive increase for ecological economic performance, which makes its aquaculture activity more sustainable than other systems. 4. The key point of green development is to maximize the ecological economic efficiency of main aquaculture systems. Thus, offshore cage culture is the most sustainable aquaculture system among China's current marine fish culture systems, and other systems need innovation for achieving the green development of China's aquaculture.

Raising the Performance of Gilthead Seabream (Sparus aurata) Juvenile in Offshore Cage Culture

The growth parameters of gilthead seabream (Sparus aurata) fry supplied from three different hatcheries stocked in nine HDPE offshore cages (30 m diameter and 22 m depth) were investigated for 450 days. It was determined that the fish obtained from Firm A on the 450th day gained more weight by consuming less feed. Fishes belonging to Firm A consumed an average of 1.8 kg of feed for one kg body weight gain, while fishes belonging to Firm B consumed an average of 2.29 kg and fishes of Firm C consumed an average of 2.18 kg. However, feed conversion rates were not significant between firms. Also, the highest survival rate was determined in fish from Firm B with 96.11%. As a result, the success of fish culture should be guaranteed by the supply of high standard juvenile fish. Otherwise, production costs and fish quality will be adversely affected.

Improvement of gonad quality of the sea urchin Mesocentrotus nudus fed the kelp Saccharina japonica during offshore cage culture

In northern Japan, Saccharina kelps are natural diets for sea urchins and are known to enhance sea urchin gonad size. However, little is known about the effects of the kelp diet on gonad quality and consistency among individuals. In the present study, Mesocentrotus nudus adults collected from a barren were cultured in a suspended cage from late February to early June 2014 in Shizugawa Bay, Miyagi Prefecture. They were fed stipes of Undaria pinnatifida for 56 d followed by fresh Saccharina japonica kelp for 42d. At the end of the culture period, gonad indices, gonad hardness, gonad color (L* (lightness), a* (redness), b* (yellowness)), free amino acid (FAA) contents in the gonads, and sensory qualities of the cultured sea urchins (EC) were measured and compared to those of the natural population from the barren (EB) and those from the Eisenia bicyclis kelp bed (EK) in the bay. Gonad index and L* values of EC urchins were higher than those of urchins from the barren at the start of culture (SCB). Total color (L*, a*, b*) of the gonads of EC and EK urchins were similar. Gonad hardness of EC and EK urchins was similar and lower than that of EB urchins, and the coefficients of variation of gonad index, color, and hardness were lower than those from the barren (SCB and EB). Sweet tasting alanine contents of the gonads of EC urchins were markedly higher than those of the gonads from the other urchin specimens. Bitter tasting FAA contents of the EC urchin gonads were higher than those of EK and EB urchins, although arginine and lysine contents were lower than those of EB urchins. Sensory scores of overall taste of EC urchins were higher than those of EB urchins and similar to EK urchins, possibly due to the increased alanine content. These results suggest that gonad size, color, hardness, taste, and consistency among individuals of M. nudus collected from barrens can be improved to reach levels similar to those of urchins from the E. bicyclis kelp bed by cage culture with short-term feeding of Saccharina kelps. Changes in gonad qualities seemed to be mainly due to S. japonica as the food source because hard U. pinnatifida stipes were rarely eaten and had markedly low protein content. Extension of cage culture duration with S. japonica feeding from spring to summer would increase gonad size and further improve gonad quality.

외해 가두리 대구 양식업 경제적 타당성 분석

외해 가두리 대구 양식업 경제적 타당성 분석

The Efficacy of Inactivated Photobacterium damselae subsp. piscicida Combined with Levan/Alum as Vaccine against Photobacteriosis in Cobia, Rachycentron canadum

AbstractPhotobacterium damselae subsp. piscicida (Phdp) is a major pathogen of cultured cobia (Rachycentron canadum), a primary target species for offshore cage culture in Taiwan. Serum antibody titers as well as efficiency and duration of protection against Phdp were evaluated following intraperitoneal administration of a candidate vaccine prepared with formalin‐inactivated whole cells in combination with levan/alum adjuvants. The results showed vaccinates delayed the disease onset and had significantly (P &lt; 0.05) less mortality than control nonvaccinates during Days 21–105 postvaccination with highest relative percentage of survival (RPS) and antibody titer up to 81.4% and 1:614, respectively. There was a highly significant positive linear correlation between the RPS and antibody titer (R2 = 0.841). Long‐lasting and significant protection against Phdp can be achieved with inactivated Phdp plus levan/alum, a potential cobia vaccine against photobacteriosis. Levan/alum complex may represent a promising adjuvant formula for the development of a Phdp vaccine.

Identification of Microsatellite DNA Markers for Pacific Threadfin Parentage Assignment

Pacific threadfin, Polydactylus sexfilis, a highly desirable food fish in Hawaii, has been raised by offshore-cage culture in a large scale. To develop an effective genetic tool to monitor the broodstock resources and their mating patterns, we identified microsatellite loci of Pacific threadfin. Genotyping and analysis of 10 microsatellite loci in the wild and captive broodstock populations did not indicate significant differences among these populations. Five polymorphic microsatellite loci were further selected for the development of a parentage assignment test. Parental assignment analysis of one broodstock population showed that 90% of the offspring from three consecutive spawning events were successfully assigned to their specific parent-pairs. These five microsatellite loci provide an accurate and cost-effective method to assess the genetic variability and mating patterns in Pacific threadfin.

Tendances pour la pisciculture européenne de demain: cages au large, systèmes en eau recirculée et systèmes intégrés

Over the last few decades, European fish culture was developed mainly as a intensive monospecific activity. In most countries, marine aquaculture cannot continue to develop on the shore line where it first settled due to high competition with other activities. It has now to move either offshore or into recirculation systems located in less occupied spaces. Fresh water availability and impact of fish production farms on the environment are strongly restraining the development of the activity, which is even declining in some countries such as France. Recirculation systems make it possible to decrease water consumption and facilitate waste treatment. Their economical feasibility is being demonstrated and they offer an alternative to developing fish farms. Whatever the rearing system, nutrients of feed are partially converted into fish flesh and most of them are thrown back as wastes into the environment. Integrated systems make it possible to convert such nutrients into algae, molluscs or fish and to release purified water. This article presents some aspects of the development of three types of rearing systems which are increasingly used in northern Europe: offshore cage culture, recirculation systems and integrated systems.

Comparison between some procedures for monitoring offshore cage culture in western Mediterranean Sea: Sampling methods and impact indicators in soft substrata

Two sampling methods, an array of physical–chemical and biological indicators, and uni-multivariate statistical procedures were compared on the basis of sensitivity to detect any impact and cost-effectiveness criteria, applied to environmental monitoring of fish farming. Sampling was conducted in a western Mediterranean gilthead seabream ( Sparus aurata) and meagre ( Argyrosomus regius) farm (San Pedro del Pinatar, SE Spain). Both sampling methods (Van Veen grab vs SCUBA diving) provided similar results for all the parameters except redox potential. The most sensitive chemical parameters of the sediment were total phosphorus, total ammonium nitrogen and acid volatile sulphide, but the latter was the only one which correlated with the macrobenthic community structure. The application of univariate methods to biological indicators only showed a clear trend in two (AMBI and BENTIX) of the five indices used. Both biotic indices, although statistically correlated with the spatial pattern of the macrobenthic community, provided different quality status categorization that could lead to misinterpretation and so, validation in offshore conditions is required. Nevertheless, multivariate analysis of macrofauna confirmed a noticeable spatial pattern, at the same time that this statistical strategy has been proven and validated in a wide range of marine community studies.

Growth and survival of juvenile cobia, Rachycentron canadum, at different salinities in a recirculating aquaculture system

Cobia ( Rachycentron canadum) is an emerging aquaculture candidate for both offshore cage culture and land-based systems such as recirculating aquaculture systems. The ability to grow cobia at salinities other than oceanic (∼34 ppt) could present culturists with additional production opportunities with this species. Culture at low salinities could also reduce the incidence of disease and simplify water management. In two trials of 8 weeks each, this study investigated growth and survival of juvenile cobia reared at salinities of 5, 15, and 30 ppt. The trials were conducted in 456-L tanks, with 10 fish per tank. Water temperature was maintained at 27 ± 1 °C and dechlorinated municipal tap water (0 ppt, 56.8 ppm Ca 2+) was added to seawater (30 ppt, 325.3 ppm Ca 2+) in order to achieve treatment salinities. Early juveniles were used in both trials with average initial weights of 6.0 g for the first trial and 6.7 g for the second trial. During both trials, fish were fed to satiation twice daily with a diet prepared on site, and the amount fed was measured to determine feed efficiency. Fish from each tank were counted and weighed collectively each week until the end of each of the 8-week trials to monitor growth and survival. Survival among treatments was not significantly different in the first trial, but in the second trial survival was significantly lower in the 5 ppt treatment (68.3%) than in the 15 (90%) or the 30 ppt (92.5%) treatments. Feed efficiency was extremely high in both trials with all treatments ranging between 1.05 and 1.13. Fish reared at a salinity of 5 ppt grew as well or better than the fish reared at salinities of 15 and 30 ppt (mean weight gained, 96.2–115.3 g). This study indicates that culture of cobia juveniles may be practical in salinities as low as 5 ppt.

On the calculation of wave climate for offshore cage culture site selection: a case study in Tenerife (Canary Islands)

The lack of suitable sheltered sites is forcing fish farmers to move to more exposed offshore locations in order to provide for continued growth in the industry. However, as farmers move to more exposed sites for ongrowing, extreme weather conditions must be regarded as a normal environmental condition. For appropriate cage system selection and siting sufficient wave data has to be available, as wave action (wave climate) on floating cage structures may create conditions where failures are likely. At present, there are many methods of estimating wave climate, but none has been clearly presented for its use in offshore cage culture siting, particularly in a format that may be used within an integrated selection tool. This paper presents a novel methodology for wave climate characterisation in offshore fish cage site selection, based on a case study for sitting offshore seabass and seabream cages in Tenerife (Canary Islands). The mid-term statistic was used to identify prevailing wave heights and the long-term statistic or extreme wave analysis was used to identify the likely highest waves over a certain time period (15 years). The former can promote gradual failure of structures, while the latter may cause instant total failure. Based on this information, three cage systems were selected and, a suitability map was created for each using Geographical information systems, showing the more suitable zones to site the cages.

Economics of cage culture in Puerto Rico

Puerto Rico has been faced with a decline of fish stocks similar to other parts of the world. Offshore cage aquaculture might be an answer to this problem although there are many unanswered questions. This paper describes a project in Puerto Rico that assessed the economics of offshore cage culture for aquaculture. The first cage was placed in the water in February 2002 with a second one to follow shortly thereafter.

Optimal dietary protein and lipid levels for juvenile cobia ( Rachycentron canadum)

Two growth trials were conducted to investigate the optimal concentrations of dietary protein and lipid for cobia , a pelagic fish showing great potential for offshore cage culture in tropical and subtropical waters. In the first trial, casein was added to a fish meal-based basal diet to replace starch to render protein concentration gradation ranging between 36% to 60%. All seven diets were estimated to be isoenergetic. After an 8-week growth trial, juvenile cobia (initial weight 33 g) fed the diets containing protein concentrations of 44%, 48% and 52% generally attained higher weight gain and feed conversion than the other groups. Polynomial regression analysis revealed a weight gain peak at a dietary protein concentration of 44.5%, which is regarded as the most suitable level for maximum fish growth. In the second trial, the cobia were fed seven isonitrogenous and isoenergetic test diets containing lipid concentrations ranging from% 3 to 18%. Growth of the fish (initial weight 41 g) was lowest when the dietary lipid concentration was 3%. Weigh gain increased with increasing lipid inclusion and then leveled off. The broken-line analysis that best expressed the response pattern shows a breakpoint when dietary lipid concentration was 5.76%. No significant growth enhancement was observed when the lipid levels were increased beyond the breakpoint to the highest lipid concentration tested (18%).