Fang Qiao, Samwel Mchele Limbu, Juncheng Yuan
et al.
High-fat diet (HFD) affects flesh quality in fish, but the dynamic changes in flesh nutritional composition and texture parameters have not been comprehensively studied. In this study, six replicates of thirty Nile tilapia (Oreochromis niloticus) weighing 5.5 ± 0.3 g were fed a medium-fat diet (MFD, 6 % fat) or a HFD (12 % fat) for eight weeks. The results showed that feeding the fish on HFD increased body weight and lowered feed intake than those fed on MFD. However, the fish fed on MFD had significantly higher phospholipids (PL), phosphatidyl choline (PC) and phosphatidylethanolamine (PE) contents in muscle than those fed on HFD, primarily during sixth and eighth weeks. The fish fed on HFD accumulated more n-6 polyunsaturated fatty acids (PUFAs) in muscle, meanwhile fewer n-3 PUFAs as feeding continued. The amino acids changed mainly from the sixth week, when HFD feeding generally reduced essential amino acids (EAA) and half essential amino acids (HEAA) contents in muscle. The fish fed on HFD up-regulated the genes related to enhanced fiber hypertrophy such as myogenin (MyoG) and myogenic factor 6 (myf6) than those fed on MFD during the second and fourth weeks. Consequently, this led to reduced muscle fiber density and flesh hardness in fish fed on HFD from the sixth to eight weeks. Altogether, our study indicates that the nutritional composition and flesh texture parameters are modified during HFD feeding in Nile tilapia at different time points such that the regulation of each parameter has a distinct “time window”.
Md. Rabiul Awal, Md. Ashikur Rahman, Rubaiya Pervin
et al.
ABSTRACT This study focuses on inducing spawning in the vulnerable fish species Esomus danricus using pituitary gland (PG) extract. Both male and female fish received intramuscular pituitary gland injections in a 1:1 ratio. Female fish were administered doses of 4 (T 1 ), 6 (T 2 ), and 8 mg kg −1 (T 3 ), while male fish received a consistent dose of 2 mg kg −1 across all treatments. Within 3–4 h of injection, the fish exhibited courtship behaviour. The average spawning rates, expressed as mean ± standard deviation, were 27.33% ± 1.77%, 49.43% ± 2.31%, and 77.67% ± 4.87% in April; 35.63% ± 2.85%, 60.67% ± 4.11%, and 87.33% ± 5.87% in May; and 37.69% ± 3.40%, 65.52% ± 4.55%, and 95.67% ± 6.09% in June for T 1 , T 2 , and T 3 , respectively. The latency period for spawning was observed to be 6–9 h across all treatments. The highest fertilisation rate was recorded in June at 93.53% ± 6.12% for T 3 , while the lowest was in April at 53.67% ± 4.60% for T 1 . Similarly, the highest hatching rate was detected in June at 91.27% ± 5.78% for T 3 , and the lowest in April at 30.33% ± 3.91% for T 1 . Hatching occurred within 20–24 h for all treatments, and post‐yolk sac absorption was noted within 60–72 h. This study successfully standardised breeding doses, offering promising prospects for the conservation and propagation of the native small fish species, Esomus danricus .
Erna S. Macusi, Ivy M. Nallos, Charlen Mae G. Canales
et al.
Women fish vendors actively participate in the fishery sector but they face various challenges regarding their financial capital and opportunities. There is a power imbalance within the market as men seem to dominate and women hold no power or voice to protect their rights. This study provides valuable insights regarding the perceptions and experiences of these women in the Davao region, by not only focusing on the role of women in fisheries and major fish markets in Mindanao, Philippines, but also on their contribution and the challenges they meet. We have conducted semi-structured field interviews with women fish vendors (n = 99) and in-depth follow-up interviews to validate the results (n = 80). Among respondents, 90% in Tagum, 80% in Panabo, and 75% in Davao City were vendors who did not own their stalls. Despite women’s active involvement in fish trading activities such as fish vending, fish brokering, and financing in the market, many of them do not have stalls on their own. It was found that women participate in the fish marketing sector because they received previous training from family members involved in the business (29%), or they wanted a well-paying job (19%), or it was their only economic opportunity (14%). Another reason was profitability (9%) to support their families (9%) and children (8%). Common problems encountered by women in the fish market included a decline in customers (40%), work exhaustion due to the combination of their market and domestic duties (14%), and rude customers and employers (10%). In addition, women also reported challenges regarding mobile vendors (9%), low fish prices (8%), and not having access to financial credit (8%). Many of the women support their husbands by providing additional income for their families. Overall, women fish vendors play a critical role in the local economy of their villages and families. This implies that greater support is needed for women to have financial access to fishing businesses and become beneficiaries of training and livelihood development programs while helping their families overcome food insecurity and poverty.
The Yellow River estuary is one of the three largest estuaries along the coastal waters of China, along with the Yangtze and Pearl River estuaries. Its adjacent seawaters are rich in biological resources, with abundant fish habitat, spawning grounds, and migration channels in the Bohai Sea and the Yellow Sea. However, as the waters are too shallow for a survey ship, data was insufficient for research in the intertidal zone of the salt and freshwater interchange. Instead, by interviewing and analyzing the daily catches by the set net of the local fishermen, this study explored the fishery biodiversity in the intertidal zone of the Yellow River estuary from April to November 2020. Yellow River estuary is rich in fishery resources, especially small fishery organisms and fish recruitment stocks. There were monthly variations in the dominant species composition and biodiversity index. A total of 61 species were recorded, most of which were fish and crustaceans. The diversity, evenness, and species richness index increased in summer (July and August) and decreased in autumn (October and November). By cluster analysis of the species compositions, the surveyed months can be divided into two groups: May to September, and October to November. Lateolabrax maculatus and Liza haematocheila were the most common and dominant species in all surveyed months. The main contributors to the catch of each month were: snails from April to July, snails and fish in August, fish in September, and crabs from October to November. Catches by the set net were mainly composed of individuals with body mass < 2 g from April to September. From body mass-frequency distributions, fish with body mass < 10 g were the main contributors to total catches from April to September. The mean body mass of fish in all surveyed months was 13 g/ind.. The dominant fish species with body mass with < 20 g were: Gobioidei in April; L. maculatus in May; Konosirus punctatus in June; Pennahia argentata, Gobioidei, and L. haematocheila in June to August; and Sardinella zunasi, Thrissa kammalensis, T. mystax, Sillago sihama, Tylosurus melanotus, Gobioidei, and L. haematocheila in September. From the above results, the local set net fishery survey proved to be an effective method of collecting fishery data in the intertidal zone and can be incorporated in studies considering the distribution of fishery resources and breeding grounds in the seawaters adjacent to estuaries. In addition, this study provided clear evidence that set net fishing practices could severely impact the natural recruitment and stock enhancement of fish resources due to the low selectivity of nets and the overlap with larval fish migration channels. The number of larval fish captured by the set net fishery was, roughly estimated, several times higher than the local enhancement released. To minimize the effects of net mesh size, considering the spatial-temporal distributions of fish larvae, set net fishing practices should be concentrated to summer and early autumn, though further research is required to comprehensively account for both the protection of fishery resources and livelihoods.
Odang Carman, Andri Iskandar, Ching-Fong Chang
et al.
Highlight Research
• Sex reversal for orange-spotted grouper Epinephelus coioides
• The application of 17α-methyltestosterone induce sex change
• The stability of sex change need more investigation
Abstract
The occurance of hermaphrodites in grouper fish causes a scarcity of male parents, so an alternative is needed to accelerate sexchange to male at a young age. The present study was expected to scrutinize the mechanisms of sex-change in fish in the early change process, and whether the testis converted from immature ovary using 17α-methyltestosterone (MT) would recover after the termination of MT treatment. MT-induced sex-change and 5-aza-2'-deoxycytidine (5-Aza) were connected as DNA methylation inhibitors to comprehend the alternation of gonadal soma cells. The orange-spotted groupers were used at the developmental ages and fed a diet containing MT at 50 mg/kg for three months and then a normal diet for a month. In the first week and second week fish injected with 5-Aza intraperitoneally during the MT-oral administration. Most of the fishes in the control group had immature ovaries, but all the females fed with MT, had immature spermatogenesis. However, one month after the withdrawal of MT treatment, the sex of the fish returned to female-like even though the fish have undergone MT-induced masculinization. This outcome demonstrates precocious sex-change from under yearling, orange-spotted grouper utilizing oral MT treatment is impermanent. All the females of 5-aza treatments showed no spermatogenic cells. In this study, lower growth rates were demonstrated by the MT-treated groups. The impact of this metabolic change was clear after the end of the hormone oral administration since the decreased growth of the groups treated for three months.
Gopika Radhakrishnan, Gopika Radhakrishnan, Nina S. Liland
et al.
Atlantic salmon (Salmo salar) were fed diets containing black soldier fly larvae (BSFL) meal at two inclusion levels for 13 months in open sea-cages. BSFL meal replaced plant-based ingredients and dietary insect meal inclusion levels were at 5% and 10%. A commercial salmon diet was fed as a control diet. Fish were reared from ~173 g to ~ 4 kg and were randomly distributed into nine open sea-cages with ~6000 salmon/cage (12×12 m2; 1900 m3). Fish from the sea-cages were sampled at two time points (mid and final samplings) to study the dietary effects of BSFL meal on the general health and welfare. Monthly assessments of sea-lice and gill score were conducted to evaluate the overall well-being of the salmon. The findings from the current study revealed that dietary inclusion of BSFL meal up to 10% did not have any significant effects in general growth, welfare or survival. However, significant positive response was observed in the general skin mucosal, hematological, and gene expression profiles of salmon. Notably, the group of salmon fed with 5% BSFL meal showed a significant decrease in plasma aspartate transaminase and alanine transaminase. Also, a significantly higher expression of interleukin1β in both skin and gill along with upregulation of matrix metallopeptidase9 and mucin18 in gill were observed in salmon fed BSFL at 5%, which aided in increased immune responses. Apart from that, this group had significantly higher mucus secretions, decreased cortisol response and increased number of erythrocytes. Furthermore, the delousing stress had a significant effect on the plasma cortisol, and these responses were independent of the dietary effect. Moreover, these immune responses behaved differently at different fish size and time points, acknowledging the influence of various factors in immune modulation. Overall, the findings from this study showed the effects of dietary BSFL meal to modulate the immune status of salmon. This study aims to fill the existing knowledge gaps regarding the impact of incorporating BSFL meal as a functional feed ingredient into the salmon diet on health and immune status replicating real farm conditions.
The wild eel fishery and eel farming are playing an increasingly important role in aquaculture. Most of the Anguillid eel fries at their glass eel stage are caught in the two provinces of Vietnam, viz., Phu Yen and Binh Dinh, which accounts for over 80% and 10-15%, respectively. The stages of raising eels in Vietnam are very diverse with the survival rate of Anguilla Marmorata is approx. 60% through glass eel and elver stages. The major eel grow-out area of Vietnam is in Mekong delta. Ca Mau province is the highest in eel farming among the 14 provinces in the country. There are over 1,000 eel farms produced about 2,000–5,000 tons of eel in Vietnam at this moment. Around 95% of the total number of farms produced giant mottled eel (A. marmorata), and most of the production (70%) was used for domestic consumption, while30% was exported to the adjacent countries.
Increasing evidences have showed that a tight link among pathogen infection, physiological indicators and intestinal microbiota. To investigate effects of Enterocytozoon hepatopenaei (EHP) infection to growth retardation and intestinal microbiota, different sized Pacific white shrimp (Penaeus vannamei) infecting with EHP were studied. The shrimp with big, medium and small sized groups were from same batch of postlarvae and reared in one pond under the same diet and environmental conditions. Number of EHP copies revealed that the more EHP copies the smaller size of shrimp individuals. Denaturing gradient gel electrophoresis (DGGE) profiles showed intestinal bacterial patterns of small sized shrimp were similar to the middle sized shrimp, rather than the big sized shrimp. It implied that intestinal microbiota were influenced by severity of EHP infection and suggested the different sizes of shrimp were due to the successive infection period of EHP. Among the different sized groups, the relative abundance of Vibrio of small group was the highest, suggesting EHP infection could result in higher susceptibility to pathogen invasion. Our findings provided the evidence intestinal bacterial patterns altered by infection of EHP, the more EHP copies the smaller size of shrimp, and different sized individuals due to successive infection period of EHP.
Abstract Life history strategies are based on the characteristics of organisms that affect their fitness. Two environmental factors important in determining the life history strategy of organisms, including sea urchins, are stress, conditions that reduce production and disturbance, partial or total destruction of biomass. Disturbance includes predation. Different characteristics of different life history strategies are associated with different combinations of levels of stress and disturbance. The hypothesis that these characteristics are associated with particular habitats was tested by predicting where sea urchins with particular life history characteristics would occur. The habitats considered (the deep sea, Antarctic waters, tropical reef flats, kelp forests and tropical seagrass beds) differ in the levels of stress and disturbance. Species with different life history characteristics were found in the predicted habitats. Recognition of the life history strategies of sea urchins species is basic to understanding their biology and ecology. Knowledge of the strategies of extant sea urchins is useful for paleobiological and paleoecological studies. Strategies have important implications for fisheries management, conservation and evaluation of species for aquaculture. Habitats may be expected to change with ocean warming and acidification. The response of sea urchin species to the predicted changes may vary with life history strategy.
Abstract The high nutritional quality of common sole Solea solea increases its value for the fishery industry and for the aquaculture sector. To ensure the expansion of its production, it is necessary to implement farming and broodstock management technique to produce high quality eggs and larvae. This work summarizes eight years of study on reproductive performances, growth and parental contribution of a common sole broodstock from the Mediterranean-North Adriatic Sea. The broodstock (11 females and 13 males) reached the peak of fecundity after 5/6 years of captivity, with a production of 296,476 and 376,541 × 103 of total eggs kg−1 female with a fertilization rate of 31.6 ± 18.3 and 41.9 ± 23.8 %, respectively. Results shows that variations in temperature cycles are pivotal for a successful breeding season, and body condition during the first 3 years of captivity was the most important parameter positively correlated to parental contribution for both males and females. Parental contribution was assessed by eight species-specific microsatellite loci during the first 3 years of reproduction. Although the two sexes displayed different temporal trends, parentage assessment demonstrated an overall increase in the number of active breeders. However, only 13 couples out of 50 produced the 70.4 % of the larvae in year 5, confirming the same reproduction behavioural pattern in Mediterranean common sole than that observed both in Senegalese sole and in common sole of Atlantic origin. This work provides valuable data needed to understand the mechanisms behind the maturation characteristics of this species and support future strategy for the establishment and management of Mediterranean common sole aquaculture.
Although sea cucumber Holothuria scabra has always been part of the traditional exploitation of the benthos in Mahout Bay of Arabian Sea, the foreign demand for the product and its high price have put increased pressure on the resource leading rapidly to overfishing. Aquaculture of this species has developed as a response to the overfishing problem but has not been yet studied in Oman. As a first step to evaluate its potential for aquaculture in Oman it was thus necessary to conduct hatchery trials. Four hatchery runs were conducted to evaluate the quality of the local broodstock, the response and efficiency of in vitro maturation and fertilization and the success of larval development and rearing. Collected animals of 200-600g were transported by road for 5 hours with zero evisceration to the Hatchery station. In vitro maturation and fertilization success of more than 90% were achieved using maturation inducing fractions method leading to the development of mature eggs and normal embryos larvae. Auricularia larval stages were completed within 15 days and fed normally on microalgae Phaeodactylum tricornutum, Chaetoceros sp. and Nanochloropsis sp. Settlement rate was reached 9% for pentactula larvae. However, a high mortality of 70% was observed during early larval development caused by ciliated protozoans and copepods attack. The culture of Holothuria scabra population in Oman is thus promising but further research is needed to ensure higher survival rates, particularly in the early larval stages where adequate water filtration and sterilization is essential.
In general, land use in Pasangkayu Regency is dominated by forests, both protected forestsand production forests, plantations especially oil palm plantations, mixed gardens, rice fields bothirrigated rice fields and rainfed rice fields, as well as shrubs, weeds, mangrove forests andwetlands, beaches, settlements, government buildings and other infrastructure facilities. This studyaims to (1) Know the biophysical and chemical aspects of the waters, (2) Analyze the suitability ofaquaculture land in supporting the development of aquaculture, and (3) Assess strategies fordeveloping aquaculture ponds. The results showed that (1) the biophysical and chemical aspectsof waters in coastal and marine areas, where coastal ecosystems, physical and chemical aspects ofthe waters strongly supported aquaculture activities, (2) the results of suitability of aquacultureland in the development of pond culture in Batu Oge Village Very suitable land with a land area of1,72 Ha, Adequate According to 61,07 Ha, and Appropriate 122,34 Ha. Malei village landsuitability is quite suitable 16,47 ha, and according to 334,18 ha. Mertasari Village landsuitability In accordance with the land area of 26,19 ha, and Village of land suitability inaccordance with 2,27 ha of land area, and (3) Strategy for the development of pond culture inPedongga District, Pasangkayu Regency, includes 3 strategies: technical meeting meetingbetween the local Fisheries Service with pond farmers to teach CBUB and CBIB, optimize the useof farm land, and determine the boundaries of the area for the development of ponds and oil palm.
George Tserpes, Enric Massutí, Fabio Fiorentino
et al.
The present work examines the spatio-temporal biomass trends of Mullus barbatus and Mullus surmuletus in the Mediterranean Sea through the analysis of a time series of data coming from the Mediterranean International Trawl Surveys (MEDITS), accomplished annually from 1994 to 2015. The biomass of both species showed clear declining trends below 150 to 200 m depth, which were steeper in the case of M. barbatus. Increases in temporal biomass trends were observed for M. barbatus from 2008 onward in most geographic sub-areas (GSAs), while stability was mostly observed for M. surmuletus. For both species, dynamic factor analysis revealed similarities among neighbouring GSAs and the subsequent cluster analysis identified two major GSA groups corresponding to the eastern and western basins of the Mediterranean. Overall, the results suggested that the combined effects of fishing and environmental conditions determine species abundance variations, but the relative importance of each component may vary among areas.