Search

The current study was conducted to determine the impact of immersion using garlic, sumac, and citric acid on certain qualitative characteristics of Japanese threadfin bream (Nemipterus japonicus) during frozen storage. Fish were immersed with 1% addition of each natural substance and stored at -18 C for 150 days. The results revealed that immersion with garlic, sumac, and citric acid prevented lipid oxidation and reduced the production of free fatty acids (FFA), volatile nitrogen bases (TVN), and thiobarbituric acid (TBA) in the groups treated with natural substances compared to untreated and water-immersed groups. The lowest pH value was 6.11 at day zero for the frozen fish, which increased to 6.98 at the end of storage for the same treatment. The lowest TVN, FFA, and TBA values were observed in the garlic-treated fish at day zero: 4.2mg nitrogen/100g fish, 0.12%, and 0.27mg malondialdehyde/100g fish, respectively. These values increased significantly during the final storage period to 29.4mg nitrogen/100g fish, 0.88%, and 5.41mg malondialdehyde/100g fish for the frozen fish only at 150 days of storage, with significant differences among treatments and storage periods (P<0.05). The lowest percentage of lost fluids was 2.33% for the garlic immersion treatment at day zero, while the highest value was 5.49% for the frozen fish only at 150 days. In conclusion, the study demonstrated the potential use of these substances in immersion as natural antioxidants and inhibitors of enzymatic, microbial, and quality loss. [ABSTRACT FROM AUTHOR]

Surimi industry produces a large quantity of byproducts that are currently being utilized to produce low‐value commodities. This study aims to extract gelatin from pink perch skin and bone obtained from the surimi industry using a green single‐step extraction method. In addition to using a green solvent, that is, acetic acid, the new method combines the multiple steps of pre‐treatment and hydrolysis into one single‐step extraction process. Response surface methodology was used to optimize extraction parameters (pH, temperature, and time) to maximize yield and l‐hydroxyproline (l‐hyp) content. The optimum condition for gelatin extraction was obtained at pH 3, 75°C, and 30 min. At optimum conditions, gelatin yield and l‐hyp content were observed to be 16.07% and 41.26 mg g−1, respectively. The gelatin obtained at optimized condition was further compared with commercial bovine gelatin (BG) in terms of chemical composition and textural, functional, and rheological properties. The results suggested that the optimized pink perch gelatin had higher protein content (92.06%), better gel strength (251.08 g), higher imino acid (18.01%), and improved textural and functional properties than the commercially available BG. The optimized single‐step gelatin extraction method from pink perch skin and bones is a promising, rapid, and efficient method for the production of good‐quality gelatin, which can be further used for the development of high‐value products such as food formulations. Practical Application: Fish gelatin is widely used in food product development. Most of the existing methods of the development of high‐value product such as gelatin, use multi‐step process and harsh mineral acid, therefore, are time‐consuming and harmful to the environment. This study provides a green single‐step gelatin extraction method that provides an efficient, rapid, and convenient method of gelatin extraction and a sustainable solution for fish industry byproduct utilization. The data obtained with this laboratory‐scale study provides a strong basis for scale‐up studies. [ABSTRACT FROM AUTHOR]

A total number of 100 Nemipterus japonicus was collected randomly from the Western Gulf of Suez, Red Sea, Egypt from September to April 2021. After external and internal examinations, two species of parasites were found. The first species was Mothocya melanosticta isopods (both sexes) with a prevalence of 52% and attached externally to the gills and inside the buccal cavity. The second species, Hysterothylacium aduncum nematodes that was found in three types of distributions in 53 fishes. Firstly, adults were found in the gastrointestinal (GI) tract with a high prevalence of about 58%. Secondly, larval stages were found in 52 fishes with a high prevalence of about 57%. Thirdly, adults and larvae were found mixed together in 91 fishes with a high prevalence of 91% inside the GI tract of the same host. There was mixed infestations with M. melanosticta and H. aduncum with a percentage of 51% with several observed signs on the infested fishes. To determine the correct identification of detected parasites, both species were subjected to morphological and electron microscopic examination. Based on the present findings, further studies are recommended on the host-parasites relationship.

The Beibu Gulf is the fourth largest Chinese fishing ground, with rich fishery resources and a significant role in marine fishery production. The feeding ecology of fish is important to explain the structure and function of marine ecosystems. As one of the most important fish species in the Beibu Gulf, Nemipterus japonicus plays an essential role in energy flow and other aspects of the marine ecosystem. Understanding its feeding ecology could provide a basic theoretical basis for the rational utilization and protection of this resource. A total of 248 N. japonicus specimens were collected from Beibu Gulf from January to April and August to December in 2018. The food content composition, feeding intensity, and feeding niche of N. japonicus were analyzed using stomach contents to reflect feeding habits. Combined with carbon and nitrogen stable isotopes, the food source and trophic structure characteristics were analyzed, the trophic level was determined, and the feeding ecology of N. japonicus in the Beibu Gulf was discussed. The stomach content analysis revealed that N. japonicus is a broad-feeding benthic carnivore, which feeds on a large number of species, including eight prey groups, including fish, shrimp, and crab, among which fish and shrimp are the dominant food groups, with a relative importance index of 92.92%. The proportion of food species varied with the season and growth. Fish were an important prey group across all seasons. Moreover, N. japonicus preyed on shrimp in spring, crab in summer, shrimp and polychaetes in autumn, and shrimp and sipunculoidea in winter. With an increase in body length, the feeding habits of N. japonicus gradually change from primarily feeding on shrimp and fish to mainly feeding on fish, and the body length node of feeding transition was approximately 130 mm. There were clear seasonal variations in feeding intensity, with the highest intensity in autumn, followed by that in spring and summer, and the lowest in winter. N. japonicus had a high prey diversity; the Shannon-Wiener diversity index (H') was 1.77, and the Pielou evenness index (J') was 0.64. From spring to winter, the H' and J' values tended to increase and then decrease, and the highest value occurred in autumn, which meant that the feeding niche was the highest in autumn. The number of prey species increased with individual growth, and H' and J' showed an increasing trend with body length. The group with a body length ≥ 160 mm had the largest niche width, which suggested that the food diversity increased with individual growth, and the diet changed to broad-feeding.Based on stable isotope analysis, δ13C was positively correlated with the body length of N. japonicus (P < 0.05), indicating that the trophic source changed with growth. The span of the δ13C (CR) range was 2.86%, indicating extensive basic food sources. The span of the δ15N (NR) range was 4.23%, and the trophic span was more than one trophic level, indicating considerable differences in feeding among individuals. A significant positive correlation was found between body length and δ15N (P < 0.01), which indicated that the trophic level increased with an increasing body length. The trophic level of N. japonicus ranged from 3.21 to 4.46, with an average value of 3.97, indicating that N. japonicus species were middle-high carnivorous animals, and were at a high trophic level in the fish food web of the Beibu Gulf. The trophic level obtained in this study is higher than that obtained in other studies, which may be related to the changes in the composition of the prey, N. japonicus has shifted from feeding mainly on the low trophic level (crustaceans) to the high trophic levels (fish).In terms of trophic structure, the CR value of N. japonicus in the Beibu Gulf in spring and winter was lower than that in summer and autumn, indicating that the basic food source diversity in spring and winter is lower than that in summer and autumn, however, there are fewer prey species in summer, which might be caused by the feeding preference of N. japonicus. Simultaneously, the NR values in spring and summer were greater than those in summer and autumn, indicating that the span of the main trophic sources in the feed was higher than that in summer and autumn, consistent with the seasonal variation of dominant prey. Although the standard ellipse area (SEA) overlaps to different degrees among seasons, the total niche (TA) had clear seasonal differences, signifying that there were certain similarities and specific differences in prey resource utilization, which is beneficial for alleviating the seasonal pressure on the dominant prey. Furthermore, the CR value in different body length groups of N. japonicus showed an overall upward trend with individual growth, indicating that the food source diversity increased with growth. The NR value decreased when body length was greater than 130 mm, which indicates that the average trophic level of the population was concentrated when individuals grew to a certain stage. The SEA overlap rate was higher among length groups, implying that the trophic source components were similar at different growth stages; however, TA tended to increase and then decrease with body length, which may reduce food competition within species by niche differentiation.

A total number of 100 Nemipterus japonicus was collected randomly from the Western Gulf of Suez, Red Sea, Egypt from September to April 2021. After external and internal examinations, two species of parasites were found. The first species was Mothocya melanosticta isopods (both sexes) with a prevalence of 52% and attached externally to the gills and inside the buccal cavity. The second species, Hysterothylacium aduncum nematodes that was found in three types of distributions in 53 fishes. Firstly, adults were found in the gastrointestinal (GI) tract with a high prevalence of about 58%. Secondly, larval stages were found in 52 fishes with a high prevalence of about 57%. Thirdly, adults and larvae were found mixed together in 91 fishes with a high prevalence of 91% inside the GI tract of the same host. There was mixed infestations with M. melanosticta and H. aduncum with a percentage of 51% with several observed signs on the infested fishes. To determine the correct identification of detected parasites, both species were subjected to morphological and electron microscopic examination. Based on the present findings, further studies are recommended on the host-parasites relationship. [ABSTRACT FROM AUTHOR]

Holocolax nemipteri (Pillai, 1973) is redescribed based on specimens of the female recovered from the bucco-branchial cavity of the original host, the Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) in Japan. Copepodid III sex undetermined of the species recovered from the same host is described for the first time in the genus. [ABSTRACT FROM AUTHOR]

The Maximum Entropy Model (MaxEnt) is a high-performance machine learning algorithm that is used to investigate the presence of species and to forecast the possible distribution of a target species according to its maximum entropy under different conditions and to determine the habitat suitability of species. In the present study, habitat suitability modeling for Nemipterus japonicus in the Makoran region (northern shores of the Makran Sea) was performed using the Maximum Entropy Model (MaxEnt). For this purpose, the data obtained from the fishing of Nemipterus japonicus during the period of 2015 to 2019 recorded by the Chabahar Offshore Fisheries Research Center in five areas were used to find points of presence. Based on the results obtained from the model, the variables of sea surface temperature at night and day and chlorophyll a concentration were recognized as the most important parameters in identifying the suitable areas, including the Gowatr bay area. Also, the area under the curve index (AUC) was equal to 0.998, which indicates the high accuracy and efficiency of the model in identifying the most suitable areas of Nemipterus japonicus distribution. The obtained results can be used as an effective tool for effective evaluation of conservation strategies for sustainable yield of Nemipterus japonicus fish stocks. [ABSTRACT FROM AUTHOR]