JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2024 | Volume:13 | Issue:3|Papers Count:7

Evaluation of the antimicrobial activity of bacteria in the aquaculture ecosystem is the first stage of probiotic bacteria screening studies. The aim of the present study was to isolate the intestinal bacteria of cultivated Vanammei shrimp with antimicrobial activity against pathogenic bacteria in vitro and in vivo. For this purpose, sampling of shrimp culture sites in South Tiab and North Tiab was done in 3 stages. The results of counting culturable bacteria using Zobell agar culture medium showed that in South Tiab site, the average number of bacteria in shrimp intestine samples was from 3.66 × 106 CFU/gr in the first stage of sampling to 4.63 ×106 CFU/gr in the third stage. With a similar trend, the changes of this amount in the North Tiab site fluctuated from 16.4 ×106 CFU/gr to 16.16 ×106 CFU/gr. Evaluation of the antimicrobial activity of the isolates using the agar diffusion method showed that 9, 6, 4 and 3 isolates respectively compared to V. alginolyticus, V. harveyi, V. parahaemolyticus and P. aeroginosa showed antimicrobial activity.

The aim of this research was to produce low-fat and functional fish nuggets using the inulin prebiotic. In this study, inulin was used at concentrations of 0%, 1.5%, 3%, and 4.5% to enrich the fish nuggets. The results showed that increasing the concentration of inulin led to a reduction in fat content in the fish nuggets, with the greatest reduction observed in the treatment containing 4.5% inulin (T3). Additionally, the quality attributes of the fish nuggets, including moisture content, cooking loss, and shrinkage, were improved with the use of inulin. Higher concentrations of inulin resulted in a decrease in lightness (L*) and yellowness (b*) and an increase in redness (a*) during both pre-frying and final frying step. Inulin also improved the textural properties of the nuggets, such that with increasing inulin concentration, hardness, cohesiveness, chewiness, and gumminess decreased, while springiness and resilience increased. This study demonstrated that enriching fish nuggets with 4.5% inulin can effectively reduce fat content and enhance the quality of fried fish nuggets.

To study the effect of baits type and three lights, green, blue, and white, on the fishing efficiency of Largehead hairtail (Trichiurus lepturus) handline fishing 11,951 samples were done from February to May 2022 in the northern coast of the Oman Sea, Remin Fishing Port. The results showed that only the season and bait had a significant effect on the weight and number of caught T. lepturus caught (P<0.05), while the type of lamp and its interactions did not have a significant effect (P>0.05). The highest CPUE was observed in the months of February and March, using Rastrelliger kanagurta as bait, green LED lamp, at a water depth of 60-110 meters, and a hook depth of 20-30 meters. The use of R.kanagurta bait compared to Sardinella gibbosa has led to a significant increase in the catch of T. lepturus (both in terms of relative frequency and weight), which is recommended to improve the efficiency of hook fishing for fishermen. Due to catch per unite effort and for efficiency of catch rate of T. lepturus in the area, it seems suitable bait, green light and suitable depth of the hook must be used.

The survey of the fish assemblage in the planned place to establish artificial reefs in the western and eastern bays of Jask was carried out in the winter and spring of 2024. Sampling was done by Gillnet and Trap methods in 4 stations located in the western bay and eastern bay of Jask at a depth of 10 to 30 meters. 68 aquatic species (60 fishes, 5 crabs, 2 oysters, and 1 shrimp) were sampled and recorded. Of these, Nemipterus japonicus (32.6 %) was the most abundant, Saurida tumbil (12.6 %), Anodontostoma chacunda (12.5 %), Ilisha megaloptera (9.8 %), Scomberoides tol (6.4 %), Sphyraena putnamae (4.1 %), Lactarius lactarius (2.6 %), Muraenesox bagio (2 %), Pomadasys kaakan (1.9 %), Otolithes ruber (1.6 %) located in the next rank. The average catch per unit of effort of gillnet was 45±10.2 kg/piece×hour and for Trap 7.3±4.2 kg/trap×day. In this research, it was found that the population of species related to artificial reefs, such as Epinephelus coioides , Lutjanus johnii , and Lethrinus nebulosus were relatively low, and mainly below the maturity size, it seems that the stocks of this group of fish need to be enhanced. Therefore, it is recommended to consider the target species in the design of the structure and arrangement of the artificial reefs, on the other hand, the shelter and protective aspects of the artificial reefs for the reef-dependent juvenile also be considered.

In the present study, the fish protein isolate (FPI) of wastes of Siberian sturgeon (Acipenser baerii) has been substituted with fish minced (10, 20, 30, and 40%) in preparing fish nuggets. After preparing fish nuggets (88% Silver carp fillet) and initial cooking, the parameters such as approximate analysis, product yield, weight loss, pick-up, microbial growth, and sensory evaluation were investigated. The results showed that the lowest amount of moisture is related to the IP40 Group and no significant difference exists between other treatments. In comparison, the amount of protein in the control sample was the highest (18.00 ± 0.04) and it was decreased with the increase of FPI substitution (P<0.05). The highest amount of weight loss during final cooking was related to the control and IP10 treatments, and the highest product yield was associated with IP20, IP30, and IP40 treatments (P<0.05). The microbial growth results did not show any significant difference among the treatments (P>0.05). Moreover, the sensory evaluation showed the control group, which was only with fish minced, had better taste, smell, texture, etc. than the treatments containing isolated protein. The results of this research showed that the minced fish of silver carp and the FPI by-product can be used to produce fish nuggets, and although in some physical properties, the nuggets containing higher amounts of isolated protein have shown better results, according to the amount of protein and sensory evaluation, the control and the sample containing %10 FPI had better results.

The morphometric and meristic traits of the dominant demersal flathead fish P.indicus, G.suppositus, and G.scaber which were caught as by-catch of shrimp (bottom trawl) and also in coastal stake net (moshta), During the period from April 2022 to October 2023, it was evaluated comparative in different age groups. A total 19 morphometric and six meristic characteristics were recorded. The average total length and weight of the fish in P.indicus (23.2 ± 6.9) cm, (99.9 ± 78.4) gr and in G.suppositus species (20.6 ± 4.7) cm, (67.4±33.7) gr and also in G.scaber (18.5±2.9) cm, (31.0±17.2) gr. In the studied species, among all the measured morphometric traits (except head hight, body hight and Eye part head higth), the rest of the traits in P.indicus species have the highest and lowest (except head length and Anal fin hight ) has been observed in G.scaber. In the investigation of meristic traits, the highest and lowest number of gill rakers in G.suppositus and G.scaber, respectively. The number of rays Pectoral fin was the highest in G.suppositus and the lowest in P.indicus.  species.the three studied species in different age groups, showed significant differences in various morphometric and meristic parameters (except for the number of rays of the first dorsal fin) (P<0.05). The three studied species clearly distinguished themselves in the present research. The results of this research showed that the analysis of morphometric and meristic traits is a useful tool for the separation of flatheads species studied in this research.

Tuna fishes are one of the most important and commericial tuna species in Northern of the Persian Gulf and Oman Sea. The tuna fish stocks Thunnus tonggol was assessed in Hormuzgan coastal waters using software FiSAT . Data were collected minimum 200 fish per month simple randomly from five major traditional fish-landing sites in Hormuzgan Province, from November 2021 to September 2023. The monthly individuals ranging of T. tonggol  from 21 - 108 cm fork length with mean 71.08 ± 1.23 cm.The infinity length and growth parameters (K, L∞) for T. tonggol, were computed 121.17 cm and 0.68 respectively. Growth performance index (Phi Monreo) calculated for T. tonggol , 8.9 which was in agreement with the finding of the other studies in the Indian Ocean. The results showed that this species has a high growth rate in the first 2 years of their life. The (a, b) parameters in power equation length-weight relationship for T. tonggol were (0.00002, 2.94), indicating that T. tonggol has isometric growth. Total mortality, natural mortality, fishing mortality rate and exploitation ratio (Z, M, F, E) were estimated for T. tonggol (2.89, 0.71, 2.18, 0.75). These results indicated that population of T. tonggol  is overexploited and no scope for improving production in Hormuzgan Province. Tuna fish stock are trans boundaries and its fishery management  and long term monitoring programs would be conducted in collaboration countries bordering the Persian Gulf, Oman Sea and Indian Ocean