نشریه توسعه آبزی پروری
سال هجدهم شماره 2 (تابستان 1403)

In this study, the sperm quality indicators of rainbow trout breeders in selected Specific Pathogen Free (SPF) farms of the country were investigated in order to plan the long-term preservation of rainbow trout sperm through cryopreservation and creating a sperm bank in the next phase. Sperm samples from 24 breeders from six selected SPF farms from West-Azerbaijan and Mazandaran provinces were collected and evaluated. The average density of sperm is 7.83 ± 4 billion per milliliter, the average volume of extracted sperm is 9.2 ± 1.6 ml, the average percentage of motility and its duration were 78.7 ± 10.3% and 26.6 ± 4.4 seconds, the average pH was 7.74 ± 0.23 and the fertilization percentage of the samples was as 92.8 ± 1.2%. The results showed that the pH 7.7-7.8 is the most appropriate value for inducing motility and its increasing or decreasing relative to this value causes a decrease in fertilization efficiency. Also, a positive correlation between pH and sperm motility (r = 0.533) and fertility (r = 0.67) was determined. According to the obtained information, the characteristics of the best sperm sample is selected for long-term storage and the creation of a genetically diverse sperm bank and targeted management of rainbow trout reproduction.

Breeding and production of fish in sea cages is one of the most common methods of commercial production of aquatic animals in the world. It is possible to develop aquaculture in the Caspian Sea by fully respecting the biotic, abiotic, social, and economic conditions, as well as the environment, with regard to sustainable development. Breeding fish in cages is very important from an economic point of view, and determining the challenges and obstacles before investment in order to reduce the investment risk plays a fundamental role in it. The purpose of this article is to investigate the economic challenges of cage culture development on the southern shores of the Caspian Sea using a combination of SWOT and FAHP analysis and then determine strategic priorities based on the Quantitative Strategy Planning Matrix (QSPM). In order to meet the challenges and also formulate strategies, the SWOT analytical model was used, and the opinions of 30 fisheries experts were obtained through face-to-face interviews and completing questionnaires in 2020-2021. According to the final score obtained, opportunity factors got 2.89 points, and threat factors got 3.54 points. As a result, the threat points prevail over the opportunities, and it shows that the current situation of this activity requires strategies in the field of adopting solutions to reduce threats. According to the total scores of the obtained matrix, the score of external factors indicates the need to formulate a defensive strategy in order to reduce the minimum risk of investment. According to the SWOT analysis, the strategies with the highest score are "development of standards and criteria and locating suitable areas for cage fish breeding sites," "allocating low interest loans and encouraging investors in order to facilitate investment," and "sustainable development in order to prevent Changing the use of valuable agricultural land" and "attention to export, introduction, and cultivation of species with global marketability" were presented in order to solve the existing challenges and suggestions to make the fish farming industry in the Iranian regions of the Caspian Sea.

The application of probiotics in aquaculture has been increased in recent years due to the many benefits for fish health. The most important factors in reducing the viability of probiotics during passing through the digestive system are low pH in stomach and proteases and bile salts. Encapsulating of probiotics within biodegradable nanoparticles has been found to increase their viability and efficiency in fish gut. In the current study, the effects of microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss) were evaluated. An experiment was designed with four treatments each with three replicates. 480 juvenile rainbow trout average (±SD) initial weight of 25.53±.82 g was assigned to fifteen experimental tanks. Fish in T1 received Lactobacillus rhamnosus encapsulated by internal emulsification with alginate / chitosan, T2 were fed with alginate/chitosan enriched free probiotic diet, T3 received bacteria without any encapsulation and T4 received basic diet as a control group. All treatments were fed with experimental diets for 60 days. Fish were sampled on days 30 and 60 and some of the immunological parameters consist of Lysozime, Complement, Total protein, Albumin, Globulin and NBT were measured. Results showed that lysozyme in treatment of encapsulated by internal emulsification significantly was higher than other groups at day 30 and 60 of experiment (p<0.05). Also, a significant increase was served in the total protein and globulin in T1 and T2 at day 30 compared to the other groups and at day 60 compared to the control group (p<0.05). Generally, it can be concluded that the microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan has significant effects on some of the immunological parameters in rainbow trout and improved the immune responses in this fish. Results showed that lysozyme in treatment of encapsulated by internal emulsification significantly was higher than other groups at day 30 and 60 of experiment (p<0.05). Also a significant increase was bserved in the total protein and globulin in T1 and T2 at day 30 compared to the other groups and at day 60 compared to the control group (p<0.05).
Generally, it can be concluded that the microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan has significant effects on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss) and improved the immune responses in this fish.

The nutritional value and special properties of Artemia have led to its use as a food and biological model in aquaculture. L-Carnitine supplementation stimulates the oxidation of fatty acids, increases nitrogen retention and resistance to environmental stress, and L-Arginine nutritional supplementation is effective in protein synthesis, nitric acid and growth hormone growth and survival. In this study, the effect of Nanochloropsis oculata micro algae enriched with L-carnitine and L-arginine supplements on growth, environmental stress, absolute fecundity and saturated fatty acid profile in Artemia feransiscana was investigated. L-carnitine and L-arginine were applied separately at concentrations of 0, 1, 10, 100 and 1000 mg/l. Artemia cysts under special hatching conditions and Napolius were fed with N. oculata microalgae with two states, enriched conditions and without enrichment (control treatment) separately in 30 days. The results were compared and it was shown that the highest saturated fatty acid (SFA) with nutritional treatment L-carnitine 10 mg/l and the lowest was in the control treatment. The highest mortality percentage of ammonia shock was related to rich treatment with 1 and 100 mg/l L-carnitine which showed a significant difference with the control treatment (p<0.05) and the lowest was related to 1 mg/l L-arginine treatment and control treatment. In hypoxia shock, the highest mortality percentage was observed in the diet with L-carnitine 1 and L-arginine 1 and 100 mg/l and the lowest in the diet with L-carnitine 10 mg/l, all of which showed a significant difference with the control treatment (p<0.05). In  adult Artemia breeders,  the lowest quality indicators  were related to L-carnitine treatment at all doses except 1000 mg/l and the highest were related to L-arginine treatment except 100 mg/l plus 1000 mg/l. L- carnitine that showed a significant difference with the control treatment (p<0.05) .The highest amount of absolute fecundity is related to the nutritional treatment rich in L-arginine 1000 mg/l and the lowest is the control treatment, which shows the positive effect of both supplements on increasing the absolute fecundity. Overall, the results showed that the use of the mentioned nutritional supplements with N. oculata microalgae in A. franciscana nutrition in specific doses can be effective in increasing production and quality in the aquaculture industry. Therefore, according to the environmental stress conditions, improving the fecundity performance and achieving a higher quality index, the optimal doses of each supplement can be used.

The purpose of this study was to determine the frequency of Vibrio parahaemolyticus and to identify pathogenic and non-pathogenic strains of this bacterium using a series of biochemical tests and polymerase chain reactions from the shores of the Caspian Sea (Gilan Province). The water and sediment samples of the Caspian Sea were collected from the depth of 30-50 and 10-20 cm respectively by aseptic method. Sampling date, sampling location, temperature, pH and salinity were measured. Isolation and identification of environmental isolates was done using standard methods in order to determine the genus and species using specific media such as thiosulfate citrate bile sucrose and Vibrio chrome agar. A total of 55 isolates were identified by biochemical, phenotypic and polymerase chain reaction tests. From the total of 55 cases of Vibrio parahemolyticus isolated, the frequency of tdh and trh genes was 1 case (1.8%) and 3 cases (5.4%) respectively. This study showed that Vibrio parahaemolyticus, which have pathogenic potential, should be continuously monitored as agents of contamination of coastal waters. The isolation of these species indicates a health warning for people who use raw seafood or are in direct contact with the waters of the Caspian Sea are in this area.

The aim of this study was to investigate the effect of using basalt in reducing the nitrogen content of water and the growth performance of goldfish (Carassius auratus) for 60 days.

For this purpose, 245 pieces of goldfish with a mean weight of 9.42 ± 0.15 g and a longitudinal mean of 3 ±0.02 cm were purchased and after adaptation for one week in distribution experimental treatments. Were. Experimental treatments included control treatment (without filter), zeolite with 10 g/l, basalt with different amounts of 10, 20 and 30 g/l and for each level of filter, fish density during the experiment, two densities of 1.5 And 3 cm per liter were considered, which were randomly distributed to 25 pieces of fish for a density of 1.5 and 50 pieces for a density of 3 in 50 liter aquariums.

The results of this study showed that the presence of filtration had a positive effect on fish growth rate and fish had better growth factors in treatments of both densities that had filters compared to the control group (p<0.05). Ammonia, nitrite and nitrate levels in the eighth week of the study in treatments containing filters of both densities were significantly lower than the control treatment and did not exceed the toxic range (p<0.05).

According to the studies, it was found that basalt volcanic rock has a very high ability to absorb nitrogen compounds in water and 10 g/l basalt can be treated as a substitute for 10 g/l zeolite with a long reduction time more suggested.

In this study, the effect of different levels of Fish Phos soluble mineral supplement (0, 2, 4 and 8 ml/kg diet) on the growth and nutritional performance of juvenile Sterlet sturgeon (Acipenser ruthenus) was investigated. For this purpose, a total number of 360 fish with 17.1 ± 0.2 g initial weight (mean ± SD) and 17.3 ± 0.1 cm total length were randomly assigned to 12 circular concrete tanks (1.85 m diameter and 0.25 m depth). The fish distributed in 4 treatments with 3 replicates (30 fish per tank) and fed for 8 weeks. The results of growth and nutritional indices showed that the highest amount of feed conversion ratio and voluntary feed intake was observed in the fish fed with 8 ml/kg mineral supplement, which had a significant difference with the control and other treatments (p<0.05). The highest survival rate was observed in the control treatment and 2 ml/kg diet, and with an increase in the dose of the supplement, the survival rate decreased (p<0.05). In other parameters including final weight, weight gain, body weight increase, specific growth rate, average daily growth, condition factor and feed intake no differences were observed (p>0.05). The present study showed that this mineral mixture could not have a positive effect on the growth and nutritional indices of juvenile Sterlet sturgeon in the studied weight range, and with increasing dosage, the survival rate was also decreased. Therefore, using this supplement in lower doses and for a longer period with a more complete combination of other elements can be recommended.

In this research, population characteristics and length-based spawning potential ratio (LBSPR) of skipjack tuna (Katsuwonus pelamis) were investigated. For this purpose, information was collected from 4 fishing areas on the coasts of Sistan and Baluchistan province, including Bris, Pasabandar, Pozam and Kanarak. In total, more than three thousand fish were bio-measured in the research stations, and the growth indices were infinite length L∞ = 92(cm), annual growth coefficient K = 0.68, annual natural mortality 0.7 = M, the annual fishing mortality F=0.37, the total annual mortality Z=1.07 and the annual exploitation coefficient E=0.35 and the time of zero length to=-0.17 and the amount of growth performance index Φ'=3.76. The ratio of length-based spawning potential ratio (LBSPR) in 2022 for this species was LBSPR=0.42 (0.38-0.45). This research showed that this species has medium vulnerability and medium stock status, and also the annual harvesting rate of this species is lower than overfishing.