فصلنامه شیلات
سال هفتاد و ششم شماره 4 (زمستان 1402)

In this study, the effects of different levels of dietary supplementation with probiotic (BioAqua) and soy-bean lecithin on reproductive efficiency (absolute and relative fecundity, number of eggs per gram, egg diameter, percentage of fertilization and percentage of eyed-egg) of female rainbow trout (Oncorhynchus mykiss) were investigated. For this purpose, the broodstock (2.73±0.02 kg) were fed with 5 different experimental diets including control, B2L6 (2 grams/kg of BioAqua probiotics and 6 percent soy lecithin), B2L9, B4L6 and B4L9 with the rate of one percent of their body weight once a day (at 10 A.M) for two months. The highest absolute   relative fecundity, percentage of fertilization, and percentage of eyed-egg were significantly different in B4L9 treatment (7153.01±76.89, 2604.23±23.77, 99±1%, and 97.33±1.15%, respectively) compared to the control treatment (5304.64±143.09, 1950.05±26.46, 93.33±1.15% and 91±1%, respectively; P<0.05). Also, the largest egg diameter was recorded in B2L9 and B4L9 treatments (5.01±0.07 and 5.05±0.04 mm, respectively), which were significantly different from other treatments (P<0.05). Furthermore, the lowest number of eggs per gram was obtained in B4L9 treatment (15±0.3), which had a significant difference with the control treatment (17.2±0.4; P<0.05). The absolute and relative fecundity and number of eggs per gram in B2L6, B4L6 and B2L9 treatments were not significantly different (P>0.05). The result of the current study revealed that simultaneous dietary supplementation of at least two grams per kilogram of BioAqua probiotic along with at least six percent soy-bean lecithin improve the reproductive efficiency in female rainbow trout.

Caucasian scraper (Capoeta capoeta) is one of the native fish of Iran, in the southern basin of the Caspian Sea and Sang Siah Lake of Kurdistan. To study the reproductive cycle of this fish, sampling by gill net was done monthly from June 2018 to May 2019. The biometry of specimen in the Lab was done and sexuality, maturity stages and gonad growth index (GSI) were recorded. The sex ratio of specimen of 1.5 to 1 (female to male), the total length of males 29.3 ± 2.1 cm and the total length of females 32±2.3 cm were recorded. The average weight of males and females were 284.6±50.9 and 378.2±79.3 g, respectively. Also, examining the changes in sexual maturity index (GSI), both sexes had the highest GSI in July. The average relative length of the intestine in this species (6.8±1.29) indicated the herbivorous food regime. The average percentage of empty stomach in the whole period was estimated to be 11.7, which shows that this species is a gluttonous. Also, the highest average amount of gastric index (GI) was estimated in spring. The results of this study showed that July is the peak of sexual maturity and reproduction of this species. Investigation the results of its food habits and preferences in the digestive system showed that this fish prefers algae than other food resources. Due to the high growth and reproduction and also food regime, this fish can be introduced as an economic species to culture and sport fishing in the reservoirs.

When fish is mechanically processed on a commercial scale, usually between 45 and 55% of its weight is discarded as waste. This amount of waste from aquatic processing contains a large number of nutrients, including protein with high nutritional quality, which, despite its need, is not properly used. In order to optimally use this category of materials and also optimally use underutilization fish, several technologies including the pH shift method were taken into consideration. This method, which is based on the dissolution of the raw material in acid and base (alkali), consists of two stages. In the first stage, the pH of the raw material is reduced or increased by using the corresponding acid or base. This causes the muscle proteins to be charged together and then dissolve in the aqueous medium, and the second stage includes the precipitation of the proteins up to their isoelectric point. The protein obtained from this technique has higher nutritional and functional properties than other conventional techniques for producing protein concentrates such as surimi. This article intends to describe the principles of the pH shift process and the recovery of concentrated protein in this way, the advantages and disadvantages of both acid and alkaline methods and its comparison with the conventional (surimi) processing method, which ultimately the nutritional and functional properties of this process. It is discussed in detail.

This study aimed to evaluate the effect of diets containing the white-button mushroom powder (WBMP) on growth performance and some hematological and biochemical indices of juvenile Persian sturgeon (Acipenser persicus). For this purpose, one hundred fifty-three juvenile of Persian sturgeon (47.78 ± 0.39 g) were distributed into nine experimental fish culture tanks with a total volume of 500 liters, filled with 300 liters of water. The fish were fed with diets containing 0.5% white-button mushroom powder (T1), 1% white-button mushroom powder (T2) and 0% white-button mushroom powder (control) as experimental diets for eight weeks. At the end of ‎the experimental period, no significant differences were observed in growth and feed‏ ‏utilization parameters between treatment and compare to the control diet (p>0.05). ‎Hematological parameter such as number of white blood cells was significantly ‎lower in the fish fed with the diet containing 1% WBMP compared to the control diet (p<0.05). The neutrophil percentage was significantly ‎higher in the fish fed with the diet containing 0.5 % WBMP compared to the control diet (p<0.05) as well. MCV, MCH, RBC, Hb, Hct, MCHC, lymphocyte, and monocytes were not different among the treatments (p>0.05). WBMP supplementation significantly increased serum glucose and cortisol in T1 and T2 (p<0.05). The current study results reveal that supplementation of diet with 0.5 and 1% WBMP causes negative effects on some blood and stress indices in juvenile Persian sturgeon. It seems that more studies are needed to determine the role of WBMP in sturgeon health and nutrition.

The aim of this study is to develop different models of aquatic forecasting and try to predict yellowfin tuna catch in the southern waters of the country with minimum possible errors. The average catch (Yi ± S. D) and logarithm of catch (LogYi ± S. D) for the years 1997 to 2021 were 35,378 ± 13,744 tons (95% confidence interval 21,634 - 49,129 tons) and 4.51 ± 0.18 tons (95% CI The confidence interval was 4.33-4.69 tons), respectively. According to the Mann-Kendall test, the average catch has increased significantly during the mentioned period (over the last two decades) (Z = 3.80, P < 0.05).  Different ARIMA combined prediction models (ARIMA, (p, d, q)) were tested based on the AIC index, and the ARIMA model (1, 0, 0) had the best fit with the change trend of yellowfin tuna in the southern waters of the country (AIC =- 24). The predict of yellowfin tuna catch results in the neural network (NN) models was show that feed forward neural networks (FFNN) have better performance than other models and with less error (MAE=0.02 and RMSE=0.03). Also, according to the results of ARIMA time series and neural network models, it can be concluded that feed forward neural networks simulate catch this species fish with higher accuracy than time series models. It seems, forecasting the trend of aquatic catch can be an important tool for fisheries managers and planners for better and sustainable management of aquatic resources and should be given more attention.

The present study aimed to investigate variability in growth pattern and evaluate abundance of A. persicus based on catch data in the southern Caspian Sea water in a period of 27 years (1991-2018). The data of 72704 specimens were analyzed separately by sex (male, female and population), time (years) and region (coastal waters of Gilan, Mazandaran and Golestan provinces). The highest catch of this species was recorded in 1991 (6038 pieces of the fish) and the lowest catch was recorded in 2018 (292 pieces). During the period, the Golestan province had the highest number of catches (30851 pieces) and Gilan province had the lowest ones (11129 pieces). The maximum recorded fork length of this species was 240 cm in 2006. The results showed that the highest annual average fork length was 151 cm in 2007 and 2010 and the highest annual average total weight in 1993, 1994, 1996, 1997 and 2007, which was 26000 grams. The lowest annual average fork length was 139 cm in 2018 and the lowest annual average total weight was 600 grams in 2010 and 2012. The highest length frequency corresponded for the ranges of 136-148 and 148-160 cm in males and females, respectively. The females showed the highest catches in 1991, and the lowest in 2018, while the males had the highest in 1991, and the lowest in 2014. The females dominated the population in the period of 1991- 2013, and after that this ratio was reversed. The allometric coefficient of growth (b) varied between 1.03 and 3.49 in the study period. The growth pattern was mostly positive allometric in first decade of study (1991-2001), isometric or negative allometric in the second decade of study period (2001-2011), and negative in third decade (2011-2018). During the study period, the condition factor of the fish varied between 0.61 and 0.80, and the average of the factor for the whole period of study was 0.72. Generally, the catch of A. persicus in the southern Caspian waters decreased more than 95% from 1991 to 2018 (a period of 27 catch-years).

Producing cost-effective aquafeed and using very available feed ingredients play an important role in sustainable aquaculture development. Such an undeniable necessity has resulted in special attention to local feed ingredients and application of biotechnological solutions to improve the ingredients. The present study was carried out to investigate the effect of various dietary contents of fermented canola meal with Bacillus sp. from sediments of the Caspian Sea on growth, liver antioxidative and metabolic enzymes activity of Nile tilapia fingerlings. 225 fish with an average weight of 1.9±0.05 g were fed five different experimnetal diets including, treatment 1 (control group): diet without fermented canola meal, treatment 2, diet containing 12.5% ​fermented canola meal, treatment 3, diet containing 25% fermented canola meal, treatment 4, diet containing 37.5% fermented canola meal and treatment 5, diet containing 50% fermented canola meal, for 8 weeks. Results revealed that the growth indices did not significantly differ among various experimental groups (p>0.05). Liver antioxidative enzymes activity showed that activity of SOD in treatment 4, and activity of GPX in treatments 3 and 4 increased compared to the control group (p<0.05). Although, activity of CAT did not significantly differ among various experimental groups (p>0.05), significant difference was observed between treatments 3 and 4 in this regard (p<0.05). Also, liver metabolic enzymes activity showed that AST activity of treatments 2, 3 and 4, and ALT activity of treatments 2, 3, 4 and 5 increased in comparison to control group (p<0.05). In general, it was concluded that incorporating 50% of fermented canola meal did not affect growth indices of Nile tilapia fingerlings.

Cephalopods have short life and global distribution except freshwater that these make them importance for study of their dynamics population. So, the purpose of this study was to estimate the biomass of cephalopods (Amphioctopus marginatus, Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvaucelii, Sepia saya, Sepia prashadi, Sepia omani, Sepia stellifera and Sepia pharaonis) with the catch dynamics model (generalized depletion model) in the NE Gulf of Oman at the end of the fishing season (of bottom trawlers) in the summer and autumn of 2020. The catch data of these valuable fisheries species were obtained through field sampling from commercial fishing in the depths of 74-212 meters by an industrial bottom trawler for 17 consecutive days in the "Gowater-Pasabandar-Beris" fishing grounds (at least 12 nautical miles from the shoreline according to the new move-on rule). The highest total abundance and biomass belonged to Sepia pharaonis by 23431 individuals and 27005.78 kg. Also, the lowest total abundance and biomass belonged to Uroteuthis (Photololigo) edulis by 8 individuals and Sepia saya by 0.397 kg, respectively. The abundance response for most of the stocks was a hyperdepletion (β > 1), while the fishing effort response for most of them was an effort synergy (α > 1). Also, most of the selected models were executed in the presence (open population) of perturbations (pulses). Cuttlefishes had the highest and octopuses had the lowest biomass, respectively. Probably, this study was the first survey of biomass for mentioned species in the waters of the Islamic Republic of Iran - except Uroteuthis(Photololigo)duvaucelii and Sepia pharaonis. The advantages of implementing catch dynamics model based on commercial fisheries activities are practical, operational, and close-to-reality estimates, lack of some costs of scientific surveys, also lack of additional pressure on aquatic resources (especially in nursery grounds) due to the implementation of fisheries activities (fishing operations) within the permitted limits (spatial-temporal).

Phloretin is a natural flavonoid that has antimicrobial and antioxidant activities. Gallic acid is another combination of flavonoids group. The object of this study was to evaluate the function of phloretin as a preservative factor for rainbow trout fillets during storage temperature in the refrigator. This performance has been investigated by examining microbial, chemical and physiochemical indices in four sampling times on days 0, 7, 14 and 21. Trout samples were dipped in phloretin solution (150 mg/ml and 250 mg/ml) and gallic acid solution (250 mg/ml), stored at 4°C for 21 days. Microbial tests showed that microbial load of trout fillet treated by phloretin 250 mg/ml lowered significantly (P<0.05) compared to the control samples in 0, 7 and 14 days. In addition to, phloretin significantly (P<0.05) reduces oxidation, total volatile basic nitrogen (TVB-N), hydrolysis of free fatty acids and the range of pH changes, which are chemical indicators of trout fillet spoilage in 0, 7 and 14 in comparison with control treatment and  also the analysis of the color indicators performed on the treated fillets, showed that phloretin 250 mg/ml was able to maintain color indexes compared to control samples at a significant level of 0.05 in 0, 7 and 14 days. All rainbow trout fillets were treated from day 14 had symptoms of spoilage. The results of this experiment proved the effectiveness of phloretin 250 mg/ml on antimicrobial mechanisms, and inhibition of spoilage.