نشریه پژوهش های ماهی شناسی کاربردی
سال دوازدهم شماره 3 (پاییز 1403)

In this study, length frequency, length-weight relationship and length of sexual maturity of skipjack tuna (Katsuwonus pelamis (Linnaeus, 1758)) caught by surface drift with the meshes size of 145, 165 and 197 mm gillnets in the coasts of Sistan and Baluchistan province from October 2019 to June 2020 Was investigated. The results of measuring 719 fish caught from different meshes showed that the fork length range is between 46 to 80 cm (Mean±SD 55.87±6.22 cm) and also their weight range varied between 1980 and 10820 g (Mean±SD 3811.71±1656.25 g). The lowest amount of fork length in October and the highest amount in June was obtained and the relationship between fork length and weight of K. pelamis was W= 0.0066FL3.2853 with R2 = 0.9706. Also, the results of t-test showed that there was a significant difference between the value of b number calculated with isometric growth index (b= 3) (P< 0.05) and therefore the growth of K. pelamis was determined to be positive allometric. The Lm50 index was estimated by the least squares method at 45.3 cm in the fork length. The results also showed that immature fish were not caught in all the meshes used and these meshes are unobstructed for this species.

This study examines the trends in Istiophoridae catch and the impact of environmental factors in the western Indian Ocean from 1999 to 2019, utilizing a Generalized Additive Model (GAM). The findings reveal a significant decline in annual catch levels, influenced by climate change and the El Niño phenomenon, particularly between 1999 and 2009. However, post-2009, improved environmental conditions and the implementation of effective management policies have contributed to a recovery in catch levels observed as early as 2012. The GAM analysis identified sea surface temperature, surface wind speed, and sea surface salinity as the primary variables affecting Istiophoridae distribution. Furthermore, the study assessed the effects of temperature and salinity on fish abundance, determining that optimal biodiversity is achieved at temperatures between 25 and 290C and a salinity level of 35 ppt. This research highlights the critical importance of continuous monitoring of environmental variables and the necessity for sustainable marine resource management. Such efforts are vital for preserving biodiversity and improving fishery conditions. The outcomes provide a foundational basis for developing effective management strategies aimed at the conservation and sustainable utilization of marine resources.

This study aimed to investigate the growth and mortality parameters rates and the reproductive biology of T. vitrirostris on Hormozgan inshore waters (the northern Persian Gulf). 1211 specimens were selected by Stake-Nets, shrimp trawling fisheries, Trichiuridae in Qeshm Island located in the Persian Gulf during January 2010 to December 2010. 260 specimens was obtained to determine the sex ratio. growth parameters obtained from otolith ageing and length frequency analyses with FISAT and ELEFAN1method agreed well. The minimum and maximum length of the fish specimens were calculated 2/3 cm and 24.4 cm and length-weight 0.2g and 78.8 g, respectively. The a value of the length-weight relationship was obtained 0.0047 and for b was 3.121 that showed positive allometric growth. Estimated Von Bertalanffy growth parameter values were (L∞ = 23.42 cm, K = 0.62 and t0 = -0.279 year) and (L∞ = 25.12 cm, K = 0.41 and t0 = -0.421 year) for male and female, respectively. Also infinity weights (W) were estimated nearly to 17.563. The annual total mortality, fishing mortality, and natural mortality coefficients were estimated 2.138, 1.118 and 3.256 per year, respectively. Also, the exploitation coefficient 0.656 was obtained, which indicates that the stock was not overexploited.

The aim of the present study was to investigate the effects of Nostoc algae on the growth indices of Siberian sturgeon (Acipenser baerii). A total of 72 juvenile Siberian sturgeon with an average weight of 140 ± 4 grams were allocated to four treatment groups, each with three replicates. The treatments included a control diet (without algae extract), treatment one with 0.5% extract, treatment two with 1% extract and treatment three with 2% extract of Nostoc algae. The fish were fed over a period of 42 days. Biometric measurements were taken both at the beginning and at the end of the experimental period to evaluate the growth indices. Data analysis at the end of the experiment revealed that specific growth rate (SGR) and weight gain (WG) were highest in the 2% algae treatment, while the control group had the lowest performance. The highest feed conversion ratio (FCR) was achieved in the control group, while the lowest FCR was observed in the 2% algae group. The best condition factor (CF) was recorded with the 0.5% algae treatment, while the lowest CF was associated with the 1% algae treatment (P < 0.05). Overall, these results indicate that the addition of Nostoc algae at different percentages significantly improved the growth indices of Siberian sturgeon. Based on the research results and the knowledge gained from the different treatments, the use of nostoc algae at a concentration of 2% seems to be the best option to improve the growth indices of Siberian sturgeon (Acipenser baerii). This treatment showed the highest growth and body weight gain compared to the other treatments. In addition, the treatment with 0.5% nostock algae seems to provide the highest condition factor (CF). However, in terms of weight gain and overall growth, the 2% treatment shows clear superiority.

This research aims to determine the physiological effects of the natural antioxidants of olive oil and the synthetic antioxidant of butyl hydroxytoluene (BHT) by studying the fatty acids of the diet and carcass and determining the food shelf life indicators (TVN and peroxide) in Persian sturgeon (Acipenser persicus) breeding was done. For this purpose, 315 juvenile fish with an initial weight of 108 ± 0.02 gr were selected and stored in seven treatments after acclimatization to the brackish water of the Caspian Sea. Three dietary treatments with concentrations of 1, 3, and 5% of olive oil and three other treatments with concentrations of 100, 150, and 200 mg/kg of diet from BHT and the control treatment without olive oil and BHT were fed to the fish, and each treatment with three repetitions for two months. The results showed that the fatty acids levels of diets containing olive oil and fish carcasses that used these diets had significant differences compared to diets containing BHT. The results of food shelf-life indicators showed that the shelf life of diets containing 1% and 3% olive oil increased. Based on the results, the amount of TVN decreased in all treatments compared to the control. However, the lowest increase in TVN was observed in treatments 1 and 2 (56.9 ± 0.38 and 59.8 ± 0.23 meq/100 g), respectively; which was significantly lower than the control and other treatments. The amount of peroxide in the control and treatments 3 and 6 was significantly higher than other treatments; But the lowest amount of peroxide was observed in treatments 4 and 1 (6.8 ± 0.17 and 7.23 ± 0.21 meq/1000 g), respectively, which was significantly less than the control and other treatments. In general, adding the natural antioxidant of olive oil 1 and 3% to the diet increased the shelf life of the diet and preserved the carcass quality of juvenile Persian sturgeon, and its addition to the diet is recommended.

This study was conducted with the aim of investigating the effect of different levels of thyroxine hormone in rearing water and diet on survival and some mucus immunity indicators in the early stages of growth of rainbow trout. The experiment was carried out in three stages: hatched eggs until complete hatching, hatched larvae until active feeding, and active feeding until weighing about 1 gram of fry fish. In each stage, the experiment was performed in three concentrations of thyroxine solution (0.03, 0.06 and 0.09 mg/L) along with the control group (without thyroxine hormone) with 3 repetitions. Thyroxine was added to water in the first and second stages and to food in the third stage. At the end of the third stage, survival and some mucus safety indicators were investigated. The results showed that the highest survival rate was obtained in the treatment 9 with 98.67 ± 1.33. The immune indices of total protein, immunoglobulin and lysozyme showed a significant difference compared to other treatments (p<0.05). The highest amount of protein (2.08 ± 0.18 mg/ml), immunoglobulin level (0.65 ± 0.09 g/dL) and lysozyme level (1.90 ± 0.02 μg/ml) were recorded in the treatment.9. According to the present study, thyroxine hormone has led to positive effects on survival percentage and some safety indicators in rainbow trout fry.

This Study was conducted to determine the growth characteristics of Caucasian species (K. caucasica) in Gorgan Bay and Gomishan wetland. 149 specimens from Gorgan Bay and 192 specimens from Gomishan wetland were collected from February 2013 to May 2014 using beach sein. The length of samples range from 07.07 to 39.41 mm and weighing from 0.01 to 0.84 gr, and 48/15 to 44/78 mm and weighing from 0.05 to 1.0 gr in Gorgan Bay and Gomishan wetland. The age of the specimens was determined by Otolith and the ranges from + 0 to +1 in the Gorgan Bay and +0 to +2 in the Gomishan wetland. The b value in the Gorgan Bay for males 3.07-3.32, for females 3.31-3.3.69 and for male 3.16-3.43 and for female 3.19-3.45 in Gomishan wetland. The growth pattern of this species was positive allometric for both sexes in Gorgan Bay and Gomishan wetland. The highest condition factor in Gorgan Bay for male and female was observed in March, and in Gomishan wetland, in May and February, respectively.

This study was conducted for estimation growth of R. kutum from October 2023 to March 2024 in fishing grounds of Hormozgan province. A total of 286 specimens were weighed and measured. 149 samples, including 65 males and 84 females, were transferred to the University of Sari and Gonad laboratories for evaluation age and gender. Length-frequency distribution of both sexes had significant differences. The Exponential relationship between Fork length and total weight were estimated of population, males and females were as W=0.0045L2.947and W=0.0191L2.894 and W = 0.0076L3.154 respectively. Age at length data were used for evaluated parameters of K and L∞ By Goland and Holt equation. K and L∞ for population male and female were calculated of R. kutum, were calculated 0.179 year-1 and 62.84 cm, 0.23 year-1 and 52.25cm, 0.164 year-1 and 64.16 cm respectively. Tmax of R. kutum for population, male and female were estimated, 15.38, 12 and 18.29 year respectively. Phi Prime ф index of population, male and female were estimated 2.94, 2.79 and 2.82 respectively. W∞  for population, male and female were estimated, 3619, 2011 and 3807gr respectively.