نشریه پژوهش های ماهی شناسی کاربردی
سال دهم شماره 3 (پاییز 1401)

Hilsa shad (Tenualosa ilisha Hamilton, 1822) is a migratory fish and as one of the most important species in the southern parts of Iran, so that during the last decade, the amount of its catch has fluctuated a lot. Due to the limited data available on the stock of this species in southern waters, it is not possible to use models based on complementary data to assess its stock. In the present study, to determine the stock status of Hilsa shad in southern waters, the catch-maximum sustainable yield (CMSY) model was used. Catch data from1997 to 2019 were collected and entered into the model to calculate fisheries reference points. The value for B/BMSY by the model was estimated to be less than 1.0 and the value of F/FMSY was more than 1.0, which indicates the critical situation of this species in the southern waters of Iran and that the stock is under fishing pressure. Based on the obtained fisheries reference points, the MSY was estimated as 4,360 Mt which due to high fishing pressure and depletion of stock that has occurred during these years, in the years after 2012, has never reached to this amount of catch and, the amount of catch has been less than the MSY. Considering that more than 92 percent of the catch of this species is done in the waters of Khuzestan province, so the management strategies for applying restrictions in the fishing effort and fishing licenses for traditional fishing vessels should be mainly concentrated in this area and it is recommended to stop fishing of this species so that the stock could find the opportunity to rebuild.

Dynamic energy Budget (DEB) theory describes the rate of energy absorb by living organisms and use it for body protection, growth, and reproduction. The present study was performed on Alburnoides eichwaldii in Zarrin-Gol and Kaboudwal rivers (Golestan province). The results showed that the DEB growth model in the two rivers and the allocation of energy fraction for body maintenance (κ) was more than 0.9, which indicates the high growth rate and short lifespan of this species. Maximum surface specific-area assimilation rate {pAm}  in Kabudwal river fish is about three times that of Zarringol River. Somatic maintenance based on body volume, pM  for Zarringol River is about 3 times and the maximum reserve density[Em]  is about 5 times less than Kabudwal. In Addition, maturity at birth EHb , In Zarringol river was less than Kabudwal and maturity at the time of reproduction EHp  in Zarringol river was more than Kabudwal but its size was bigger at maturity in Kabudwal river. On the other hand, the higher energy conductivity ϑ in A. eichwaldii in Zarringol River was due to its low energy density, and this fish in Zarringol River needs less energy to somatic maintenance. The DEB standard model is superior to other models in that it is able to provide quantitative and measurable descriptions for the aspects of individual and population metabolism of animals.

For more than two decades, assessment and monitoring of Oman Sea demersal resources has been carried out using swept area method. The study area starts from western water of Iran to border of Iran and Pakistan in the east of Oman Sea and total study area were divided into 5 sub-areas M to Q in different depth layers of 10-20, 20-30, 30-50 and 50 -100 meters. In general, the average amount of biomass has a downward trend in different depths of 2003 to 2021 years. Due to the changes in the average biomass at different depths, it can be said that the average biomass at depths of less than 20 meters has decreased. Average biomass of depths less than 20 meters have decreased significantly from about 14 thousand tons in 2003 to about 1.5 thousand tons in 2021 (P<0.05), and benthic biomass accumulation has shifted from coastal and shallow areas to deeper areas. Also, average catch per unit area of different areas had a decreasing trend in 2003 to 2021 and usually regions O and Q had higher values than other regions in different years (P <0.05). Some species fish such as Otolitus ruber, Lethrinidae, Ray and sharks have decreased sharply and some species fish such as Nemipterus japonicus, Saurida tumbil and Sphyraena sp. have increased in fishing composition. Considering the mentioned conditions, it seems that the amount of demersal resources caught is not in a good condition and measures should be taken to reduce the catch of these fish.

The present study was conducted to compare the growth indices and blood factors of sterlet (Acipenser ruthenus), Siberian sturgeon (Acipenser baerii) and their hybrid (Acipenser ruthenus ♀ × Acipenser baerii ♂) to produce a fish with larger size, larger eggs and more tolerant to environmental conditions than the parents. The hybrid was produced by mixing of the oocytes of one sterlet female with the sperm of a Siberian sturgeon. For this study, 75 juvenile Siberian sturgeon with a mean weight of 32.38 ± 0.36 g, 75 sterlet with an average weight of 32.38 ± 0.41 g and 75 hybrid with an average weight of 32.37 ± 0.41 g each with 3 replicates were distributed in 9 concrete ponds with a volume of 800 liters and reared for 10 weeks. Thirty days after the start of rearing, the growth of juveniles hybrid was significantly higher than that of sterlet (P < 0.05). By continuing to feed the fish until the end of the 72-day study period, hybrid growth was still significantly higher than that of sterlet, but not significantly different from Siberian sturgeon (P > 0.05). The amount of feed intake, weight gain, specific growth rate, and percentage of body weight gain in hybrid were significantly higher than the sterlet (P < 0.05). These indices were lower in hybrid than the Siberian sturgeon but were not significantly different (P > 0.05). The feed conversion ratio of hybrid was significantly lower than that of sterlet (P < 0.05), while no significant difference was found with Siberian sturgeon (P > 0.05). Except for total protein and mean corpuscular hemoglobin, the other hematological indices showed no significant differences among the fish (P < 0.05). The mean corpuscular hemoglobin in hybrid was higher than compared with Siberian sturgeon and sterlet and (P < 0.05). The sterlet × Siberian hybrid showed similarity to the Siberian sturgeon in terms of growth indices, which indicates that it has the characteristics of Siberian sturgeon that has a better growth rate than the sterlet. In terms of blood parameters, the hybrid showed the characteristics of both parents.

Extensive lack of data and information gaps for recreational fishing necessitate knowledge of the species caught to establish aquatic reserve management. Therefore, in the present study in 2021, by collecting lenght and weight information of major recreational fishes in the main recreational fishing area was done with hooks. The results showed that between the length and weight of common carp in Golestan, Mazandaran and Golestan provinces, the equations were 0.444004x4004 and 0.4652/168x2/4652 with a correlation of 90%, 95% and 94%, respectively. Between the length and weight of grass carp in Golestan, Mazandaran and Golestan provinces, the equations 0.2398x2 / 2398 and 0.6333x2 / 1313 and 30.3x1 / 7769, respectively, with a correlation rate of 96%, 94% and 90% were established and between the length-weight of yellow fish in Golestan, Mazandaran and Golestan provinces were equations of 0.494x3 / 113, 1101x1 / 4615 and 982x1 / 1381, respectively, with a correlation of 89%, 90% and 97%. The results showed allometric growth of all three species in all studied provinces. The allometric growth rate of common and yellow carp was positive in Golestan province and negative in Guilan and Mazandaran provinces. Allometric growth rate of herbivorous carp was negative in all studied provinces .

The present study was performed to evaluate the protective effect of molasses pretreatment on the liver index of common carp (Cyprinus carpio) in exposure to copper oxide and titanium nanoparticles. Therefore, 250 juveniles of common carp for 42 days in four categories, rations without molasses (treatment 1), diets containing 0.5% molasses (treatment 2), diets containing 1% molasses (treatment 3) and diets Containing 2% molasses (treatment 4) were divided. Then, 50% of the lethal concentrations of copper and titanium oxide nanoparticles were added to each group for fourteen days. Histological studies of fish exposed to molasses and oxidomes and titanium nanoparticles showed structural abnormalities in liver tissue such as hemorrhage, fattening, and macrophage accumulation. So that these changes were very different compared to the tissues of the control group. The final conclusion of the present study showed that nano-titanium and nano-copper treatment resulted in tissue damage in carp liver; Although pathological complication was also observed in the combined treatments of the mentioned nanoparticles and molasses, but the severity of injuries decreased with increasing molasses concentration.

The current research was conducted in 2021 in 5 stations in order to investigate the quality of water before the operation of Javeh Dam in Kurdistan Province. Sampling of fish and Macrobenthos was done using an electrofishing device and Surber sampler, respectively. A total of 13 fish species were identified, which belonged to 3 families: Cyprinidae, Mastacembelidae and Nemachielidae. Out of the total of 2003 fish caught in all the stations, more than 96.6% belonged to the Cyprinidae family. The highest relative frequency of 32.4% belonged to Capoeta damascina species. In addition, 2 exotic species, Carrasius auratus and Carrasius gibelio had an abundance percentage of 1.4. The diversity of fish species decreased from station 1 (upstream) to stations 2 and 3, which was probably influenced by human activities such as various types of pollution, but in station 5 of It had the maximum amount, which is due to the change in habitat conditions, such as the increase in flow rate and water depth. The results showed that the species diversity of fish had changes in different seasons, so that its minimum was estimated at 0.91 in winter and its maximum at 1.29 in summer. Macrobenthos included 10 families Chironomidae, Lumbriculidae, Simulidae, Baetidae, Hydropsychidae, Erpobdelidae, Glosiphonidae, Gamphidae, :union:idae and Potamidae. The classification of water quality based on the Karr ecological integrity showed that stations 1 and 4 were placed in the good quality class with a numerical value of 40 and 42, respectively, and stations 3 and 5 were placed in the very low and medium water quality classes with a numerical value of 9 and 34, respectively. In this way, it is necessary to manage and organize all sources of point and non-point pollutants in Gheshlagh and Gavehroud tributaries.

In the present study histological effects of copper and Zinc sulphate on, 250 Caspian beluga (Huso huso) fingerlings were studied. In this regard, fish of treatment groups were exposed to 0.1, 0.2, 0.4, 0.6, 0.7 and 0.8 mg/l of copper and 5, 25, 50, 75, 80 and 85 mg/l of Zinc sulphate during 4 days respectively. Behaviours and clinical signs of fish were recorded during the experiment. Samples were cut from kidney, liver and gill of moribund and fresh dead fish for histopathological signs. Then, specimens were studied after section and hematoxylin- Eosin staining. On the present study, LC50 value for 96 hours exposure were calculated as 0.52 and 54.21 mg/l, respectively for Copper and Zinc. Mild to severe histopathological signs were observed in kidney, liver and gill of all treatment fish specimens. Pathologic severity signs in sampled tissues were increased by increasing in concentration and exposure times of copper and Zinc sulphate.