yaghobali zahmatkesh

Three species Rutilus frisii, Alburnus chalcoides and Vimba persa are the most valuable fish that migrate to southern Caspian rivers especially Sefidroud river. In this study, the temporal and spatial distribution of was investigated based on presence and abundance of fingerling fish in 8 stations of the Sefidroud River, from the estuary to the Sangar Dam, during one year from March 2021 to December 2022.</span></span></span> According to the environmental conditions of stations, the sampling was done with an electrofishing instrument and a throwing net with mesh size 6 mm. The results showed that the abundance of fish fingerlings is minimal in the winter and their maximum abundance coincides with the reproduction time and after their adult spawning. The maximum abundance of these fingerlings along with their spatial distribution, also shows their migration pattern towards the Caspian Sea. The abundance of Rutilus frisii in the pebble and gravel beds of the upstream stations was the highest in April and the abundance of the Alburnus chalcoides and Vimba persa in the gravel-mud beds of the middle stations up to the estuary was the highest in August-September. The presence of Rutilus frisii fingerling, with an average weight of 2 g. was high in near to estuary in August while the other two species were present in the middle stations with high abundance until November. Rutilus frisii with weigh more than 3 grams in different stations in autumn and winter indicate the adaptability and residency of a number of fish in the river. The present study can provide some guidelines to the fish stocks restoration centers of Caspian Sea for releasing Kutum fry in the upstream areas, or fish fingerling in the middle of the river at an earlier time. This plan can be tested in a pilot program.

More than 50 fish species exist in Guilan coast waters and 20 species of them are economic, but there is few data about their fingerlings. This study has been done in Talesh, Anzali, Kiashahr and Chaboksar shores and fish seasonally caught by beach seine with 8 mm mesh size from winter to autumn 2021, and the main purpose was determining fish abundance in Guilan province coasts, too. Results showed 32 fish species belong to 13 families in studied are and Leuciscidae family was the most diversified with 8 species. The study of fish abundance showed dominancy of Chelon saliens, Alburnus chalcoides and Atherina caspia with 42.5%, 18.1% and 11.6% in Talesh shore, A. chalcoides, C. saliens, and A. caspia with 25.1%, 22.1% and 20.8% in Anzali shore, C. saliens, Rutilus frisii and A. chalcoides with 31.8%, 17.4% and 14.8% in Kiashahr shore and C. saliens, A. chalcoides, Neogobius pallasi and chelon auratus with 29.9%, 21.5%, 14.2% and 10.5% in Kiashahr shore, of total count (number), respectively and they were predominant. In general, were abundant fish, the fingerlings to non-adults of sharp-nosed grey mullet (Ch. saliens) and Shemaya (A. chalcoides) in all stations, Caspian silverside (A. caspia) in 2 stations and fingerlings of Golden grey mullet (Ch. auratus) and Kutum (R. frisii), and fingerlings to adults of Caspian sand goby (N. pallasi) in one station, that show a more adaptation of these species to environmental conditions in 4 studied stations. The continuous monitoring of density of small size individual of fish species in southern coasts of Caspian Sea is essential for conservation of their populations.

More than 70 millions of Kutum (Rutilus frisii) fingerlings are released in the rivers of Guilan province annually for restoring, but there is few data about biological chracteristics about the fish during staying in the rivers downstream, thus this study has been done on abundance, growth, condition factor and diet of released fingerlings of kutum fish (Rutilus frisii) in Khoshkrud River downstream, and for this propose, 3 stations selected in the river downstream and sampling has been done using electroshocker monthly from Oct. 2022 until March 2023. Results showed Alburnoides samii, Capoeta razii, Rutilus frisii, Ponticola gorlap and Cobitis with 249.2, 108.7, 85.2, 32.2 and 31.4 individuals in 100 m2 catch effort had the most abundant. The fingerlings of kutum fish present in all months in the river downstream and its density varied 20.0 to 212.5 individuals per 100 m2. Studied fingerlings (n=119) had a weight of 2.10-15.10 (5.77±2.54g, average±s.d), total length of 6.62-12.20 (8.61±1.13cm) and condition factor 0.71-0.97 (0.86±0.05) and there was significant statistical difference only in condition factor between autumn and winter. The length-weight parameters was calculated for b-value 3.09 and correlation coefficient (r2) 0.98 and indicated isometric growth patterns. It was determined vacuity index 40.9% and 59.6%, the mean relative length of intestine 0.78±0.08 and 0.75±0.08 and the mean fullness intensity 76.1±97.1 and 71.3±118 in kutum fingerlings in autumn and winter seasons, respectively. There was 6 macro-invertebrates and 14 genera of algae in gut of kutum fingerlings and in the fish intestine were abundant Chironomidae from benthos and genera Synedra, Navicula, Diatoma and Melosira from algae cells in both seasons. In general, fullness intensity, condition factor and water temperature were no suitable for staying fish fingerlings in the stuied duration, but was not distinguished the reason of settle of fish in rivers and no emigration to sea water.

About 30 species of commercial fish have been caught in the seawater of Guilan province annually and the most important species is Kutum (Rutilus frisii). The aim of this study was to determine the feeding indices, food spectrum, and dominant food items of fingerlings kutum under the investigation of feeding habits of kutum and grey mullets on the coasts of Guilan province. The fish were captured with a seine net with 6 mm mesh size from winter 2020 to autumn 2021 in the coastal areas of Talesh, Anzali, Kiashahr, and Chaboksar. The results on R. frisii with body weight 0.31-14.5 (3.64±2.8)g, total length 34.3-120 (68.3±19.0) mm and ages 0+ and 1+ years showed that the relative length of intestine is 0.59-1.16 (0.78±0.10). Vacuity index was calculated at 0, 0, 5, 0 and 1% in spring, summer, autumn, and winter seasons and the total of the year, respectively, and the mean fullness intensity was 372±267, 360±151, 230±173, 581±689 and 365±302 in spring until winter and total of the year, respectively, which showed significant differences (F=9.10, p<0.05). Detritus, filamentous algae, 26 genera of phytoplankton, 2 types of zooplankton and 13 types of benthic animals and as well as eggs and larvae of fish were observed in the gastrointestinal tract of kutum fingerlings with a frequency of presence 10, 73, 62, 5, 86 and 2 percent of all studied specimens, respectively. The phytoplanktonic genera of Cyclotella, Navicula and Nitzschia were observed in 60%, 52%, and 47% respectively, and gammaridae among the benthic animals had the most frequency in 68% of the fish. In general, according to the feeding indices, feed diversity, and dominance of feed items, kutum fingerlings are a benthic feeders and euryphagous with a good fullness intensity on Guilan coasts.

Silver carp, Hypophthalmichthys molitrix, is a plankton filter feeder fish and introduced to Chitgar Lake since 9 years ago. In this study, the effect of silver carp stocking was evaluated on the phytoplankton structure of Chitgar Lake at different seasons in 2018. Samples were caught with gill-net, beach seine and cast-net gears. The results obtained from 51 individuals with a total length of 111-473 (average total length of 325.8±134.6) mm showed that coefficient of vacuity, averages of relative gut length and feeding intensity were 0.00%, 5.91±1.65 and 628.4±274.7, respectively and therefore it showed over eating, herbivory and good feeding intensity in this fish. Silver carp fed on 32 phytoplankton and 11 zooplankton genera and phytoplankton and zooplankton were observed in 100% and 88% of studied specimens, respectively. Synedra, Navicula, Staurastrum and Cyclotella were the dominant phytoplankton genera (30.0, 22.2, 13.8 and 12.1%, respectively) and Bosmina and Alona were the dominant genera of zooplankton (84.0 and 7.2%, respectively). There were no seasonal changes in feeding intensity but there were seasonal changes in food items dominance. Releasing of 20000-30000 individuals of silver carp with a weight 50-100 g is suggested in order to protect water quality of Chitgar lake annually.

Some reproductive characteristics of the non native oriental river prawn Macrobrachium nipponense were monthly studied in Anzali Wetland. Totally more than 2,500 prawns were caught and examined during this period, with maximum and minimum lengths of 97 and 10.05 mm and weight of 0.02 to 13 g, respectively. The average length of shrimp was 45.7±14.3 mm and the mean weight was 1.4±1.376 g. The sex ratio of females to males was 1.1±0.4 on average, which during the peak spawning months, this ratio is more inclined to females. Examining some of the reproductive factors of 244 ovigerous females within the length of 38 to 92.7 mm with an average length of 56.8±8.2 mm showed that the most frequent length and weight classes were 50 to 60 mm in length and 2 to 3 grams in weight, respectively. The minimum oviposition length was 38 mm. Total fecundity was observed 75 to 4146 oval eggs with short diameter 0.35 to 0.8 mm and long diameter 0.5 to 1.0 millimeters. The number of eggs hatched by shrimp was linearly correlated with total length and weight of shrimp. Reproductive efficiency ranged from 0.01 to 0.19. Although its fecundity is lower than other economical species of Macrobrachium, other characteristics such as reasonable reproductive output and long reproduction period can make them suitable option in aquaculture.

The Anzali Wetland is one of the most important water bodies in Iran, due to the Caspian migratory fish spawning, located in the southern Caspian Sea basin, Iran. During a long-term monitoring program, between 1994 to 2019, identification and distribution of fish species were surveyed in five different locations inside the Anzali Wetland and eleven related rivers in its catchment area. In this study 72 fish species were recognized belonging to 19 orders, 21 families and 53 genera, including 66 species in the wetland and 53 species in the rivers. Among the 72 identified species, 34 species were resident in freshwater, 9 species were anadromous, 9 species live in estuarine and the others exist in different habitats. These species include 4 endemic species, 50 native species and 18 exotic species to Iranian waters. The number of species in different locations inside the Anzali Wetland was comparatively similar while it had high variation in different rivers. Twenty fish species are new records for the Anzali Wetland basin, including 10 estuarine, 5 ornamental, 2 riverine, one anadromous, one euryhaline and a small exotic fish.