نشریه پژوهش های ماهی شناسی کاربردی
سال نهم شماره 4 (زمستان 1400)

This study aimed to investigate the changes and growth pattern of Persian sturgeon fishing in fishing regions of Golestan and biological characteristics of this species over a period of 10 years. The highest amount of Persian sturgeon fishing was in 2012, when a total of 143 pieces of this species were caught from five fishing grounds in Golestan province, and the lowest amount was caught in 1398, when 49 pieces of this species were caught. in the present study, the maximum total length of Qarabrun was in 1397 with a total length of 257 cm. Mianqaleh fishing farm had the highest number of catches (471 pieces) of this species and the lowest amount of catches (26 pieces) for this species was recorded in Chalasht fishing farm. The results showed that the highest average total length was observed in 2014 and the highest total weight was observed in 2017 and the lowest average total length and total weight was obtained in 2012. The sex ratio of males to females of Persian sturgeon species in the ten-year period was 1.24: 1, where the male population was higher (p < 0.05). The range of growth coefficient (b) for the population of Persian sturgeon in the years 2011 to 2020 varied between 2.60 to 3.82, The results of Pauli test for the relationship between length and weight of Persian sturgeon species showed that the growth pattern of this species in 2011 and 2012 was negative allometric, in 2015 positive allometric and in 2013, 2014,  2016, 2017, 2018, 2019 and 2020 It was isometric. Conclusion of this study shows that in a period of 10 years for Qarahbrun species had a decrease of 75%, so in the waters of Golestan province this trend for Qarahbrun is among the most endangered species and this means an alarm for this valuable species It has been heard in the Caspian Sea.

In this study, age and growth parameters of Prussian carp C. gibelio were examined using 247 specimens catched from the Goletan dam lake and 208 specimens from the Voshmgir dam lake. Sampling was carried out monthly over the period of February to September 2015. Total size distribution varied from 41 to 196 mm in length and 1.25 to 141.35 g in weigh and from 44 to 240 mm in length and 1.73 to 280.6 g in weigh in the Golestan and Voshmgir dam lakes respectively. Length-weight relationship of population was calculated as W = 0.021 TL2.92 in Golestan dam lake and W = 0.027 TL2.79 in Voshmgir dam lake. The parameters of von Bertalanffy growth fit the mean observed total lengths-at-age for each sex separately and were estimated as L∞= 378.09 mm, k = 0.12 year -1, t0= -0.43 year for females, L∞= 309.38 mm, k = 0.17 year-1, t0= -0.02 year for males, and as L∞= 355.74 mm, k = 0.13 year -1, t0= -0.35 year for combined sexes in the Golestan dam lake, L∞= 408.70 mm, k = 0.52 year -1, t0= -0.20 year for females, L∞= 186.23 mm, k = 0.51 year-1, t0= -0.42 year for males, and as L∞= 302.94 mm, k = 0.04 year -1, t0= -0.73 year for combined sexes in the Voshmgir dam lake.

The purpose of this study was to explore the feeding habits and preference prey of Sphyraena jello in Chabahar marine waters between April 2019 to March 2020. The number of 385 specimens with mean (±SD) total length and weight 64.0±3.5 cm and 925.45±12.0 g for males and 66.0±2.45 cm and 1001.35±5.2 g for females were examined. Length-weight relationships of male and female was respectively computed W=0.021L2.752 and W=0.017L2.823. For males, the maximum and minimum ISF% was observed in February (with 37.22%) and August (75.18%). Against, it was 18.01% and 84.75% in August and January for female. Mean (±95% CL) vicinity index (CV%) was calculated 15.90±12.79 (for male) and 7.84±2.55 (for female), which are indicated S. jello is a full-feed species. Fifteen food items were recognized which the maximum and minimum FO% were related to Clupeidae (with 25.48%) and Cuttlefish (with 1.49%). Small-pelagic fish (Sardins and Anchovis) were the most important food items (with more than 50%) of this species, totally. Considering ecological importance of S. jello, these result could provide useful information for fish biologists and stock assessment and fisheries management researchers.

This investigation was conducted to study of diversity and distinction of Garra rufa in some aquatic ecosystems located in Fars province. So, 208 samples were collected from five aquatic ecosystems located in Fars province (Rudbal river, Babasheikh Khalil subterranean, Qaderabad subterranean, Doudabad subterranean, Khargheh river) and 24 morphological traits were measured. Before data analysis, morphometric traits were standardized to reduce or eliminate of size and algometric growth effect. The results showed that studied population have significant differences in all of relative morphometric traits except of pelvic fin length, which indicates a high phenotypic diversity in Gara. According to principal component analysis, population of Babasheikh Khalil are very different with Qaderabad and Kharqeh population. On the other hand, a little separation was observed for Kherghe and Rudbal populations with Qaderabad and Dodabad. Based on results, the most important traits for identification and differentiation of G. rufa population are dorsal fin height, anal fin height, barbell length, disc length and disc width in the studied ecosystems.

Despite the reported effects of egg vitellogenin-derived proteins (VtgDP) and amino acids on embryo-larvae viability in common dentex the effects of non-vitellogenin-derived proteins (non-Vtg-DP) has yet to be determined. As an initial study, fertilized eggs (70 batches) were provided by natural spawning of broodfish in captivity. Viability parameters (VP) such as egg floating, hatching, and larval survival rate were calculated. Egg batches were categorized as low, medium, and high quality upon hatching rate. Based on the SDS-PAGE of egg crude extracts 63 protein bands (16.7 to 131.4 kDa) were identified. The intensity of bands on gel (densitometry; <200 to 877 μg mL-1), and their biochemical nature (specific staining) was determined. After subjecting the bands to a screening process, 11 bands were considered as non-vtgDP-contained bands. The highest intensity of the bands was observed in the gels belonging to high quality eggs. The intensity of 9 bands of 11 (individually or in combination with other protein bands) was significantly (p<0.001) and positively correlated to VPs via a series of simple and multiple regression models. In brief, the preliminary results revealed the importance of the class of egg proteins and their effects (individual and combined) on the viability of common dentex larvae and indicated their probable potential use to predict egg quality in teleosts. It also showed that it is worth to conduct a deeper study for more detailed characterization of the protein content of the selected bands and to evaluate the mechanism of their effects on larval success

This study aims to investigate the morphological variety using morphological differences of otolith in two species of Bathygobius meggitti and Istigobius ornatus from gobiidae family and their populations in Makran coast, Southeast of Iran. In order to do this, 56 samples of goby were caught and collected from three stations of Tis, Lipar, and Big Sea during spring and summer of 2018. Right and left otoliths of species were taken out. Four landmark points on the maximum length and width of otolith growth and 128 semi-landmark points around otoliths were digitized using professional software of geometric morphology, and R software was used to analyze them statistically. Results of analyzing semi-landmarks and real landmarks showed a significant intra-species and intra-population difference. The highest difference was observed in Tis population for both species, B.meggitti and I.ornatus. There was significant intra-species difference between two populations of Tis and Big Sea for B. meggitti species and a significant difference was observed between two populations of I. ornatus species in Tis and Big Seda. In addition, results of landmark analysis showed there was significant Intra- and inter-species difference in the size of otolith growth zone. Such information can improve our knowledge about the phylogeny and taxonomy of these species and help us to know the biodiversity.

This study was conducted to evaluate the performance of Gilan trawling cooperatives. In this research, the descriptive statistics and break-even analysis method was used and the data of this research were collected by using a questionnaire from trawling cooperatives for the fishing season of 1396. The results showed that the cooperatives of Rasht and Astara with the average of 111829 and 7710 kg, respectively, had the highest and lowest fishing performance and in total, in Gilan province, each cooperative had an average of 65839 kg of fishing. The average income and average cost of of fishing were 31528 and 12310 Tomans, respectively, and the average net profit per kilogram of fishing was 19218 Tomans. Despite the existence of two loss-making cooperatives, the average profit rate for all cooperatives surveyed was 203%. Also, the surveyed cooperatives had the least difference in terms of total cost and the largest difference in terms of net profit. However, according to the results of this study, higher (lower) revenue generation of cooperatives has not necessarily led to their higher (lower) profitability. Also, the correlation results showed that the amount of fishing has a strong and positive relationship with the average income and average profit and a strong and negative relationship with the average cost of fishing. In addition, the average breake-even point for all cooperatives was 21.6 tonns.

Feeding habits of Grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 in coastal waters of eastern Hormozgan province from Bandar Sirik to Bandar Jask were studied by sampling 30 fish per month throughout one year. Mean values of fish total length and fish weight was 101.04 ± 4.09 cm and 1480.11 ± 94.71 g. The highest value of gastrosomatic index (GSI) was in spring and the lowest was in winter. In other words, the greatest weight of fish stomachs was observed in March, spring, so the highest feeding intensity was in spring for this species in coastal waters of eastern Hormozgan province. Vacuity index (VI) was calculated 30.14 ± 5.72 for R. oligolinx which ranks this species as a relatively edacious species. Season based analysis of VI data revealed the lowest amount of VI or in the other words the highest number of full stomachs in spring. Index of food preference showed that fishes and shrimps constitute 54.09 and 37.72 percent of stomach contents, respectively and were the main prey and the second priority prey consumed by this species. Moreover, relative length of gut was 1.41± 0.02 indicating its carnivorous feeding regime. The present findings contributed to a better understanding of feeding habits of this less known and near to threatened species and helped to realize its position in the marine food web.

This study was aimed to estimate growth parameters and mortality rate of stickleback caught from the southern Caspian Sea. Fish sampling was conducted from February 2018 until June 2018. To do so, 247 fish were sampled, weighted and biometric assays were done, among which 237 samples were sex-determined. The numbers of male and female fish samples were 106 and 131, respectively. Kolmogrove-Smirnov test showed a significant difference in length-frequency distribution between sexes. Randomization test was applied to compare mean length of male and female samples which indicated a significant difference between sexes. Results indicated that the shortest and the longest fish recorded in the Caspian Sea were 1.55 and 6.93 cm, respectively. Vonbertalanfi Growth factors in the Caspian Sea was obtained (L∞= 8.797 cm, k=0.356 per year and t0= -0.699 year). Mean natural mortality for male, female and total were 1.86 year-1, 1.76 year-1, and 1.64 year-1, respectively. Mean relative weight of the female, male and total fish were 85.2%, 83.02% and 85.16%, respectively, implicating inadequate condition of the fish weight. The present findings help better understanding of biological status of stickleback stock in southeastern part of the Caspian Sea.