جستجوی مقالات مرتبط با کلیدواژه « Oman Sea » در نشریات گروه « شیلات »

In the present study, the exploitation status of Babylon snail was evaluated by sampling four fishing areas of this species in the north of the Oman Sea (Iran) including Pasabandar, Bris, Pozm and Konarak from September 2021 to September 2022. In order to estimate the amount of catch per month, sampling was done by collecting statistics and information from the landing site, by counting at the place and sampling at the time. The amount of Babylon snail fishing effort and catch indicates that Bris and Pozm stations had the highest and lowest catch rate as well as fishing effort (day-boat) at the time of snail harvest (P < 0.05). The average catch per fishing effort post Monson and per Monson time were 183 ± 79 kg and 117 ± 25 kg, respectively (P < 0.05). In general, the fishing status of Babylon snail species has a fishing effort of 4569 days - boat fishing per year and the average catch per fishing effort (CPUE) of each boat is about 150 kg and the average catch per cage is about 0.59 kg. According to the calculations, the average of virgin biomass was obtained 971 (918-1047) tons, the average of maximum sustainable yield (MSY) less than 250 tons and maximum constant yield (MCY) less than 180 tons and total allowable catch (TAC) less from 220 tons, respectively. The amount of Babylon snails catches on the northern waters of the Oman Sea (Sistan and Baluchestan province) is more than 670 tons per year, that its seems to be higher than the optimal catch.

Given the importance of Pampus argenteus (Euphrasen, 1788), and the overfishing pressure, this study aimed to determine some population parameters of this species (mortality and growth parameter) in the Persian Gulf and Oman Sea. Sampling was carried out using trawl, gillnet, and Moshta during 12 months from April 2018 until March 2019. In this study, 955 biometric samples were weighed. An information-theoretic, multi-model inference (MMI) approach was taken to analyzing grow and best model was selected using Akaike’s information criteria (AIC). Chen & Watanabe Method was used to estimate the natural mortality. Mean length and weight values (mean ± standard error) for males were 16.68±0.22 cm and 202.71±7.75 gr, respectively and for females were 20.57±0.34 cm and 350.12±15.95 gr, respectively. Results showed that the Gompertz was the best model for male and female. The logistic model can be used to explain growth of males (considering to Akaike difference was less than two). The value of asymptotic length, k and L0 in Gompertz Model were estimated 29.53 cm, 0.527 year-1 and 4.1 cm for males, respectively and 36.2cm, 0.448 year-1 and 4.1 cm for females, respectively. Natural mortality, fishing mortality and total mortality and E was calculated 0.7, 0.81, 1.51 and 0.54, respectively. Results of this study shows that this specie is under overfishing pressure and need to better management policies in this area including time, place and fishing gear limitation for catching. Also overfishing can be reduced with building Marine Protected Area.

In this study, a comprehensive assessment of the occurrence and spatial distribution of heavy metals including Nickel, Lead, Zinc, Copper, Cadmium and Chromium, as well as, TPHs in the surface sediments of the coastal areas and far from the coast of the Persian Gulf in Bushehr and Khuzestan provinces were performed to identify the possible sources of sediment contamination and determining the degree of pollution. Eight pollution indices were used to evaluate the quality of sediments in terms of heavy metal and TPH pollution. The investigated areas could be distinguished by a significant degree of heavy metal pollution of Nickel, Cadmium and Zinc. High concentrations of Nickel and Zinc were observed in stations around Nakhiloo, Bushehr. The comparison of average pollution indices between regions showed that both Bushehr and Khuzestan provinces, respectively, with the average of contamination degree (CD) (20.25 and 22.11), modified contamination degree (MCD) (3.38 and 3.69), pollution load index (PLI) (31.17 and 57.57), potential ecological risk index (PERI) (353.54 and 349.39) have a significant degree and risk of Nickel and Cadmium pollution, especially in Nakhiloo area, Bushehr. Investigating the spatial fluctuations of the concentration of TPHs in two provinces showed an increasing trend from Bushehr to Khuzestan. However, areas were located in no pollution or low pollution zonation and were safe from the adverse biological effects of TPHs. Comprehensive and impressive strategies to control and reduce these pollutions, especially in polluted areas, should be considered, so that the sources of these pollutions be managed.

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.

In this study, sampling of commercial vessels of Afsoon 1 was carried out in July 2020, at a distance of more than 10 miles in longitude24 50 to 24 60 and latitude 61 03 to 61 05. At the time of the study, trawl fishing was done 13 times at different times, 8 times during the day and 5 times at night. The total catch during the study period was 12306 kg and 8720 kg were caught during the day (about 71%) and 3586 kg at night (about 29%). The average catch per fishing effort (catch per hour) of the target species was 201 kg (67%) during the day and 63 kg (33%) at night, and the average catch per fishing effort (catch per hour) discard species were 71 kg (28%) during the day and 100 kg (59%) at night (P <0.05). The mean catch per fishing effort (catch per hour) of bycatch fishing species at 18 kg during the day and 9 kg at night were not significantly different from each other (P> 0.05). The Trichiurus lepturus species (64%) had the highest catch of target species, Epinephelus coioides species (53%) had the highest catch of bycatch fishing species and Ray fish (88%) had the highest catch of discard species. The Siganidae and Megalaspis cordyla species, appear to be active during the day and pipe fish, Anguiliformes and Belonidae species of night active.

Trichiurus lepturus is one of the most important and commericial species in the Persian Gulf and Oman Sea.In order to come up with the responsible fishing pattern,there was a need to identify  reproduction characteristics. Data were collected randomly from April 2019 to February 2020 from six major artisanal fish-landing sites in Hormuzgan Province (Bandar Parsian, Bandar Kong, Qeshm Island, Bandar Abbas, Bandar Sirik and Bandar Jask). In the detection of sexual stages, the 5-stage key of sexual maturity was used at the macroscopic level. In determining the spawning season, the gonado-somatic index(GSI) was used and its comparison in different months. The lowest GSI of female fish was in September (1.2). The highest GSI of male fish was determined in December with a value of 3.1 and after that in May 2.6. Examination of the GSI and reproductive stages showed two main spawning periods in the middle of spring and late autumn. Different sexual stages were seen in all months of the year, which indicated the batch spawning strategy in T. lepturus. During different months, significant differences in the sex ratio were observed, but during the investigation and in total, no significant difference was observed between the female: male sex ratio in the expected ratio of 1:1.The length at first maturity obtained 78.7 cm total length. It is necessary to ban fishing during the spawning season in order to protect the stocks of this species.

The purpose of this study to develop a framework for investigating the catch trend and estimation of optimized catch limit of the P. homarus stock by collecting catch data in the northern waters of the Oman Sea. In this research, the landing catch data of the northern waters of the Oman Sea (Sistan and Baluchistan province) for more than twenty years (based on tons) have been collected from the Iranian Fisheries Organization (1997-2019). The average catch for this study period is 33±6 tons with a 95% confidence interval of 27-39 tons, and the amount of catch increased during the study period (R = 0.37). The average (95% confidence interval) for the intrinsic growth rate (r), maximum sustainable yield (MSY), biomass of maximum sustainable yield (BMSY), and carrying capacity (K) were obtained 0.56 (0.4-0.78) annually, 140 (120 – 170) tons, 156 (95 - 255) tons, 313 (192-510) per year, respectively. Based on the trends of B/BMSY and F/FMSY ratios, it can be said that the increase in fishing mortality and the decrease in available biomass started in 2014 and continues. This research shows that the annual harvest of this species has reached its maximum amount and measures should be taken to reduce the amount of catch and fishing effort.

The Persian Gulf and the Oman Sea contain a variety of aquatic species. Among which, Parastromateus niger (Bloch, 1795), Black pomfret fishes are very important and, one of the tuna fish that has increased its catch in recent years. In this research during April to March 2020, trend catch and demographic characteristics and demographic characteristics of Black pomfret were estimated by collecting information from 4 catchment areas in the southern waters of Oman Sea (Sistan and Baluchestan) including Pozem, Konark, Beries and Pasabandar. In this study, more than 14,000 fish at the research stations were biometric and the growth parameters were infinite length of L∞ = 54 cm, growth factor K = 0.36 (yr-1), natural mortality M= 0.52 (yr-1), mortality and mortality (yr-1), F = 1.27, total mortality (yr-1), Z = 1.79 and exploitation coefficient (yr-1), E = 0.71, and the time zero was -0.39 for the years. This study shows that the annual harvest of Black pomfret stock has reached its maximum and any increase in fishing effort will affect this stock and will reduce the amount of exploitation in the long run.

Awareness of the amount of aquatic stocks in each water source is one of the first and most basic information needed to manage of fishery stocks. The Babylon snail species has commercial and export value and its catch has increased in recent years and has not been studied yet. In the present study, the exploitation status of Babylon snail was evaluated by sampling four fishing areas of this species in the north of the Oman Sea (Iran) including Pasabandar, Bris, Pozm and Konarak from September 2021 to September 2022. Biometric analysis was performed on a total of 2779 Babylonian snail specimens. The mean length (standard deviation) and weight (standard deviation) of total snails were 34 ± 5 in the range of 19 - 64 mm and 12 ± 5 in the range of 2- 66 g, respectively. Growth and mortality indices include infinite length (mm) L∞ = 71, growth coefficient K = 0.35 (yr-1), natural mortality M = 0.5 (yr-1), fishing mortality F = 1.75 (yr-1); Total mortality was calculated Z = 2.25 ± 0.29 and exploitation coefficient E = 0.78. Babylon snails have a recruitment in all months of the year and have two major recruitment peaks during the year. The Production per biomass (P/B) 2.15 ± 0.23 in the range of 2.38 - 1.92 and the average annual production is 12 ± 3 per year in the range of 9 - 15. The present study showed that the exploitation coefficient of this species was not desirable and it should be in order to maintain and sustain fishing of this species, appropriate measures should be considered, including reduction of exploitation.

In this study, the relationship between water physicochemical parameters (sampling of water and soil) and Babylon snail biomass was done by sampling from four fishing grounds of this species in the north of the Oman Sea including Pasabandar, Breis, Pozm, and Konarak from September 2021 to September 2022 by circular cages. The average values of different physicochemical parameters (pH, salinity, turbidity, TOM, dissolved oxygen, and sand and silt) and different nutrients (nitrate, phosphate, ammonia, and nitrite) in the before and after seasons (monsoon) did not show a significant difference (p>0.05) through one-way variance analysis (between several periods) comparison of averages. Temperature and silt parameters from different seasons (before and after monsoon) had significant differences (p<0.05). Multi-layer artificial neural network was used for the correlation among the snail biomass, physicochemical parameters, and water nutrients and it showed that Temperatures and Nitrite were the most impact parameters on (snail biomass). From September to November, the highest catch rate was observed and it was the main season of Babylon snail fishing in Sistan and Baluchistan region due to the decrease in the water temperature and increase in the nitrite content. This study can be considered for fishing sustainability, basic management in exploitation, and a better understanding of the biological and demographic characteristics of this snail species.

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.

Most fishermen use traditional methods to identify areas with fishing potential. Increasing demand for fish and the need to exploit marine resources in a cost-effective manner and reduce human activities have made the introduction and application of new methods important considerations. The use of remote sensing in fishing leads to successful fishing and reduces the cost of fishing and human activities. In this research, we have tried to identify the distribution of Yellowfin tuna in the Oman Sea using Remotely Sensed system and draw a map of their possible presence. For this purpose, the distribution patterns of tuna fishes were studied through catch data and monthly remotely sensed data (sea surface temperature, chlorophyll-a, sea surface heights, salinity and wind speed) for the years 2016 and 2017 in the Oman Sea using GIS and multi-criteria evaluation. The results showed use of remotely sensed data to determine the spatial and temporal distribution patterns of Yellowfin tuna is more than 70% accurate. By studying, the output of the catch distribution map and the test data was determined the proposed model is of optimal power for identifying Yellowfin tuna. On this basis, it can be mentioned that remotely sensed data could show potential fishing zone with a least error. Therefore, in future studies, the use of remotely sensed data for location of fishing and fishermen guidance is suggested, Also the results of this research could help fishery managers to ecosystem fisheries based on management and reducing the fishing effort for fish finding.

Longtail tuna (Thunnus tonggol) is an important commercial species. This species is often caught in the Oman Sea by gill net. This study was conducted to study the selectivity of longtail tuna gill net based on the length-body girth relationship from January to July 2019 monthly in Bryce, Ramin, and Konarak sampling areas. For this purpose, the caught fish were collected and the data of Longtail tuna was measured from the eye, pre-operculum, operculum, and maximum body height at each stage of sampling. Then, the net selection curve and the optimal length of the longtail tuna were calculated by the gill net selectivity model based on the net mesh size. From the results, the maximum fish length was estimated at 40, 50, 56, 65, 68, and 80 cm for the net mesh sizes of 10.1, 11.4, 13.2, 14.6, 15.2 and 17.8 cm, respectively. According to Lm50 of longtail tuna at 73.3 cm fork length, the fish caught with mesh size of 17.8 cm has a fork length greater than the average sexual maturity length of the fish. Therefore, taking into account the catch of the target species, T. tonggol, the results showed that mesh size of 10.1, 11.4, 13.2, 14.6, 15.2 cm are not suitable for catching T. tonggol in the Oman Sea. The use of 17.8 cm mesh size with the purpose of catching adult T. tonggol would be suggested for sustainable and responsible fishing for this species.