جستجوی مقالات مرتبط با کلیدواژه « پرورش ماهی در قفس » در نشریات گروه « شیلات »

This study was conducted to investigate the possible effects of cages culture Asian sea bass fish (Lates calcarifer) on the population structure of macrobenthos in the Rigo area of Qeshm Island in Hormozgan province during a breeding period in 1397 were investigated. The average abundance of macrobenthos at the location of the cages culture and the refrences site in this study was equal to (52765 ± 19154 in m2) and (50642 ± 21002 in m2), respectively.The results showed that at the time of the study among the identified the genus of Ammonia sp. With a relative abundance of 73.41 percent at the location of the cages compared to the control station and Archasterope sp., Spirolochulina sp. and Nephtys sp. with a relative abundance of 63.9%, 49.1% and 12.6%, respectively, were more dominant in the control station compared to the location of the cages.The loading rate of organic matter in the bed of the cages was significantly affected by fish farming activities and in some times showed a significant difference with the control station (P<0.05). In general, at the time of the study, activities related to fish farming in cages had no effect on the population structure of macrobenthos in the study area.

The establishment of aquaculture cages in the right place will be associated with the least adverse effects on the ecosystem, so the quality of sediment is very important in monitoring fish cages farming. The aim of this study was to investigate the sediments chemistry parameters around fish cage culture in the southern of Caspian Sea (Nowshahr region). Sampling was conducted in four stages of the breeding period during 2017 and 2018, underneath the cages and at 200m and 1000 m longitudinal distance in four geographical directions from the cages. Based on the results the variations in different forms of phosphorus such as Loosely-P, Fe-P, Al-P, Bioava.-P, Ca-P, TIP, Res.-P and TP were 1.2-13.8, 22-114, 12-121, 37-211, 61-2170, 150-2223, 0-937 and 203-2283 µg/g. dw, respectively. The order of different forms of phosphorous were registered as Ca-P>Res.-P >Fe-P>Al-P>Loosely-P. The variation range of pH, Eh and TOC% were 8.05-8.60, (-63)-(-83) and 1.36-7.87, respectively. The results revealed that temperature, Eh and pH had the main role in the adsorption and release of loosely-P, Fe-P and Al-P. Comparison of 25-75th percentiles of total organic carbon (1.97-2.60%) with permissible threshold showed that the sediments of Nowshahr region can be classified as moderately polluted.

This study was designed to determine the sediment structure, Total Organic Matter (TOM) and facultative anaerobic bacteria communities of sediment affected by cage culture of rainbow trout in the coastal waters of Abbas Abad area (southern basin of the Caspian Sea). For this purpose, sediment samples were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). Determination of sediment grading showed that its structure was composed of silt-clay (91.7%) and very fine sand (6.44%) and the sediment structure was not affected by the cage culture. The Total Organic Matter was significantly different only between the sampling periods (P<0.05) so that the highest amount of Total Organic Matter (TOM) was observed during the production period whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the factors studied in the vicinity of small scale fish cages due to the short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.

The aim of this project was to study the feasibility of cage fish farming based on the evaluation of physico-chemical parameters effective on water quality and the trophic status (scaled and unscaled) at various depths of water and different months in the southeast of the Caspian Sea (Goharbaran region). The total numbers of 154 samples were collected at eight stations from three depths (5, 10 and 15 m) during 12 months. Results showed that the amounts of water temperature, transparency, pH, dissolved oxygen, BOD5, total alkalinity and TSS ranged from 9.00 to 29.00˚C, 0.50 to 12.00 m, 8.05 to 8.74, 5.76 to 12.85, 21 to 195 and 0.00 to 0.12 mg/l, respectively. In addition, the values of NH4, NH3, NO2-, NO3- and PO4-3 ranged from 0.007 to 0.051, 0.001 to 0.010, 0.002 to 0.015, 0.043 to 0.477 and 0.014 to 0.077 mg/l, respectively. Scaled and unscaled trophic index were 3.42-5.52 and 2.61-5.85, respectively. Therefore, the proper temperatures for cultivation of salmonids species in this area were begun in October and ended in March. In the current study, results of pH and dissolved oxygen were consistent with the standard range of pH (7.80-8.50) and dissolved oxygen (>5 mg/l) for cage fish farming. Although, Goharbaran region were appropriate for cage fish farming in terms of nutrients, but this region was evaluated as mesotrophic (5.97±0.73) with high risk of eutrophication (>4).