جستجوی مقالات مرتبط با کلیدواژه « بهره وری » در نشریات گروه « شیلات »

Nowadays, sea foods are considered to provide more than 50% of the nutritional demands of ‎human communities. Therefore, with the development of the seafood market, the aquaculture ‎industry continues to grow day by day. Currently, some aquaculture food ingredients are made ‎from low price fishes (in the form of fish powder) and plants. But, the production of fish powder ‎cannot be increased due to disruption of the stability of aquatic ecosystems; Therefore, alternative ‎and environmentally friendly sources should be developed for aquaculture food ingredients. ‎Microalgae biomass suggests as a natural source instead of fish powder because the cellular ‎metabolites of these microorganisms contain a combination of essential amino acids, unsaturated ‎fatty acids, vitamins, and pigments. In addition to these unique properties and bioactive compounds ‎that are a major component of aquatic nutrition, microalgae can increase the survival of farmed ‎species, and improve the color and quality of fillets. Microalgae have the highest biomass productivity ‎among photosynthetic organisms, including forage crops, and therefore have high commercial ‎potential. Also, the production of microalgae does not require special arable land and freshwater ‎resources, which makes the feed based on microalgae contribute to environmental sustainability. ‎This article is a review of studies on the potential and application of microalgae in aquatic nutrition ‎to increase the productivity of aquaculture products.‎

In order to do an economic study and measure the productivity of the factors of production of the coldwater fish in Kermanshah province, all of the active farms of this province in 2015 agricultural year have been chosen as the statistical population. A part of the required data for this study is taken from the published official statics, and another part is collected through interviews via questionnaires with fish farmers and the experts of the fishery department of Kermanshah. Then using Eviews software and with the ordinary least square (OLS) method, the production functions have been estimated; and through the priority model test, Cobb-Douglas production function was finally chosen. Results show that the variables of the geographic location, education, the number of the released juvenile fish, the number of juvenile fish losses and using the aeration devices have a significant effect on the amount of the production (p<0.05). The sum of the coefficients of independent variables in the estimated production function is around 0.08, which indicates decreasing (downward) returns to scale. The production elasticity of aeration devices and water-returning pumps is more than the other inputs, suggesting that this input should be used more appropriately for this economic activity. Also the coefficient of the number of juvenile fish is 0.69, which indicates that if the number of juvenile fish is increased one percent, the production of fish will increase by 0.69 percent; and the demand for more released fish shows the direction toward the optimal production.In this study, results have indicated that the experience of the farm manager has no significant impact on the production (p>0.05), but education has a significant and positive effect (p<0.05). Expressing that technological level in this activity is high. Since this industry is a new activity in this non-coastal province, Kermanshah, so it seems logical that the educational level of employers would have a significant effect on the production.The comparision of the production function and the lnTFP functions indicates that some of the factors of production, which had a significant effect on the production function, have no significant effect on the productivity, and vice versa. Hence, this leads us to the point that to achieve a greater profitability and an optimal utilization of the factors of production, the estimation of the production function is necessary, but not sufficient; rather for a more accurate assessment of using the factors of production, in addition to estimating the production function, calculating the productivity indexes and estimating TFP function is demanded, so that a more complete study is provided.

Fishing companies play significant role in value-added generation in Bushehr province. According to the current conditions and based on natural potentials, fisheries are the main sector in economic development of the Bushehr province. The purpose of this paper is to identify, analyze and rank factors affecting productivity of Bushehr fishing companies using group analytical hierarchy process (GAHP) technique. We applied two standard questionnaires which were filled with 100 fishermen and 18 fishery experts. The first group of questionnaires was used to assess the two main factors: Internal and external and five subfactors including: Governmental, structural, natural, soft and hard ware aspects. The second group was used to rank the same indentified factors in the first group of questionnaires. Results indicated that fishery headquarter of the governmental sub-factor, economic changes of the structural sub-factor, management approaches of the software sub-factor and the catch tonnage and its composition of the hardware sub-factor are the main parameters affecting productivity. Suggestions were made to improve productivity of the fishing companies in Bushehr province.

This study was conducted in vitro to assess lethality, LC50 and the possibility of bioaccumulation of cadmium in various life stages of Artemia urmiana. Artemia is highly used in aquaculture hence the response of the organisms to pollutants, such as cadmium regarding the increase in environmental pollution is of high importance. This experiment was performed in Faculty of Marine science and Technology, Islamic Azad University and Atomic Energy Organization of Iran in 2009. In the first stage, smaller than 1day naupliis were exposed to 10 different concentrations from 0 to 250mg/l Cd. LC50 of Cd in 24h of A. urmiana exposure was 189.33mg/L. Next, the accumulations of Cd in 5, 10, 15 and 20mg/l Cd were examined in 1, 5, 11 and 17 days of Artemia urmiana life. The results showed that Artemia urmiana has the ability of accumulation of cadmium and the accumulation level depends upon the concentration of the cadmium in the environment as well as different living periods of Artemia. We found that increasing the concentration of cadmium in the environment increases its accumulation in Artemia. There was a significant difference in accumulation of Cd between 5mg/l Cd (0.267ppm) and 20mg/l Cd (0.364ppm) in the first day of A. urmiana life (P<0.05). In all treatments of the 11 day Artemia, bioaccumulations of Cd increased with increasing of cadmium concentration. Maximum accumulation of Cd was in 20mg/l Cd in the 11 day Artemia. Results showed that although A.urmiana is resistant to Cd, however in 250mg/l, cadmium has significant toxic effects on Artemia survival (3.33%).

Cultured fish are presented in various sizes and prices in market. The present study aimed to investigate the proportion of nutritional value and price of various weight groups of bighead (Hypophthalmichthys nobilis) and to offer two indices for comparing nutritional value in proportion with fish prices. For this purpose, bighead specimens were prepared in market sizes and their dry matter, lipid, protein and ash content and fillet yield were determined. Then, the proportion of nutritional and financial value (NP) and justified price difference based on dry matter content (PDdm) were calculated for each weight group. The results showed that the light weight group has a higher NP index for dry matter, protein, ash and energy than medium and heavy weight group. The NP index was the same between medium and heavy groups. While the price difference between light weight and two other weight groups is more than calculated PDdm index, the light weight group is a proper choice for purchase.