نشریه علوم و فنون شیلات
سال نهم شماره 2 (پیاپی 30، بهار 1399)

To identify the behavior of fish consumer in Iranchr('39')s largest fish market in order to improve sales and obtain customer satisfaction. After designing and completing the questionnaire, descriptive statistics and Friedman test, chi-square and stepwise regression were used for data analysis. Consumers were very much in agreement with the direct sale of Fish by producer in the market, government subsidies to buy fish, and the aquatic properties on the market. Their highest priority is to buy trout and then southern fish, shrimp, Caspian Sea fish and warm-water fish. More than half of consumers were introduced to the market for the first time through advertising and introducing their friends and acquaintances, and 46% were familiar with the market because of their home proximity. The most important marketing mix was advertising, and the most important reason for buying fish from this market was the freshness and diversity of the fish. Research shows that men buy more fish than women cross-country people, women born in coastal areas and high-income buyers. Given the tendency of consumer to be familiar with the market and the importance of advertising, paying attention to this and targeting male buyers will be very effective in market prosperity. Considering the numerous research results, including inserting aquatic properties and installing electronic signage on and off the aquarium in the market and helping improve household income is another way to improve customer satisfaction.

The present study was conducted in Electric Blue Cichlid Sciaenochromis fryeri in early larval developmental stages from the fifth day post hatching (DPH) until 51 DPH to determine day of transforming from embryo to juvenile. Morphological characteristics were evaluated by using ImageJ software. Allometric growth patterns were calculated based on the formula Y=aXb. Yolk sac depletion was occurred on day 9. Scales were developed on day 19 and finaly developed juvenile shape. allometric pattern of different body segments were calculated according to isometry, positive, and negative allometry. Positive allometry of head and tail prior to inflexion point and variation in allometric growth pattern in different body segment determine priorities of organogenesis for survival in fish early life history. The obtained results showed consistency between the larval morphological changes and development of organs related to sensory movements and larval behavior. Every morphological change in larvae displays the development and evolution of one of the organs involved in feeding, breathing, swimming and sensory organs.

The aim of the present study was to identify the phytoplankton species which producing domoic acid and okadaic acid toxins in coastal waters of Banar Abbas city, and to determine the concentration of domoic acid and okadaic acid toxins in water and shellfish samples.Water sampling was performed in winter 2015 and summer 2016 from coastal areas overlooking the discharge of municipal and industrial effluents. Shellfish were collected from the coasts of Bandar Abbas and Bandar-e- Lengeh. Phytoplankton toxins were measured by kit method and instrumental analysis based on ELIZA method.Pseudonitzschia delicatissima, Pseudo-nitzschia pungens and Pseudo-nitzschia seriata were identified in the production of domoic acid, while Dinophysis caudate and Prorocentrum Lima were recorded as okadaic acid producers in the coastal waters of Bandar Abbas. Water-soluble okadaic acid showed significantly higher concentrations than domoic acid. Instudied shellfish samples (Circenita callipyga, Barbatia candida, Telescopium telescopiumandThalessa savignyi), the measured concentrations of okadaic acid ranged from 59.8 ± 2.38 to 121.96 ± 28.25 μg / kg. This value for domoic acid was from 0.85 to 83.59 ± 38.72 μg / kg.Compared to the guideline values, the observed concentrations of okadaic acid and domoic acid toxins in the studied shellfish were lower than the allowable level.  But this value was recorded for the water-soluble domoic acid above the allowable value, which requires continuous monitoring to achieve the quantitative and qualitative pattern of phytoplankton toxins in order to support the safety of the marine ecosystem users in Hormozgan province.

The purpose of this study was to measure sensory, chemical, microbial, freshness and shelf life of packaged Tilapia fillets by vacuum and modified atmosphere methods compared to fillets packaged by aerobic method at refrigeration.

Treatments consisted of Tilapia fillets packaged by vacuum and modified atmosphere methods. The fillets packaged by aerobic method were as control samples.

TVB-N, PV, TBARS, total bacterial count, Staphylococcus and Pseudomonas bacteria, sensory parameters and freshness showed significant differences in experimental and control treatments (P<0.05). The studied factors did not show significant difference in modified atmosphere treatments compared to vacuum treatments (p> 0.05). Coliform, Escherichia coli and anaerobic bacteria were not observed in experimental and control treatments. Sensory evaluation and frshness were better in modified atmosphere treatment compared to vacuum treatment (p> 0.05). Chemical, microbial, sensory factors and freshness had significantly different in the experimental treatments compared to the control sample (p<0.05). The experimental and control treatments had good quality during 14 and 6 days at refrigeration.

Considering the absence of significant differences in microbial and chemical quality of experimental treatments and higher sensory evaluation and freshness of modified atmosphere treatment compared to other treatments, modified atmosphere packaging method is recommended for packing Tilapia fish fillet at refrigerator temperature.

The body chemical composition in aquatic organisms is related to nutrition, habitat, age and sex. On the other hand, knowing the amount of chemical compositions helps to select the appropriate species for human nutrition and food industry. In this study, the change in chemical composition of common carp in different weights was investigated. For this purpose, 25 two-year-old carp were studied during the second year of rearing from different weight groups from 500 g to 1600 g. Protein, fat, ash and dry matter content of fish meat were measured. The results showed that the mean protein content of carp was 10.209 ± 2.106 %, fat was 9.429 ± 0.937%, ash 1.407 ± 198 % and dry matter 21.13 ± 1.62%, respectively. In addition, the results of this study indicate that there is no significant difference between chemical compositions of carp in different weights (P> 0.05). The results of the present study show that there is no relationship between chemical compositions (protein, fat, ash, dry matter) and the weight of common carp and the weight of fish has no effect on the chemical compositions. Therefore, there is no difference in common carp meat chemical compositions in different weights.

Temperature is the main environmental factor affecting the development of fish eggs. In this study, the effect of incubation temperature on fertilization rate, hatching rate and growth in goldfish (Carassius auratus) was investigated. Egg and sperm production were obtained by ovaprim injection and artificial propagation. Eggs were incubated at four temperatures (21, 24, 27 and 30 °C) with 3 replicates for each treatment and cultured for 40 days at the same temperature. The larvae were grown in the same aquarium that had been hatched under the same temperature condition for 40 days. The results showed that there was no significant difference in fertilization rate of incubated eggs at different temperatures, but the highest (97%) and lowest (94%) fertilization rates were observed at 24 °C and 21 °C, respectively. The maximum incubation time was recorded at 21 °C and the minimum time required at 30 °C (P < 0.05). The highest percentage of hatching (74.4%) was observed at 24 °C and it decreased with increasing water temperature (P < 0.05). Although, the temperature of 30 °C showed the highest value of length, weight and specific growth rate of larvae in comparison to other temperature treatments, but the highest anomalies (13%) were observed in this treatment, too. The best temperature of incubation and growth of larvae is 24°C and 27°C for goldfish, respectively.

Astaxanthin is a precious material and has many favorites for human; it is extracted from some creatures such as Haematococcus lacustris. Researchers try to maximize the production of this material. In this research effects of linoleic acid (LA), TiO2 and SiO2 Nanoparticles (NPs) were investigated on astaxanthin production, and expression of two astaxanthin metabolic pathway genes (CRTO and CRTR). The microalgae was cultured in BBM medium for 19 days autographically. In 3rd day, treatments were added to the cultures and astaxanthin measured in 3 days respectively in logarithmic and stationary phases, also RNA was extracted, Real-time PCR applied and Gene expression investigated in 11th. 30 µM LA and TiO2 NPs (40 mg L-1) induced 3.4 and 1.5 times astaxanthin production compared to the control, furthermore, CRTO and CRTR under 30 µM LA and SiO2 NPs (40 mg L-1) treatments displayed the highest gene expression. It was demonstrated that special concentration of Linoleic acid and TiO2 NPs, as inducers, could be used for astaxanthin production; also, Linoleic acid has a direct relationship with astaxanthin production and CRTO´s gene expression in the microalgae.