مجله علمی شیلات ایران
سال بیست و دوم شماره 1 (پیاپی 82، بهار 1392)

Soil is one of the most important natural resources and foundation of formation and development of human civilized societies. Sediments are also important at receiving organic matter, material budgets and distribution of benthic organisms. As part of the ecological study of Choghakhor Wetland where located in Chaharmahal-o-Bakhtyari Province, some physical and chemical characteristics of sediments in this wetland were studied in relation with benthos environment. Sampling was performed in 10 stations with 3 replicates in each station since April 2010 to March 2011. The results showed that wetland sediments texture at different stations was not differeny and sediments component showed no significant differences between the stations. But the components showed significant differences between the stages. There was no from spring to winter (timing change’s) amounts of organic matter increased and showed the significant differences between seasons. Also sediment’s moisture percent and organic matter in different seasons showed significant differences. There was no significant differences in the sediment texture between the season’s. The Pearson correlation coefficient showed positive correlation in the 0.01 level between percentage of organic matter and sediment moisture that indicating a high capacity for water storage in organic soils.

Silver carp (Hypophthalmichthys molitrix) minced (SCM), as ready-to-cook and high nutritious product, can successfully introduce to consumers and significantly dissolves current problems of limited demand for whole/fresh market. Short shelf-life is one of the most important barriers to developing industrial production of minced fish. Application of Hurdle technology with minimally processing to improve storage life of fresh seafood has become increasingly popular. The main objective of this study was to compare the effects of lowring temperature (3-5 oC), Modified Atmosphere Packaging (MAP) (condition 50:5:45 for N2:O2:CO2) and Green Tea Extract (GTE) (1000 ppm) with normal or Aerobic packaging (AP), on the chemical and sensory characteristics of SCM within refrigerated storage. Total polyphenolic compounds measured in GTE was 14.33±0.88 μg/ml. Results of Peroxide Value showed that all treatments can effectively protect SCM against oil oxidation, compared with AP, after 4 days. Using MAP and/or GTE treatments reduced the Free Fatty Acids (FFAs) formation ratio, because, in contrast with AP treatment, FFAs increased significantely (P<0.05), only after 16 days storage. Thiobarbitoric Acid Reactive Substances (TBARS) of AP samples in 16th days was 2.51±0.21 mg that was upper than accepted limits. Effects of GTE treatment on TBARS increasing was not significantly different compared with AP. pH trends were ascending and GTE and MAP treatments had no significant effects on pH increasing. According to sensory evaluation, MAP had higher total quality score compared with GTE treatment and showed no significant difference with MAP+TE during storage, suggested that MAP more effectively retards and/or inhibits microbial growth in refrigerated SCM.Combined treatment (MAP+GTE) was selected as an effective method that can extend the shelf-life of SCM up to 4 days at refrigerated storage.

In this present study, Cichlid Kaliko (Labeotropheous foellobroni) fallowing was exposed to 17-alpha-methyl testosterone at 2 stages of development including prior to maturity (larvae) and after puberty (broodstock). The influence of sex hormone on the larvae was also explored. The first group was the larvae under the four treatments (0, 50,100, 250) mg per kg of food and hormones that broodstock group also included four treatments (0, 100, 250, 400) mg per kg food three replicates were performed in a period of 30 days. Hormone was added to fish food. Results showed that treatments had a significant difference in fish growth, which correlated with increased amounts of 17 alpha-methyl testosterone. In group I, food with 250mg/kg testerone resulted in an increase in growth indices (i.e.s, SGR=1.4, ADG= 6.5) with a mortality rate of 48.3 percent. In group II results showed that treatment of G (400mg testosterone per kg food) produced larvae with maximum growth indices (SGR=0.91, ADG= 3.6) and the least mortality rate of 31 percent Research revealed that 17 alpha methyl testosterone could have an effect on Calico fish sex changes in both larval and stock stages.

Slender Mudskipper (Scartelaos tenuis) is one of the dominant fishes in inter-tidal mud flats area. Reproduction and population parameters of 2047 Slender mudskipper were studied monthly from october 2008 to september 2009. The asymptotic length (L∞) and growth coefficient (K) were estimated as 19.43(cm) and 0.64(yr-1), respectively. The minimum and maximum T.L. was 1.1 and 19.5cm, respectively. The value of to was -8.28, and Tmax was 4.6 year. The growth equation of Von Bertalanffy was obtained at L(t) = 19.43(1- exp (-0.64(t- (-0.28))) for this species. The rates of natural mortality (M) on Pauly's empirical equation, was estimated 1.51 (yr-1). Five cohorts were distinguished annualy on Bhattacharya's method with mean length of 7.89, 11.42, 13.86, 15.6 and 16.81cm. Maximum recruitment was in Seprember at 18.8 percent. Reproductive studies showed that peak of maturity season occurred in April. The female to male ratio was calculated as 1:1.47 and chi-square analysis showed that it was statistically significant deviated from 1:1. LM50 is attained at a total length of 13.3cm. The mean of absolute and relative fecundity were 6742 (±1939) and 707 (±210), respectively. The length-weight relationship was as W= 0.02735 L 2.1655, that was isometric growth. Result showed that slender mudskipper population was in congenial condition, nevertheless less not evaluated.

Fish sauce is a dark liquid which produced from fish fermentation in a very high salt condition. This product has a long history and is produce in different procedures and names throughout the world. In Iran, production of fish sauce consists of two steps. At first, fermented extract or Suru is produced from fresh or dried sardine and Suru is cured with addition of spices. This study was conducted for the first time in Iran for industrial production of fish sauce from dried Sardine. For this study, fresh sardine was provided from Bandar- Abbas fishery center. The fish were sun dried and used for fish sauce production. The effects of mechanical dicing, adding of salt in two levels (100 and 80 percent) and addition of citric acid at 2% were investigated. Sampling was achieved with separation of aqueous phase by vacuum and filter paper. Then, acidity, electrical conductivity, total nitrogen, trimethylamine and salt concentration were measured in the extracted liquid. Results showed that acidity, electrical conductivity and total nitrogen increased, however the salt content remained constant and the trimethylamine content was decreased during fermentation period. Increase in total nitrogen indicated an increase in protein hydrolysis and nutritional value of the product. Whereas, reduction in trimethylamine content showed a decrease in the number of spoilage bacteria during fermentation. The highest score in sensory evaluation of the products belonged to the low salt (80%) treatment.

Rainbow trout, Oncorhynchus mykiss is the most important cold water farmed fish in Iran. Several cultivated stocks have been imported to Iran and some fish farms have focuesd on the culture and breeding of these stocks all around the country. In this study, the genetic structure of Spanish and American stocks of rainbow trout was investigated using 4 pairs of microsatellite markers and 30 specimens of fish from each stock. Allele sizes at OMY77, OMY325, OMM1329 and OMM1332 loci were in the range of 102-178, 100-150, 122-198, 172-204 bps respectively. Average number of observed alleles in American and Spanish stocks was 11 and 11.5, respectively. Average number of effective alleles in Spanish and American stock was 8.65 and 8.03, respectively. The mean of observed heterozygosity for American and Spanish stocks were calculated as 0.59 and 0.63, respectively. The mean of expected heterozygosity for both stocks was very similar (around 0.86). The results showed a significant deviation from Hardy-Weinberg equilibrium at seven out of eight loci × stock. AMOVA test showed low (7%) genetic diversity between stocks, while the most (93%) genetic diversity was observed within stocks. Genetic identity and genetic distance between stocks were 0.831 and 0.186, respectively. Fixation index FST was calculated based on allelic frequency between two stocks was 0.012 with no significant difference between 2 stocks. The results of this study showed that while there was considerable genetic diversity within Spanish and American stocks, two stocks were very similar and showed very insignificant genetic differentiation based on 4 microsatellite studied loci.

The changes in chemical, microbial and quality sensory of fillets for silver carp fish treated with black cumin extract during refrigerated storage were investigated. The fish were divided into two groups. First group was dipped in black cumin extract with concentration of 1% and received the highest score in sensory evaluation. Then the fishes were wrapped in polyethylene package. The second group, as the control samples, were wrapped in polyethylene package after dipping in distilled water. All treatments were stored at refrigerator temperature (1±4°C). The microbial tests including total viable count, psychrotrophic count and chemical tests including peroxide index, thiobarbituric acid, free fatty acid value and total volatile basic nitrogen, with sensory evaluation, were done at 4°C over a period of 15 days. The results showed that the black cumin extract delayed lipid oxidation and protein analyses significantly in treated fishes. Psycrotrophic bacteria and total viable count of samples being treated with black cumin extract were maintained lower than the proposed acceptable limit (7 log cfu/g). In comparison to the control samples, microbial spoilage significantly decreased in treated samples. Furthermore, according to sensory analysis, the treatment with black cumin extract led to high quality during storage.The findings indicated that black cumin exerts had strong antioxidant and antibacterial impacts on silver carp fish, such that the shelf life of fillets being treated with black cumin were 2.5 times more than that of control samples during storage in refrigerator.

The effect of three different packaging methods including Modified Atmosphere Packaging (MAP), Vacuum Packaging and normal Packaging was investigated on the quality of Nile tilapia fresh fillets stored in the refrigerator's temperature. The packaged samples were examined for 10 days with regard to the changes in chemical (TVN, PV, pH), microbial (total viable count) and sensory evaluations. The results indicated that the samples packed in MAP condition had higher quality than that of other methods at the end of the storage period. In addition, the slower destructive impacts and microbial growth was observed in MAP. The results of present study suggest that packaging tilapia under MAP conditions results in the increase in the durability, storing, and distribution period for fillets.

A feeding trial with three protein levels (30, 35 and 40%) and three lipid levels (10, 12 and 14%) was conducted to evaluate the optimum protein and lipid ratio of Caspian Kutum (Rutilus frisii kutum). Six hundred and seventy five fish (1.15±0.01g mean ±SD) were randomly distributed in 27 aquaria (45L) and were fed four times daily for 8 weeks. Results showed that interaction between protein and lipid did not significantly affect the growth parameters. Weight increased with increasing dietary protein level up to 35%, and then decreased significantly. Specific growth rate (SGR) and average daily growth (ADG) of fish fed the diets containing 35 and 40% protein increased with increasing lipid level, but protein efficiency ratio (PER) of fish decreased with increasing dietary protein level. Fish fed the diet containing 40% protein and 10% lipid showed the lower protein productive value (PPV). Lipid efficiency ratio (LER) of fish fed the diets containing 30 and 35% protein decreased significantly with increasing lipid level (p< 0.05). Lipid production value (LPV) of fish fed the 35% protein and 10% lipid was higher than those of other treatments. Results regarding to the analysis of body compositions showed that dietary protein levels made no significant differences among treatments, but the increase of lipid level in diets led to fish body lipid increase and the highest amount of lipid were observed in fingerlings fed 35% protein and 14% lipid. Survival was 100% in all treatment. In conclusion, it appears that Caspian Kutum juveniles could adapt to 14% dietary lipid without negative effects on growth and the diet containing 35% protein with 14% lipid would be suitable for optimum growth of Caspian.

In May 2009, the fingerlings of Indian major carps, (i.e., catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus mirigala)) were conducted with mean weight 25.4±4.1g, 36.6±3.5g and 58.8±4.5g, respectively. Fingerlings of Indian major carps were cultured the fingerlings of chinese carps. According to the randomized complete block design with 4 treatments and 3 replications in earthen ponds. Four treatments were defined in species ratios and combinations.Treatment-1(T1) with 30 % of Indian major carps (catla, rohu and mrigal) and 70 % of Chinese carps phytophage (Hypophthalmic molitrix), big head (Hypophthalmichthys nobilis) and amur (Ctenopharyngodon idella)) with common carp, treatment-2 (T2) with 50% of Indian major carps and 50% of Chinese carps treatment-3 (T3) with 70% of Indian major carps and 30% of Chinese carps with common carp and treatment-4 (control treatment) with 100% of Chinese carps (with common density and combination in Khuzestan Province). Eevery 45 days, biometry was carried out by using the case net in earthen ponds. The culture period was for six month from May to November. The maximum net production of fishes was obtained inTreatment-2 (50% of Indian major carps) with mean harvest 4254.9 kg/ha. The experimental treatments were not significant with each other and control treatment. In end of culture, mean (SD) weight obtained for rohu, catla and mrigal were 1136±16, 726±122 and 773±89g in T1, were 1129±85, 902±78 and 788±125g in T2 and were 1054±38, 839±168g and 849±106g in T3, respectively. Statistical analysis showed no significantly different in total weight of fish harvest in treatments with control group (customary culture in Iran). However, this experiment determined that Indian major carp could increase production and diversity in warm water fish culture in Iran. *Corresponding author.

In this research for the first time tested antifungal activity of Ircinia mutans, collected from Kish Island in the Persian Gulf. The extracts were produced by Bligh & Dyer method, In vitro antifungal activity by Broth Dilution Methods against clinical pathogens Candida albicans ATCC10231 and Aspergillus fumigatus PTCC5009. The results conducted that the aqueous extracts didn’t have any antifungal activities on pathogens, minimum inhibitor concentrations (MIC) of the diethyletter extract was found on C. albicans and Aspergillus fumigatu, but MFC was not found. The MFC of summer and winter metanol extracts were 20mg/ml and 3mg/ml on A. fumigatus and 0.5 mg/ml and 1.5 mg/ml on C. albicans. Therefore secondary metabolites solutions in metanol, polar components have antifungal activity and it can be used for supplementary experiments to isolate and identify the fungicide active ingredient.

A total of 120 samples of adult common Kilka fish (Clupeonella cultriventris) were collected during spring and summer from the southern coasts of Caspian Sea (Bandar Anzali and Babolsar). Fifteen sets of microsatellite primers were developed from Clupeidae being tested on genomic DNA of common Kilka. Allele frequency, observed and expected heterozygosity, FST, RST, FIS index were determined. Five primer sets as polymorphic loci were used to analyze the genetic variation in adults of the common Kilka population. Results revealed that average alleles per locus was 13.1 (range 5 to 22 alleles per locus in regions, Ne=9.5). All sampled regions contained private alleles. Average observed and expected heterozygosity was 0.348 and 0.877, respectively. Deviations from Hardy- Weinberg equilibrium were observed in most cases. FST, RST and gene flow estimates in AMOVA and the genetic distance between populations indicated that the genetic difference among the studied populations was pronounced. The data generated in this study provide primary information on the genetic variation and differentiation in populations of Caspian common Kilka.

The present study compared the properties of Bighead carp (Aristichthys nobilis) visceral, viscera use of commercial enzymes (Alcalase, Papain, and Protamex), recovery protein and degree of hydrolysis in the various temperatures and times of hydrolysis process. According to results, increase in time and temperature in hydrolysis process, led to increase in both recovery protein and degree of hydrolysis. Maximum of these parameters were observed at 55°C and 60min. minimum of parameters were observed at 35°C and 15min. In addition, among enzymes being investigated, Alcalase had high rate of recovery protein and degree of hydrolysis in equal temperature and times different from others enzymes (Papain and Protamex). Maximum mean of recovery protein for Alcalase was %51.38±2.39 in 55°C and 60 min of hydrolysis process. Also, maximum degree of hydrolysis for Alcalaqse was more than 20% at 55°C and 60 min of hydrolysis process. In conclusion, use of Alcalase enzyme induces product protein hydrolysates from Bighead Carp (Aristichthys nobilis) viscera that have suitable quality than others enzymes (Papain, and Protamex).

The purpose of this study was investigation and comparison of physicochemical characteristics of produced fish sausage from minced fish meat and Surimi. Conventional method includes three washing steps were used to prepare Surimi. Chemical analysis of the products at time zero showed that Surimi sausage contained less protein, fat and ash due to the washing steps during Surimi preparation. Comparison of the colorimetric results of the products obtained from the Hunter lab color scale using image-processing toolbox of MATLAB program represented significant difference for “L” and “a” colorimetric parameters between the two types of sausages. To evaluate the textural property of the samples, puncture test was carried out. The results showed more firmness of the fish sausage compared to Surimi fish during storage period of 0, 14, 30, 45 and 60 days. The sensory evaluation showed that acceptability of the Surimi sausage was more than the fish sausage especially at 60 days of preservation. SDS-PAGE electrophoresis of the samples during the preservation times exhibited more intensity of the bands related to α-actinin, actin and β-trompomyosin in Surimi sausage compared to that for fish sausage. This study demonstrated that Surimi sausage has higher quality indicators than fish sausage.

The present study examined the effects of different levels of plant protein (soybean meal) on biochemical parameters heamolymph of freshwater crayfish (Astacus leptodactylus). For this purpose, the effects of different levels of soybean meal protein including 0%, 30%, 50%, 70%, and 100% diet on some biochemical parameters and ion heamolymph of freshwater crayfish were evaluated after 60 days of trial. Sampling of 75 samples crayfish with apparently healthy heamolymph was carried out at the end of the testing period. Based on the results, with increasing soybean meal in the diet, the amount of glucose, cholesterol, triglyceride, creatinin and total protein had a significant decrease compared to the control group. A significant difference was observed in the amount of serum enzymes activities between control group and the other treatments. The amount of Bun, calcium, and sodium were not significantly different between treatments. Also, the amount of K, Fe and P in the diets containing soybean meal had a significant decrease compared with the control group.