NEW TECHNOLOGIES IN AQUACULTURE DEVELOPMENT (JOURNAL OF FISHERIES)
Year:2008 | Volume:2 | Issue:2|Papers Count:9

Use of prebiotics, indigestible dietary ingredients that beneficially affect the host by selectively stimulating the growth of and/or activating the metabolism of health-promoting bacteria in the intestinal tract, is a novel concept in aquaculture. Three replicate groups of fish (initially averaging weight and biomass were 16.14±0.38 g and 821.58g, respectively in each group) were kept in 800L fiberglass tanks under homogenous condition and fed diets containing prebiotic inulin levels ranging from 1% to 3%. The basal diet was contained 3% cellulose. An 8-week feeding experiment was conducted to investigate the effect of different dietary prebiotic inulin on production and intestinal micro flora density of juvenile Beluga, Huso huso. The results of linear regression showed there was a negative relationship between production index and supplementation level of inulin. At the end of trial, the density of colony count, yeasts and moulds and lactobacillus count was decreased with supplementation level of inulin. The 1% inulin treatment showed an enhaced survival without any significance among treatments, and intestinal lactic acid bacteria (LAB) increased in this group in comparison with other groups. The experiment indicated that the prebiotic inulin didn’t influence the increase of the production and it is not appropriate for supplementation in the diet of beluga.

Zangi Creek is located in the Northwest of Persian Gulf, a branch of Moosa Creek. Zangi creek is important for aquatic animal’s diversity and richness. After establishing the Petrochemical special Economic Zone (PETZONE) in 1997 near the Zangi Creek, sludge and effluent was released in this sensitive ecosystem. A survey of the creek was performed, assessing macrobenthic density lead, cadmium heavy metals, total organic matter, and Grain size of sediments, pH, temperature and salinity in winter and summer 2006. Benthos abundance was assessed per square meter in laboratory after washing sediments with 500 micron standard sieve. Samples were transferred to laboratory in 4oC and analyzed by atomic absorption according to the related standards. It was found that minimum and maximum levels of Cadmium in water ranged from 0.07~0.12 ppm and in sediments ranged from 1.68~2.88 ppm, Lead levels in water ranged from 0.19~0.29 ppm and in sediments ranged from 1.43~7.31 ppm. Results showed that the distinct creek was more polluted than eastern part with high levels of Cd, Pb, pH and low levels of salinity. The physico-chemical changes such as pH and salinity were significantly correlated to metals in sediments (P<0.01). Although Macrobenthos density was very low at discharge area but density didn't have a significant correlation with metals (P<0.05).

At the caught period 765 of Barbus luteus at the Dalaki and 891 at the Helle Rivers were caught, so alimentary tract of fishes were investigated. Maximum and minimum of total length of fish was 350 and 45 mm respectively. Ratio of intestine length to total length (RLG) was 4 for one year old and 2.2 for 5 years old. Ephemeroptera was the most frequent in food item in the Dalaki River but Barbus luteus prefer Plecoptera and Odonata in both Dalaki and Helle rivers. Results showed that this fish has omnivores diet. Biodiversity of macrobentose in the Dalaki River was more than Helle River and in the spring and summer was more than the other times.

The aim of this study was to evaluate the Mercury (Hg) concentration in human scalp hair in Khoozestan Province according to gender and age category and its relation with fish consumption. Hair sample was completely related to methyl mercury (MeHg) exposure and can be used to estimate MeHg exposure in several months or a year before. Eighty-eight human scalp hair samples collected randomly. Also, the survey included a questionnaire designed to provide information about the parameters that influenced body Hg concentration. Determination of samples Hg concentration performed by LECO, AMA254, Advanced Mercury Analyzer according to ASTM Method D-6722. Overall mean concentration in the hair was 1601.05±232.68 ppb (Mean±S.E). Mean concentration in the females and males’ hair was 1555.01±279.08 and 1658.89±394.88 ppb, respectively. Significant positive correlation was between Hg concentration and number of fish meals (P<0.01). In 2.27 percent of samples (2 samples), mercury concentration was more than EPA & WHO threshold level (10ppm).

In this research the sampling was done from the organisms of piles of Imam Khomeini port in 4 stages, each Three months, from January 2005 to October 2006. Five stations were chosen and samples were taken from three zones: super tidal zone, inertial zone and sub tidal zone in 1×1m2. At the same time, the environmental factors (pH, Salinity, DO, Temperature) of each stage were measured. Ecological indices such as Shanon, species richness, Simpson and evenness were calculated. There results showed that the diversity of organisms in piles of Imam Khomeini port was low, but the species richness was high. Barnacle (Balanus amphytrit) was the dominant species in all 3 tidal zones. Results of variation analysis between diversity and environmental factors were significant only for temperature (-0.349). Temperature was the only factor which had significant effect on diversity of biofouling organisms; other factors (i.e. pH, DO and Salinity) had no significant effects. Moreover, the results showed that the increase in temperature causes decreases in biodiversity but it increases the richness. On the other hand, the results revealed a positive correlation between temperature and Simpson index (0.380) and negative correlation between temperature and Shanon, evenness and species richness indices. Also a negative correlation between Simpson with Shanon, evenness, and richness indices, was observed. In brief, the results indicated that increases so it shown that increases in species dominance was joint with decreasing in biodiversity and species richness.

Along aquaculture, ornamental fish culture has been shown a tremendous growth during these years. The huge attention toward dried food in ornamental fish culture is caused by the difficulty related to live-food preparation. The main objective of this study is to adapt fighter to the dried diet. Experiment was conducted in identical conical vessels with volume of 600 ml. Fish were fed by three diets including died artemia, live artemia and dried feed. The diets were assigned to conical vessels with 15 fish each, with two replicates for each diet. The result revealed that growth and survival rate improved (P<0.05) in fish fed by live or died artemia compared to fish fed by dried feed. Natural behavioral pattern was also affected by the type of the food. Feeding by dried feed reduced aggressive behavior compared to arteimia containing food. In conclusion, adaptation to dried feed caused a reduction in growth rate and also occurrence of stereotype behavior in fighter. This condition suggests that fighter hardly accepts dried food in the early life stage.

The study was conducted to determine suitable characters for separating brown trout (Salmo trutta fario) populations from Tajan River and Babolrud River in autumn 2006. Using electrofishing, one hundred two specimens were collected in two rivers (forty one from Shirinrud, thirty one from Ashekrud, thirty from Kelyareh). Twenty nine morphometric and seven meristic characters were analysed. Using PCA, the best separating characters of populations were determined. Among the morphometric characters, six factors accounted for about 79% of variation within individuals of the three populations including: head width, inter orbital length, predorsal length, pecto-ventral length, mandibular length, total length, head length, eye diameter, pectoral fin length, head depth, postdorsal length, post ventral length, caudal peduncle length, post anal Length, Adipose fin length. In the case of meristic characters, three factors accounted for 60% of variation within populations including: anal fin ray, gill rackers, dorsal fin ray. The results showed that meristic characters are more important than morphometric characters in serparation of populations.

Lake Choghakhor is a shallow ecologically and economically important water body in eastern part of Iran. During last decade Lake Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduction causing a serious problem in its trophic states. So in this study water quality for physical, trophic state indicators, total phosphate, algal chlorophyll, Secchi disk transparency, biomass of macrobenthose (seasonal) was studied monthly between May 2004 to April 2005. Now submerged plants especially Myriophyllum spicatum have covered almost the entire lake and dense macrophyte beds (Polygonom amphibium), located on the south east end of the lake appear to act as a sink for these nutrients. Lake Choghakhor appeared to be in a macrophyte dominated clear water state with low TP (annual mean: 24±15mg.l-1) and chlorophyll a (annual mean: 3±1.28 mg.l-1) and very high Secchi depth. Fish yeild potential was estimated according to TP model as 34.4 kg.ha-1, production value for macrobenthose was 4.7 mg DM m-2yr-1 and annual fish  production obtained by macrobenthose was about 282  to 376 kg.ha-1yr-1.