JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2008 | Volume:6 | Issue:3-4|Papers Count:12

Changes in quality of silver carp minced meat (Hypophthalmichthys molitrix) containing cryoprotectant were investigated. Minced meat from fresh fish was mixed with cryoprotectant consisting of 4% sucrose, 4% sorbitol, 0.3% polyphosphate (a blend of tetra sodium pyrophosphate and sodium tripolyphosphate with ratio 1:1), then packed in ziploc bags and frozen at -35oC and stored at -18oC for 6 month. Changes in moisture content, crud protein, total lipid, peroxide value (PV), thiobarbituric acid (TBA) and free fatty acids (FFA) were investigated at months 0, 1, 2, 3, 4 and 6. PV and FFA increased during 6 month frozen storage at -18oC (P<0.05). TBA showed an increasing trend, after a decrease in the 2nd month until 6th month but its value was very far from standard spoilage. In addition, moisture content and total lipid of the mince did not change significantly during 6 month frozen storage. Frozon storage of the mince containing cryoprotectant did not significantly affect the crude protein in most of the tested storage periods (P>0.5).

Biosorption of cadmium, lead and nickel ions by Aspergillus niger fungus was investigated as a function of initial solution pH, initial metals concentration and biomass dosage in a ternary system. Experiments were performed to determine the removal of heavy metals from aqueous solution. The bioaccumulation of Pb(II), Cd(II) and Ni(II) by this fungus was characterized to evaluate its applicability for heavy metal removal. The range of condition initial solution pH, fungal biomass concentration and initial metal ions concentration for heavy metal removal were determined 1.3-8.7 pH, 0.01-0.75 g/l and 0.5-37.5 ppm, respectively. Experimental results indicated that the optimal of in these conditions were 5, 0.38g/l and 19 ppm. Respectively. Data from a batch study was showed that maximum biosorption capacity of the biomass for removal heavy metal ions was obtained as 94.47±2.13%, 79.81±1.15% and 99.73±2.58% for cadmium, Nickel and Lead, respectively. According to these observations biomass of A. niger is a suitable biosorbent for the removal of heavy metals from industrial wastewater.

The influence of starvation on cholesterol, glucose, and protein plasma levels and tissue gluconeogensis was assesed. After acclimation to the experimental conditions, two groups of 45 fish were assigned to two outdoor concrete tanks (4m×2.7m×1.5m). Before starting the experiment, fish were fed twice daily at the rate of 1.7 % body weight with the commercial diet. Upon starting the experiment, one group of fish was deprived of food and the second group continued receiving food on similar basis. Sampling was carried out at the beginning and 10 days intervals up to 60 days by taking five fish randomly from each group. Blood samples were obtained from tail vein, centrifuged to extract serum for measuring cholesterol, glucose, and protein spectrophotometrically. Results showed a decline in cholesterol level at early days and increased towards the end of the experiment, so that no significant differences between fed and unfed group was found. Significant differences was found between serum protein level of fed (4.50 mg/dl) and unfed (3.74 mg/dl) fish (p<0.05). Blood glucose levels declined significantly, reaching from 113.90 to 60.60 mg/dl in unfed fish (p<0.05), whereas in fed fish remained unchanged. The results also suggest that rainbow trout are well adapted for prolonged starvation and glycogen and lipid body reserves meets the metabolic requirements during feed deprivation. The effects of gluconeogensis on fat tissues and changes in blood cholesterol level are discussed.

Dorsal and ventral muscles of wild and farmed common carp (Cyprinus carpio) were analyzed for proximate and fatty acid composition. The proximate analysis revealed that total lipid content of dorsal and ventral fillet portions of wild and farmed common carp was 4.4%, 5% and 2.9%, 2.4%, respectively and the difference among them were not statistically significant (p>0.05). The moisture content ranged from 73.2% to 80.8%. The protein content ranged from 13.7% to 20.6% and crude ash from 0.82% to 0.96%. Among all the samples studied for saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) (whether farmed or wild), palmitic (C16:0), oleic (C18:1n-9) and linoleic (18:2n-6) acids were the predominant fatty acids, respectively. Dorsal portion of both fish contained a higher level of arachidonic acid (20:4n-6) than ventral portion (p<0.05). The results showed that fatty acid profile did not differ much between wild and farmed common carp and both fish contained a relatively good level of n-6 and n-3 polyunsaturated fatty acids (PUFA), particularly linoleic acid (C18:2n-6), docosahexaenoic acids (DHA), and eicosapentaenoic acids (EPA).

Beluga, Huso huso, fillet was prepared by the sous-vide method and stored at 2 and -18oC. Totally 55 packages of fillet were evaluated from physicochemical and quality aspects for a period of tweleve weeks. Organoleptic test as well as microbiological and biochemical examination were carried out for quality control of the processed samples. Microbiological tests included total bacterial load as well as psychrophilic bacterial counts such as Pseudomonas, Aeromonas and Serratia. Salt absorption percentage and pH values were measured. Salt absorption and pH were higher for fish samples processed with LTLT (Low temperature long time) method compared with those prepared by HTST (High temperature short time).The Aeromonas bacterial contamination was negative until the end of storage period. The total bacterial count and Pseudomonas bacterial contamination occurred in samples prepared, but Serratia bacterial count was only observed in sample prepared by HTST. The Pseudomonas bacteria and total bacterial count were higher for fish samples processed with HTST method compared with those prepared by LTLT. Statistically significant difference was observed in Pseudomonas counts in samples processed with HTST and LTLT preserved in 2 and -18oC (p<0.05).In sensory properties, the HTST prepared samples kept their high quality for a period of six weeks, whereas the LTLT prepared fishes were in good shape for a period of ten weeks in refrigeration. But the HTST and LTLT prepared samples kept their high quality till the end of freezing storage.

The population structure and fishery of kutum (Rutilus frisii kutum) in the Iranian coastal water of the Caspian Sea were investigated using a combination of size frequency and size- at- age data derived from regular monthly samples of commercial catches. Total catch of kutum (including poaching) was estimated 6612.5 tonnes that comprised 43.3 % of the total catch of all commercial bony fish species in 2004-2005 fishing season.Results showed that the mean fork length was 38.2±5.9 cm. The kutum ranged in age from 1 to 8 years with a mean age of 4.2 years. The age group of 3, 4 and 5 years constituted 85.5 % of the age composition. Parameter values of the Von Bertalanffy growth equation fit to size at age data (males and females combined) were: K=0.15 year-1, L¥=60.7 cm (fork length) and t0=-1.75 year. The annual instantaneous rate of total mortality (Z) derived from length converted catch curve was 0.88 year-1. The annual instantaneous natural mortlity (M) derived from Pauly’s imperical formula was estimated 0.31 year-1 and annual fishing mortality was 0.52 year-1. Overall results showed that the growth rate of Caspian kutum had decreased in comparison to previous years, which seems to be due to non selective artificial breeding in more than 20 years of practice.

Dreissena polymorpha and Anodonta cygnea of Bivalvia class are able to filter organic and inorganic materials through the water. Nowadays the filtrations rates of these organisms are studied as a tool for treatment and removing suspended and dissolved materials. So in this research, the affection of these two mussels on nitrate concentration is studied that indirectly reduces concentration of nitrate due to filtration tests and indirect absorption of nitrate from artificial wastewater. These tests were performed by method Jfrgensen (1990) in open and closed systems. This research is done in 3 different weights of mussels and was repeated 3-10 times in Science & Research University laboratory in 2006. Its result was studied in excel soft ware. In two species in open and closed systems the result showed that there is a positive correlation between the weight of shell masses and the filtration rate of nitrate and the filtration rate of Chlorella (R2=0.99). In D. polymorpha there is a negative correlation between concentration of nitrate at the wastewater entry on one side and the filtration rate of nitrate on the other side (R2=0.97) despite the fact that in A. cygnea there is a positive correlation between concentration of nitrate at the wastewater entry and the filtration rate of nitrate (R2=0.90). The result also showed that the absorption rate of nitrate in D. polymorpha is 0.001 - 0.004 mg.l-1 and in A. cygnea is 0.003- 1.4 mg.l-1.

The lethal concentration of the Sefidroud suspended sediment in a 4-days experiment (LC50 96h) on stellate sturgeon fingerling (Acipenser stellatus) of 3-5g weight was investigated in 2005. Totally five concentrations and one control all in triplicate were considered. The results showed that LC50 96h and LC50 24h of sediments on stellate sturgeon were 8538.86 mg/l and 74267.70 mg/l, respectively.

Stress indices and its relation to success or failure of maturation induction with GnRH in farmed brooders of stellate sturgeon, Acipenser stellatus, was investigated. For this purpose, 11 brooders of eight years old (5 females and 6 males) were injected with GnRH hormone (female with a total dose of 10mg/kg injected with 10% and 90% of the dose at 12 hrs interval, while males were injected once using a 15mg/kg dose). Blood samples from males (0 and 12hrs after injection) and females (0, 12 and 24 hrs after injection) were taken to analyse the blood and hormonal parameters.Results showed that ovulated brooders had higher cortisol, lymphocyte and eosinophile levels than nonovulated fish, while, nonovulated fish had higher neutrophile level. Cortisol, neutrophile, lymphocyte and eosinnophile levels did not significanty differ between spermiated and nonspermiated male brooders (p>0.05).