JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2014 | Volume:2 | Issue:4|Papers Count:6

A 9-week feeding trial was conducted to determine the effect of dietary vitamin E levels (0, 100, 200 and 1000 mg kg diet) on the growth performance and hematological indices in rainbow trout (Oncorhynchus mykiss) fingerlings (initial weight of 2.1 ± 0.1). Results indicated significant effect (p<0.05) of vitamin E levels on the fish growth performance. In terms of hematological indicators, vitamin E levels significantly affected the hematocrit, hemoglobin, red blood cell (RBC) count, monocyte and eosinophil in rainbow trout. However, it did not change MCHC, lymphocyte and MCH values.

Processing efficiency of rainbow trout, amounts of by-products and their nutritional value as well as some correlations between whole fish weight and products yield were evaluated. Results showed that efficiency decreased up to 87.56 ± 3.43% for gutted fish and it reached up to 56.69 ±3.26% and 45.36 ± 2.37% for skined on and skinless fillets, respectively. The highest amounts of by-product were related to head and viscera which were 15.52 ± 2.00% and 12.62 ± 2.61% of body weight, respectively. A significant negative correlation was found between fish weight and head weight percentage (P<0.01). Also, the yield of headed and gutted product increased significantly by increase in fish weight (P<0.01). Among by-products, viscera and head were the richest sources of fat (17.4 and 13.0% of wet weight) and skin contained the highest amount of protein (24.1% of wet weight). Moreover, a significant presence of the most important and health benficial omega -3 fatty acids was detected in both head and viscera. Viscera and bone were also found as rich source of iron mineral.

Identification of intertidal echinoderms and the effect of environmental factors on their density and distribution in five stations around the Khark Island were seasonally investigated. Three transects were designated to cover the supralittoral, eulittoral and sublittoral zones within each station. The environmental factors such as temperature, salinity and total organic maters (TOM) were also recorded. Maximum and minimum water temperature were recorded in summer (35.94 ± 0.28) and in winter (18.34 ± 0.39) and the maximum and minimum salinity were recorded in winter (44.6 ± 0.14) and spring (37 ± 0.18), respectively. Maximum and minimum percentages of total organic maters (TOM) were observed in summer (9.63 ±0.71) and winter (3.39±0.15), respectively. Totally four species belonging to for families were identified, viz. Asterina burtoni, Echinometra mathaei, Holothuria atra, Ophiothrix sarignyi, the highest frequency of which was encountered by E. mathaei. The maximum density and distribution were found in spring and minimum in summer and winter.

Oxygen concentration the environment and cellular organisms is one of the effective factors during normal development of organisms. In the present study, the transcription levels of the hypoxia-inducible factors (hif-1, hif-2) were evaluated during development of an ancient fish species Acipenser persicus, in the normal oxygen density of environment. The transcription ofhif-1, hif-2 detected in all developmental time-points defined, from embryo to juvenile stages. Target genes transcriptions were normalized usingRPL6 as reference gene. Changes in normalized hif-1, hif-2 mRNA expression were statistically significant throughout developmental points (p<0.05). Our data revealed that the mRNA expression of hifswere low during embryonic development and then upregulated significantly at hatching and early larval time-points. Then, in the late larval development and juvenile stage the expression of hifs started to decline. The comparison between hif-1 and hif-2 mRNA transcription showed that maximum gene expressions of hif-1 and hif-2 occurred in 15 and 20 days after hatching, respectively. The increased expression of hifs suggests their association with two important events in the larval evolution, viz. internal feeding (yolk absorption) and external feeding. Also, the observed increase in mRNA expression of hifs during larval development of A. persicus can be attributed to increase in oxygen demand.

The effects of valerian, Valerian officinalis, and clove, Eugenia caryophylla, extracts as anesthetic chemicals were investigated on Panga siussutchi (12.95±0.92 mm, 16.85 ± 3.52 g). The fish were divided in 6 groups, each including 5 individuals and exposed to various concentrations (2, 3 and 4 g/lit) of clove and/or valerian extract. The mean time to induce sedition, the mean time to return and the mean number of opercular gill pulses to sedate and recover were measured. For both groups, the mean time to sedation was decreased by increasing the dose of the extract. In general, the mean time to onset of anesthesia for clove group was significantly lower than valerian. The mean number of opercular gill pulses during the sedation time was not significantly changed between different dose of clove, while it declined significantly by elevating the valerian doses (p<0.05). There was no mortality in both groups.Although V. officinalis extract could cause sedation in the fish, it needed relatively longer time to affect than clove, so it may not be a useful compound for sedation in P. siussutchi.

Age structure, growth and mortality index of 661 specimens of spirlin, Alburnoides eichwaldii, from Shirood River in Mazandaran Province were studied during April 2011 to March 2012. The average total length, weight and age of the specimens were 68.33 ± 16.92 mm, 4.9 ± 3.2 g and 1.32 ± 0.86 years, respectively. The fish were in the age range of 0+to 3+, of which the 0+year specimens dominanted the age groups in the river. The largest specimen was 111.4 mm in length and a weight of 15.5 g. Comparing total length and weight of fish showed significant differences various ages (P<0.05). Based on Pauly formula, population growth pattern was negatively allometric (b=2.94). Based on von Bertalanffy growth equation using the FiSAT program, L, K and t0 were 12.08, 0.55, and -0.47, respectively. The growth performance index was up to 3.65. Mortality indices for the fish were calculated as 2.41, 1.19 and 1.22, respectively for the total (Z), natural (M) and fishing (F). Considering the ecological, biological and ornamental value of spirlin as well as its vulnerabilty to serious environmental degradation, such studies may be useful in the protection of the species.