JOURNAL OF AQUATIC SCIENCES
Year:2010 | Volume:1 | Issue:1|Papers Count:7

In this study chemical, microbiological and organoleptic evaluation of gutted and headed rainbow trout (Oncorhynchus mykiss) in two gas mixtures of modified atmosphere packaging (MAP) were conducted. Quality assessment of rainbow trout's stored in MAP (10% 2: 50%CO2: 40%N2 and 20%O2: 40%CO2: 40%N2) for up to two weeks at 4oC was conducted by the monitoring of sensory quality, total viable counts (TVC), total volatile nitrogen (TVN) and peroxide value (PV). Bacteria grew most quickly in rainbow trout stored in air, followed by those in MAP with formula 2 and the lowest counts were with MAP with formula 1. The formation of TVN increased during the time of storage. The highest content of TVN was obtained from rainbow trout stored in air, followed by rainbow trout stored in MAP with formula 2 and the lowest in MAP with formula 1.The formation of peroxide value increased during the time of storage. The highest value of PV was obtained from rainbow trout stored in air, followed by rainbow trout stored in MAP with formula 2 and the lowest in MAP with formula 1.Control samples were in moderate Organoleptic conditions and modified atmosphere packaged samples were in good Organoleptic conditions.

This study aimed to show the difference in cortisol concentrations and growth indexes with different starvation and feeding period consequents according to the IGF-I hormone level in blood with 4 treatments in 3 replications. Other indexes like Food Coefficient Ratio (FCR), Specific Growth Rate (SGR) and daily food intake were also examined during the experiment. Fish were fed twice a day ad libitum as follow during the 65 days: Treatment A (TA): Control treatment; Continious feeding, Treatment B (TB): 4 weeks starvation and 5 weeks refeeding, Treatment C (TC): 3 weeks of starvation and 5 weeks of refeeding, Treatment D (TD): 2 weeks of starvation and 5 weeks of refeeding. Each tank was containing 23 fishes in each unit with an initial mean weight (SD) 47.19±0.42. Blood were sampled for cortisol concentration measurment at the beginning of the experiment and at the end of the starvation and every 12 days in refeeding periods. There were no significant difference between the treatments in FCR (P<0.05). TB and TC had significant difference (P<0.01) compare to other treatments in SGR but no significant difference were observed among themselves (P<0.05). Cortisol concentrations came up in compare with control treatment at the end of the starvation (Day 29) (P<0.05) but no significant trend were observed among the treatments during refeeding period (P>0.005). According to the effects of handling and environmental on cortisol changes could be suggest should be reduce handling and stress to achieve distinctive results.

we conducted this survey to identify sea cucumber species in Chabahar Bay (Oman sea). Four stations were selected according to previous pilot study around the bay between 4 to 12 m depths. Sea cucumber species were counted in 200 m2 with four replications in each station using SCUBA equipment. Species identification using key external characteristics as well as the spicules. Four species including Holothuria leucospilota, H. hilla, H. edulis, Stichopus hermanii, were identified that belong to Holothuroidea and Stichopodidae families. Maximum of density, Shannon-Wiener and Margalef richness index observed in winter and minimum in summer. Evenness Index also indicates equal distribution of sea cucumbers during seasons and regions of the study.

Gonapodasmius epinepheli, a didymozoid trematode, was found in orange spotted grouper (Epinephelus coioides), in south coast of Persian Gulf (Khark Island, Bushehr) in Iran. The parasite encysted on the primary lamellae of the gills. Histopathological sections revealed that larvae were primarily embedded underneath the gill epithelium and eggs of the parasite were distributed in some organs such as gill epithelium, heart and macrophage centers in the head kidney. Pathological changes and host response were shown mainly on gill lamellae, e.g. reduction and destruction of secondary lamellae. In this report, the life cycle of this parasite and it is histopathogenesis are discussed.

41 fish were collected from March 2008 to May 2009. The fish was catched by gill-net and transported to fisheries laboratory after fixing by formalin (10 %). The objective of the present study was to determine the composition of Schizothorax zarudnyi diet and study of it's different biotic factors such as morphology, gonado-somatic index, fecundity, condition factor, relative length of gut, feeding intensity, length and weight abundance. Mean length and weight of fish were 22.35 ± 3.49 cm and 121.70 ± 57.07 g, respectively. The sexual ratio was 1.1:1 (male: female). Mean, maximum (in March/April) and minimum (in May) of gonado-somatic index were 1.05 ± 0.67, 1.74 and 0.60 %, respectively. The GSI showed an annual breeding cycle for this fish with March/April as breeding season. Mean relative and absolute fecundity calculated as 33140 ± 1905.65 egg per kg and 26964 ± 1001.97 eggs, respectively. Mean, maximum (in April) and minimum (in May) of condition factor were 1.01 ± 0.12, 1.30 and 0.76, respectively. The ratio of relative length of gut to body length was 1.73 ± 0.30. Totally, with a RLG more than one, this fish is omnivorous with higher tendency to herbivorous. Investigation of fish gut showed feeding habits revolved around crustaceans, mollusks, yellow, brown and green algae, higher plants, detritus, sludge and specially Gambusia fish. Mean of feeding intensity (IF) was 180.64 ± 108.99 %. Maximum and minimum IF was found in May and March with 480.54 and 43.02 %, respectively. The regression equation between length and weight was as W= 0.0058 L3.177 with r=0.98. Regarding to b amount in aforementioned equation, fish has a positive allometric growth.

Class Larvacea is belonging to phylum Chordata and sub phylum Urochordata. Larvacea or appendicularians are marine organisms, holoplanktonic and filter feeder. Their feeding is done by filtration of through their house. Hormuz Island was chosen because of its special position and staying between Persian Gulf and Oman Sea. Due to this geographical position, despite different density, distribution, diversity and other spatial and temporal factors, there are species of both regions at there. Zooplankton samples were taken seasonally (every 40 days) starting from July 2007 to May 2008. Periodic sampling was applied using of plankton net with mesh size 300mm. Plankton samples were collected from four localities (South, North, East, and West) of the Island, each one with two stations, one in the vicinity of the coastal water and the second away from it. Seven species of Larvacea were found (Oikopleura dioica, Oikopleura longicuada, Oikopleura fusiformis, Oikopleura rufescence, Oikopleura huxleyi, Stegosoma magnum, Fritillaria formica f.digitata). This study showed that temperature affects plankton distribution as an important factor in Hormuz Island water. The result showed significant relation between temperature and density of Larvacea.

Pollutants especially heavy metals entered into environment both naturally and human activities such as extraction, transportation and processing of petroleum materials causes to destroy the environment. In this research assessed the concentration of heavy metals (Cd, Pb, Cu, Co, Ni) in the muscle, liver and gill tissues of Tenualosa ilisha in the mouth of Arvandrood from northwest of Persian Gulf, in spring 2008. The fish samples were caught using gillnet. After biometrical measurements, the muscle, liver and gill tissues of 35 randomly selected fish were separated; metals were extracted from the tissues using chemical digestion method with pure nitric acid and their concentrations were determined by AAS. Analyzed results using Pierson correlation showed that is a positive linear relationship between accumulation of Cadmium, Cobalt and Nickel with total weight and standard length factors (P< 0.05). There was no significant relationship between accumulation of Lead with standard length (P-Value= 0.456) and total weight (P-Value= 0.520) and Copper with standard length (P-Value= 0.479) and total weight (P-Value= 0.373) factors. Mean concentrations for Cd, Pb, Cu, Co, Ni (0.119±0.034, 1.013±0.027, 2.309 ± 0.823, 0.867 ± 0.330, 4.004 ± 2.701 ppm/dry weight) were compared with the international standards by using t-test and assessed the content of some metals upper the permissible limits proposed.