JOURNAL OF MARINE BIOLOGY
Year:2013 | Volume:4 | Issue:16|Papers Count:12

This investigation was conducted in order to standardize (to modify) the pot size for spiny rock lobster, Panulirus homarous by designing appropriate escape vents in terms of position and size to allow the escape of immature lobsters (CL£70 mm). The lobsters were examined by comparing experiment in four kind of trap with common fisherman trap as control. A location of study was laboratory-based utilizing concrete flow-through sea-water "raceway" tanks. Carapace lengths (CL), Width (CW) of Lobsters that use in the research were 56±5.13 and 45.8±4.93 mm respectively. The Lobsters were grouped according to 5 mm CL classes for a range of 45–70 mm by placing 2 lobsters of each size class range in the pot. Each pot was monitored in the experimental tank or sea for 24 h soak time to measure the number of lobsters escaping and remaining inside. Result of ANOVA analysis indicated that the escape characteristics of each treatment trap type were significantly different from the control traps (p£0.05). Comparative average escapement between the treatments and the control showed significantly differences. Observations in comparing the average percent escapement between treatment 4 with T3 and T2 were not significant (P³0.05). Relationship between carapace length (CL) and carapace width (CW) of lobsters used in this research was indicated that, 71 mm escapement vet is superior. As we expected, result of this research indicated that increasing the vent size, decrease vent height and position of vent that was close to the bottom of trap were more effective to escapement of sub- legal lobsters and to decrease the retention in trap. As a result of this research, for lobsters with 70 mm carapace length, as legal size, the best choice is treatment 3 with 71 mm escape vent. Also the vents located at the bottom of trap were better than the other types.

This investigation was carried out at the Shahid Bahonar Kalardasht Salmonids Reproduction Center (KSRC) during spawning season during 2009. A total of 30 mature males of wild salmon (Salmo trutta caspius) were used. In the first step all of male brooders (30 male) striped separately and 13 female striped eggs. Fertilization was made with mixing sperm and the eggs. After the eggs hardness process the eggs transferred to in a incubator, then the incubation process trends were evaluated. Eight days after the first step, the second step of sperm stripping occurred and 17 days after the second stage, third stage of sperm stripping was done. Similar to the first phase sperm stripping and fertilization was repeated and 25 male with 10 female for second stage and 15 male with 7 female for third stage. At the end of each three stages of sperm stripping, sperm density, spermatocrit percentage, sperm volume, sperm motility and morphology of spermatozoa (percentage of abnormal spermatozoa) were recorded and investigated its effect on fertilization rate, eyed eggs, hatching rate and larvae survival during repetitive sperm extraction were measures. The results showed that there were significant differences between the volume, motility and sperm morphology during third phase of the study (P<0.05). The highest fertilization rate (96.29%), eye spot time rate (91.52%) and hatching rate (93.82%) observed in the first stage of sperm extraction and lowest observed in the third stage of sperm extraction. In this study, sperm density, spermatocrit, and survival rate until the absorption of yolk sack stage in all the three stages were  not significantly different (P>0.05).

The economic value of grouper in aquaculture industry as well as existing of threatening environmental factors in their natural habitats of this fish has led to an increase in importance of captive breeding of this species. In this study, the efficacy of semi-artificial propagation of orange-spotted grouper in Khuzestan province has been investigated. In this respect, eight breeders, including four males and four females, were transferred to the Center of Marine Fish Propagation. After anesthetizing, the morphometric parameters, including total length, standard length and body weight have been recorded. Simultaneously, ova were checked for their quality. All fish were hold in ratio of 1:1 (male to female) and breeding was performed at midnight without hormonal injection. At each spawning time randomly thirty eggs were collected and egg diameters and fertilization rate have been determined. Other related parameters to breeding efficacy, including hatching rate, larvae length and larvae survival rate were measured in an appropriate time. The obtained data show that fish having higher length and weight produced more ova, eggs and larvae in size (P<0.05). In this study, the maximum amount of fertilization and hatching rates were estimated as 98 and 88% respectively. Survival rate of larvae were also determined until yolk sac absorption time and its amount was not more than 20% in all cases. Using regression analysis, ova and egg diameters showed significant relationships between the total length and body weight. Moreover, larvae total length; total width; yolk sac length and oil globule diameter have been also measured and discussed in this manuscript.

In order to evaluate the effect of noise on some of growth factors and survival rate of Acipenser nudiventris fry a 40-day experiment was done through a completely randomized design framework with three repetitions. Ninety fish fry with the initial average weight and length of 18.7 g and 14.9 cm were considered. Thirty fish was considered as control and held in the voice intensity of 60 dB and the two other treatments were hold in the voice intensity of 80 and 100 dB. The Fish fry were tested in nine 45´40´70 cm glass aquariums filled with water. The biometry of the fish was performed every 10 days and the weight, length, specific growth and survival factors were evaluated. ANOVA and Danken test indicated a significant difference between the mean weight, length, specific growth and survival rate in the end of the study. The control group mean total length was 18.73±0.27 that was higher than two other groups (15.90±0.05 and 15.31±0.01 respectively. The Condition factor, which was the lowest for the control group, also showed statistically significant difference (P<0.05).

The study investigated the relationship between some of biological parameters (p hytoplankton, zooplankton and Mnemiopsis leidyi abundance) and some environmental parameters (temperature, salinity and water clearness) in the southern Caspian Sea during 2009 to 2010. Sampling was performed in four seasons (spring, summer, autumn and winter) and at eight transects perpendicular to the coast. Phytoplankton and environmental parameters samples were collected using Niskin. Zooplankton and Mnemiopsis leidyi samples provided by net. Total of 384 phytoplankton and water samples and 160 zooplankton and Mnemiopsis leidyi samples were collected at the euphotic zone from depths of 5, 10, 20, 50 and 100 m. According to results, minimum and maximum values of phytoplankton biomass were observed in summer and winter, respectively. During spring and winter, the abundance of zooplankton was in highest level and conversely the minimum values observed during summer and autumn with obvious increasing in M. leidyi abundance.  Maximum temperature and salinity were observed in summer and autumn, respectively. Result on PCA analysis in summer showed that decreasing of salinity had positive effect on M. leidyi and zooplankton abundance especially coppepoda and cirripedia groups. In this season, phytoplankton biomass was affected by temperature and salinity. However, with considering PCA analysis in autumn, phytoplankton biomass was correlated with PC1 which had a principal rule as compared to zooplankton. In this season, M. leidyi abundance was correlated with temperature and salinity of water. M. leidyi abundance was negatively correlated with water transparency during the two periods of time. It can be due to mucus excretion of  M. leidyi which may decrease transparency of the water. In this study for the first time the dynamic population of M. leidyi is used as key factor in the Caspian sea ecosystem events, however the interaction of different factors such as biotic and environmental parameters may also have effect on changes of dynamic of zooplankton abundance and its groups composition.

The fish in farming systems are stocking in higher densities than in the nature. Proper stocking density has marked effect on the growth of the fish. The purpose of this experiment was to determine the effect of different densities of Rutilus frisii kutum fry in eight weeks study on growth. The experiment conducted on five densities (three replicate each) as following: 10 fish (0.174 kg/m3), 20 fish (0.348 kg/m3), 30 fish (0.522 kg/m3), 40 fish (0.696 kg/m3) and 50 fish (0.870 kg/m3) in 20 l water. Feeding rate was 10%, based on the total weight of the fish. The results showed that there was significant difference between the amount of body weight of the fingerlings in different treatments (P<0.05) so that the maximum weight and length was seen 30 fish/20 l (0.522 kg/m3) density. Also, there was a significant difference in FCR, SGR. BWI%, GR, CF and survival rate between different treatments (P<0.05). The results of this study showed that the best stocking density for Rutilus frisii kutum fry is 350000/ hectare that may favorite optimum use of the pools for releasing the juveniles to the sea for restocking purposes.

In this study during year 2010 to 2011 total of 300 specimens of 5 marine fishes including Otolithes ruber, Epinephelus coioides, Acanthopagrus cuvieri, Lutjanus malabaricus and Pampus argenteus. from fish markets of Ahvaz and Abadan were collected. A total number of 50 specimens from each species were randomly collected from fish markets and transported to microbiological laboratory using plastic bags in ice. External lesions of the fish were studied. Many bacteria were isolated from skin, fins and head and totally 75 isolates were successfully isolated from fish. The results showed the most infected lesions were in skin with abundance of (45.3%) and then the fin (24%). The bacterial species isolated were Aeromanas spp., Aeromonas sobria, Aeromonas hydrophila, Staphylococcus aureus, Pseudomonas spp., Pseudomonas aeruginosa, Acinetobacter lowffii, Enterobacter spp.,Escherichia coli and Enterococcus spp. Between the isolates Aeromonas spp. (17.4%) and Pseudomonas spp. (16%) were the most abundant species (in the all bacteria isolated) and Enterobacter spp. 1.3% had the least prevalence. Gram-negative bacteria were recognized as the most prevalent bacteria in this study. Many factors could contribute to human bacterial infections namely poor water quality, handling, transportation, poor hygiene and season. So, health management is mandatory to keep water in good quality and suitable density and take a good care of it in order to control the bacterial agent. In the case of poor hygiene, the contamination of fish and fish products may increase due to unsanitary procedures, the rotation of the assigned duties of workers, and airborne microorganisms during packing of the product.

This study has been done at two stations in Talar river, Mazandaran during Oct. 2008 to Sept. 2009. The purpose of this study was assessment of morphology and population structure of Cobitis taenia in Talar river. Samples were collected and killed using electro shocker (300 V). The fish were fixed in%10 formalin. A total of 410 specimens of Cobitis taenia were examined and 6 meristic and 38 morphometeric factors were investigated. Results showed that in this river the fish has not hard fin rays. The fish has 6 soft rays in dorsal fin and 5 branched rays in anal fin, 39 vertebra, 18 gill rackers and also the average length of head was 10.42 mm. Head width was 5.49 mm and height of head was 6.95 mm, distances between eyes was 3.01 and height of body was 8.46 mm. The length of caudal peduncle was 5.35 and length of dorsal fin was 17.50, height of dorsal fin was 4.64. The length of pectoral fin, length of pectoral fin and height of pectoral fin were 9.77, 3.98 and 7.94 mm respectively. Generally the proportion of fishes has been reviewed. 29% of females and 38.5% of males and 32.4% of immature fishes have been studied. The 4 numerical meristic and 5 morphometric factors had significant differences between two stations (p<0.05) and%30 of the factors had significant differences. The review of population structure of Cobitis taenia has been shown that mean age of the fish has been 1.07 year. The equation for male W=0.671´TL+0.043 and female W=1.593´TL+0.061 has been determined for correlation between total length and total weight of the fish.