Journal of Aquaculture Development
Year:2016 | Volume:9 | Issue:4|Papers Count:8

In this study, histological characterization of male gonad of wels, Silurus glanis, were investigated over a period of one year in Anzali Wetland. The testes of 196 male specimens that were caught in different sizes by traps were fixed in Bouin’s solution. Then samples were prepared by classical methods of histology with Hematoxylin and Eosin (H & E) staining and studied by light microscope. Also, the gonadosomatic index (GSI %) were determined during the sampling period.  Six testicular maturation stages were observed including: immature (I), early developing (II), late developing (III), ripe testes (IV), running ripe testes (V) and spent (VI). Spermatogenesis was done during a relatively long period of one year. The stages IV and V and sperm production were occurred from late February to early June and stage VI was from June to early August. The maximum mean value of GSI% were due to late May and early June. This index decreased clearly in July. The results showed that spermiation was started in late June and resumed to late August.

This study was conducted in order to survey the socio - economic effects of rice and fish cultivation development in the Guilan province. Statistical population in this study were all farmers in Lahijan and Astaneh Ashrafieh who farmed rice and fish mixed culture. It was a running survey which 102 samples were selected. 63 field from Astane Ashrafeye and 39 field from Lahijan formed sample volume. The data were collected through questionnaires. Results showed that the most important effects in the rice-fish cultivation development in the Guilan province were included; increase in the level of food protein because of dietary protein came from fish consumption, increased education and awareness of rural, happiness for development in the lives of rural, rural commuting into cities and other villages, people's participation in rural development programs, reduce fertilizer and pesticide monoculture than in cultivation, increase rice yield, conserves water resources, labor force required to reduce weed farms and  quality of rural food.

In this study the toxic effects of Nodularia, a cyclic pentapeptide hepathotoxin, on plasma enzymes including aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were studied. Nodularia is produced by Cyanobacterium Nodularia spumigena which is mainly found in salt and brackish waters. Salmo trutaa caspius were exposed to Nodularia in two different doses (1×104 and 1×108 cells.ml-1) for 12, 24, 48 and 96 h and then fishes transferred to clean water for 8 days. LDH enzyme activity indicated significant differences at different times in high concentration and showed significant differences than control group in 12, 24 and 96 h after exposure to toxin in the high-dose group and in 12 h post exposure in the low-dose group. LDH enzyme activity in the high-dose group significantly higher than low-dose group in 12 h post exposure. AST activity indicated significant differences in the high-dose group at the different times, but this changes were not significant than control group. No significant differences were observed in recovery phase. This study indicated that LDH activity is a more appropriate indicator than AST for effects of exposure to Cyanobacterium N. spumigena in this fish.

One of the problems for rivers in Iran is related to dispersal of the waste effluents from trout farms to them and Shemrood River is one of them, a center for trout farming in Guilan province which includes four main active parts. Thus in order to evaluate the effects of trout farm effluents on the river, the macrobenthos communities of selected parts of the river was analyzed. Eight stations mainly located near the wastewater inlets and outlets were selected then sampling was done on macrozoobenthos communities, they were identified to family or genus level, counted and evaluated by ecologic and biological indices. Results show that thirty-four taxa groups of benthic samples such as worms, mollusks and different orders of aquatic insects have been observed by an average number about 12.65 ± 4.77 numbers per square meters. Also mean amounts for BMWP, ASPT and the Hilsenhoff Index (HFBI) were determined afterwards. BMWP index was acceptable for outlet stations but the amounts of EPT% and EPT/Chiro had been decreased in these stations. In addition benthic biomass has been increased after the outlets. In conclusion, it can be said that the effect of dispersal of the sewage from trout farms on Shemrood River is not significant and indicates the ability of the river for self-purification.

In this survey polymorphism of SLC24a5 gene of Rainbow trout (Oncorhynchus mykiss) was studied. Samples were prepared from 100 Rainbow trout muscles. After DNA extraction, part of gene from polymorphism area with 1000 bp amplified by PCR then cut with Taq1 inhibiting enzymeand electrophoresed on agarose gel 1.5%. Results shows that M and N alleles are in this area of gene, and the frequency of them is 0.72 and 0.28 in population respectively. MM and NN genotypes were distinguished which frequency of them were estimated 0.72 and 0.28 in whole population respectively. Chi-Square test for this part of SLC24a5 gene was not similar with Hardy–Weinberg equilibrium. It shows non-random mating, small population and increase in inbreeding and homozygotes increase in the population of this study. Furthermore Rainbow trout is so important in aquaculture industry in Iran the notability of this issue is significant because SLC24a5 gene is highly inheritable and selection of that can improve the color of meat.

This study was conducted in order to prioritize the affecting factors on non-adoption of fish farming in rice fields in Guilan province. This research was conducted in two step in 2009 and 2014 that statistical population were rice farmers of west Guilan province. Sample size in first step of study was 123 farmers who were unwilling to adopt rice and fish mixed cultivation lived neighborhood fields of rice and fish farming. In second step of research, 10% was added to the first step sample size and then 135 people were studied randomly outside the adopters region. The data analysis in first step of research was conducted by multiple response analysis. Also, data in the second step of study was to prioritize using analysis of triangular fuzzy numbers. Result showed that the main limitations for adoption of fish farming in rice fields by farmers were included: absence or lack of security provider organ to prevent of of stealing fish, lack of access to financial services with an emphasis on long-term loans with low interest, rice fields of non-enclosed and problems arising it, the lack of responsible organization for integrated rice-fish farming, Lack of initial funding for the establishment of fish sanctuaries and high costs, Lack of knowledge and information in relationship with rice and fish farming, lack of basic amenities such as deep or semi-deep wells and electricity power, and Long-distance of farmers home from rice paddy.

This research was conducted to study the body shape changes and morphological development of spare Sobaity (sobaity sea bream) (Sparidentex hasta), a valuable economical species, during early development from hatching up to 35 days post hatching (DPH) using geometric morphometric technique. A total number of 531 larval specimens were collected from different days. For extracting body shape data, the left side of specimens was photographed. Then nine homologous landmark-points were defined and digitized on 2D pictures using tpsDig2 software. Landmark data after GPA, based on procreates analysis analyzed using Relative Warp. The results showed that change of body shape in spare Sobaity during early development includes increasing depth and length of head, development of caudal region and increasing body depth, respectively. The cluster analysis was performed based on body shape of larval specimens using Ward’s algorithm, to identify clusters between age or size groups and the results revealed that larval stages of Sobaity can be divided into five stages including (1) early larvae, (2) larvae, (3) post larvae, (4) younger juvenile and (5) juvenile. Also, based on our finding, the body shape changes of this species during early development is due to adjusting of vital priority.

The Kutum, Rutilus frisii, is the most important bony fish inhabiting the South of Caspian Sea so that the populations of autumn form gravely shrinked and neared to be extinct. This research implemented to finding of artificial reproduction biotechnic and restocking damaged population of autumn form Kutum in Caspian Sea. The autumn form of Kutum brooders caught from Bandar Anzali harbor to entrance Nahang-Roogah River in Anzali Wetland. The brooders held in two different conditions include of floating cages in Anzali Wetland and earthen pond for adaptation and complete gonad maturation. Male to female ratio was 1 to 1.4. Minimum and maximum weight were 1450 g and 3100 g with average of 1850 g in female and 670 g and 1900 g with average of 1165 g, respectively.  For artificial spawning, male and female brooders injected by carp pituitary extract with dose of 2-3 and 4-5 mg/kg body weight, respectively. Mean number of absolute, practical and relative fecundity determined as 88565±16809, 73805±14008 and 48670±12056. Dry method used for eggs fertilization, mean of fecundity was measured 97.3±3.2% and incubation period lasted 7 to 10 days in temperature of 14 to 16oC. Larvae introduced into fertilized earthen ponds (500 m2) in intensive condition (3 million /ha). Period of the larvae nutrition and fries culture in earthen ponds lasted 3-4 months. Finally, autumn form kutum fingerlings of 1-2 g produced and released into Anzali Wetland to its restocking for first time.