Population dynamics and reproductive biology of crayfish (Astacus leptodactylus Eschscholtz, 1823) in Shorabil Lake (Ardabil Province), northwest of Iran

Freshwater crayfish (Astacus leptodaciylus Eschscholtz, 1823) is a very valuable macrobentic organism which was introduced Aras reservoir to the Shorabil Kake in the amount of 15000 specimens during the years 2002-2006. This species produce very good population in the Shorabil Lake. We investigate biological, biomass and MSY of the crayfish in the Lake during the years 2006-2007. Results showed that the mean total lengths and weight of this crayfish for both sexeswere 82.5±32.4mm and 82.5±32.4g, respectively. Maximum total length and weight of the caught crayfish was 196mm and 328g respectively. The sex ratios of male:female crayfish caught with a funnel trap of 10mm mesh size (stretched mesh) were estimated at 1:2.4 that was significantly difference from :1 ratio ( X2 = 479.01 ; P<0.05 ). Mean number of ovarian and pleopodal eggs were estimated at 396.6136.5 and 311.11±22.92 eggs with 95% confidence limits, respectively. The time of the first molting of the male stared from beginning of the May at a water temperature of around 14°C and ended in mid-June. The second molting of the male and the first molting of the female is done simultaneously and started in beginning of the October at a water temperature of around I 7°C. Reproduction period of this species started from beginning of the December and lasted until the mid-June in Shorabil Lake

Analyzing the effects of aquaculture and rebuild aquatics stocks on fisheries development in the Caspian Sea

Using SWOT analysis with traditional matrix and quantitative matrix methods, the strategies to benefit from strengths and opportunities to vanishing weaknesses and decrease of threats for strategic management of aquaculture in Iranian Northern provinces was surveyed. Utilizing researches held in fisheries research centers and existence of aquaculture experts in vicinity, activation of veterinary organization in production and post production, and entering new brood stocks with desirable growth are the main strategies for developing rainbow trout and Chinese carps culture in Iranian Northern provinces. In sturgeon fishes culture, independence of farms from fingerlings produced by governmental complex and diversification the cultured fishes using new species and hybrids can develop this part of aquaculture. Avoiding illegal fishing in sea and rivers, preserving the population of Caspian Sea fishes, entering new fish species which their resources are decreased extremely to breeding and fingerling production cycle, and using pike perch and bream while they migrate to Anzali Lagoon from Caspian Sea, instead of freshwater brood stocks will cause the output of sea enhancement and sea ranching activities to increase, and fisheries return coefficient of these fishes will rise. Using quantitative matrix and scoring method, it was defined that aquaculture in Iranian Northern provinces are extremely approved and acceptable and the score of strengths is more than weaknesses and opportunities more than threats. By using strategic management, these activities can be more developed

Study of parasites occurrence and intensity in fishes of Anzali Lagoon

Tish survey prolonged from summer 2011 trough summer 2012. During this period 574 samples of different fish species were investigated for their parasites. Totally 30 species of parasites isolated of the fishes. Some of the isolated parasites are recorded for the first time in Iran. Rafidascaris acus Orientocreadium siluri, Silurotaenia siluri, Acanthocephalus lucii , Argulus foliaceus has recorded for the first time from European catfish, Silurus glanis, and Dactylogyrus inexpectatus has recorded for the first time from Gibel Carp, Carassius auratus gibelio, in Anzali wetland. Statistical comparison of parasites infections and intensity between the different area of Anzali wetland were done. Infection of Pike, Esox lucius, to Diplostomum spathaceum, Raphidascaris acus and Monogenean in western parts of wetland were significantly different from the Eastern and Central areas (p<0.05). So based on the data have concluded the eastern and central regions of the wetland are more polluted than the western part. Comparing the results of the present study with before ones showed that the composition of parasite species has been changed over time, while the prevalence, intensity and abundance of parasites have been increased. It may be due to changing environmental conditions such as increasing discharge of effluent, eutrophication of the wetland. This results accents to necessity of reconstruction of Anzali wetland with preference of eastern and central regions

Study on biology (age, feeding and, reproductive) of (Cyprinus carpio, Linnaeus 1758) in south coastal line Caspian Sea (Iranian waters)

The Caspian Sea is the biggest lacustrine water source. Common carp is very important commercially in south coastal line of Iranian Caspian Sea waters, especially in east coastal line, because eighty percent annual catch of this species has been caught in this area in particular. Despite the common carp importance and value in Iran, but there is a little information about its biology in natural system. This study is comprehensive research on reproduction, growth and feeding. The specimens were caught by beach seine net in coastal line of Iranian waters. The fork length ranged between 5.6 and 2866.2 g. The b value of the length-weight relationship ranged from 2.843 to 2.924 for female and male, respectively. The age composition of the specimens was from 1 to 11 year. The Gonadosomatic ratio (GSR) changed from 2 to 12. There were two peaks of GSR in April and December, so that the latter peak was much shorter than the first that. Fecundity variations were high and ranged 77448 to 430745 eggs. It observed linear significant correlation in fecundity- weight (r=0.98) and fecundity-length (r=0.88) relationships. Average growth in length was described with the Von Bertalanffy growth model: L (t) = 60.5(1-exp (0.19(t-0.65). The percent of empty stomach and prey dominant evaluated during different seasons by specific formula result showed that in Cyprinus carpio prey Molluscs was dominated and specific food items. Empty stomachs in winter and spring were higher and lower, respectively

The survey of Khandaghloo dam reservoir of Mahneshan city of Zanjan province

Reservoirs are one of the most constructions for control and water supply for different usage that could have various social an economical effects. The Khandaghloo dam reservoir with area of 100 ha located in Mahneshan city of Zanjan province and related to Parichay river watershed. Khandaghloo reservoir is valuable water body that the aim of its establishment was supply of water for agriculture farms. The reservoir has been studied for responsible and sustainable fisheries exploitation proposes. Results showed that the reservoir categorizes as eutroph to super eutroph based on different indices.Also phosphorous is limiting factor of the water body.Totally 42 genera from 6 phyla including green-blue algae cyanophyta, diatoms (Bacillariophyta), green algae, chlorophyta, euglenophyta, pyrrophyta and xanthophyta has been identified and cyanophyta was the dominant group that comprise 74.3 % of phytoplankton population. The zooplankton of the reservoir comprised 4 phyla and 20 genera. 1 genera of the protozoa and rhizopoda, 1 genra of the ciliophora ,15 genera of rotatoria, 2 genera of cladocera has been identified in zooplankton communities. Tubificidae and chironomidae has been identified in all months of the survey. The mean total length of crayfish was 130.5±20.5 mm ( 636) and mean weight was measured as 69.4±34.1 g with maximum and minimum weight of 1.9 and 207.2 g respectively .Total biomass of crayfish in Khandaghloo reservoir estimated as 3.4 tones with a range of 1.1–5.7 tones. But it is recommended not to harvest for at least two year due to high mortality of the populations.The fishes of the reservoir comprised common carp Chinese carp (silver carp, big head and grass carp) (released), Caspian kutum (accidentally released by fishery sector) and some endemic species as Siamahii. The catch of the reservoir fluctuated between 8 to 26 tones during 2000-2010.The fish production of Khandaghloo reservoir ranged from 167 to 324 kg/ha based on different methods that by consideration of 100 ha area of the reservoir, the total production of fish fluctuated between 16.7 to 32.4 tones. The fingerling restocking of Chinese carp in Khandaghloo reservoir with density of 1500 fingerling/ha recommended as 68% of phytoplanktonivorous fish (silver carp) ,12% zooplanktonivorous fish (big head), 6.6% of Crass carp and 10% of benthophagous fish (common carp)

Study on the growth status of mullets with viral nervous necrosis disease in the southern Caspian Sea

Mullet and mullet products have considerable economic importance at a regional level, especially around the Caspian Sea. The leaping mullet constitutes an important part of their production. This study is the first detailed work on the age and growth of the leaping mullet (Liza saliens) from September 2012 to March 2013 in the Southern coast of the Caspian Sea. Age and growth determinations were based upon the scale samples taken from 102 fish. Marginal increment analysis was used to validate age determination. The back-calculated lengths stage estimated from the scale showed no differences between in this study. The maximum age of leaping mullet in the Southern coast of the Caspian Sea was 5 years for males and 6 years for females. The von Bertalanffy growth functions were Lt=30.415(1-e-0.275(t+0.645)) for males and Lt=34.832(1-e 0.211(t+1.009)) for females. A large spread and length overlap characterized the age groups. The estimated Length Weight relationships were common for the two sexes (W=0.079L3 ). The slope (b) values of the length-weight relationship showed that weight of leaping grey mullet in Mazandaran increased associated with length in isometric. The mean condition factor for males, females and all specimens were determined as 0.908, 0.900 and 0.897, respectively. According to sex groups, the mean condition factor of males was slightlyhigher than that of females. The total length for leaping grey mullet was determined as 23.3 cm

Study on viral nervouse necrosis (isolation, characterisation and pathogenesis) in golden grey mullet in the Caspian Sea and study of pathogenecity and possibility of transmission to the other fish species (Sturgeon fishes, Rutilus frisii kutum and reared Rainbow trout and Carp)

Study on Viral Nervouse necrosis (isolation, characterisation and pathogenesis) in Golden grey mullet in the Caspian Sea and study of pathogenecity and possibility of transmission to the other fish species (Sturgeon fishes, Rutilus frisii kutum and reared Rainbow trout and Carp) Viral Nervous Necrosis (VNN) is a worldwide disease affecting several species of cultured marine fish. For the past two decades, betanodavirus infections that cause Viral Nervous Necrosis (VNN) have emerged as major constraints on the culture and sea ranching of marine fish in almost all parts of the world. More than forty species mainly of marine origin have been so far affected and this number is likely to rise in future following the introduction of new species and the increase of aquaculture trade. Unknown acute mortality occurred in wild golden grey mullet Lisa auratus and Liza saliens in Iranian waters of Caspian Sea in recent years. In order to isolation and confirmation of causative agents of golden grey mullet mortality in the Caspian Sea, a complementary research investigation project was designed in 2005 and approved immediately in Iranian Fisheries Research Organization (IFRO). Many diagnostic aspects such as Virology (Cell culture and Elctereone Microscopy), Hemathology, Bacteriology, Histopathology, Molecular biology (NestedRT-PCR), Heavy metals measuerment and Serology (IFAT and IHC) were employed in mentioned multidiciplinary project. About 322 moribund fish samples which revealed skin darkening, erratic swimming behavior such as spiral and belly-up at rest and high distention of swimming bladder. Suspected samples were collected from coastal capture sites in iranian north proviences in 2006 till 2009. Targets tissue such as brain and eye were removed in strile condition and then kept in -80oC frezzer for cell culture and Nested-RT-PCR. Other tissue samples from liver, kidney, intestine, stomach, gill, skin and muscle, gall bladder and gonads were taken and fixed in 10% buffer formalin and same parts fixed in glutaraldehyde 3% for histopathology, IHC and EM respectively. Cytopathic effect (CPE) was observed in those cell cultures just six days after inoculation with the dilutions of the tested 312 homogenate supernatants. CPE in monolayers of cells cultured (SSN-1 cell line) was characterised by thin or rounded, refractile, granular cells with vacuoles. Nine samples were positive in virology assay. Nested- RT-PCR was done on suspected tissue samples and supernatant of CPE positive samples and 21 tissue samples and all CPE positive samples were positive. IFAT was selected as a confirmatory method for identifying viral strains replicating on cell cultures and carried out with rabbit anti-betanodavirus serum on suspected tissue samples and some smears of CPE positive samples. Some bright points approved betanodavirus antigen and confirmed cell culture and Nested-RT-PCR findings. In fixed tissue samples widespread and massive vacuolation were observed in brain, spinal cord, retina and optical nerve. In order to confirmation of diagnostic findings , IHC was done with monoclonal antibody antibetanodavirus and some red-brown points were observed. Theses findings revealed expected viral antigens and confirmed previous results. Moreover, virus particles with 25-30 nm in diameter were visualized in infected brain and retina using positive staining in TEM. Also pathogenicity test was employed to confirm the obtained results. So Guppy fish Poecilia reticulata and sturgeon fry were used instead of the experimental host due to ease of handling and susceptibility. After 15 days post infection, guppy bathed in VNN-infected tissue culture with 104 TCID50 showed clinical signs similar to naturally infected Golden grey mullet, and the mortality rate reached up to 100% in 75 dpi. When target organs were examined by cell culture isolation, serology, and histopathology, all revealed the presence of virus in the Guppy. Suspected supernatant injected to sturgeon fry through intravitreous injection and widespread vacuolation were observed in brain and spinal cord buy IHC and Real time PCR were negative. In conclusion, with attntion to obtained results in this investigation such as ecological factors, clinical signs, histopathological, virological and bacteriological results, molecular analysis, (IHC, IFAT, PCR), TEM demonstration, serological and hematological findings, it could be confirmed that VNNV was the main causative agent for disease outbreak in Golden grey mullet in Southern coastline of Caspian Sea