Iranian Journal of Fisheries Sciences
Volume:4 Issue: 2, Jan2005

During the period from August 1997 to March 1998, two thousand samples of cultured Penaeus semisulcatus postlarvae and subadults were collected from five hatcheries and 20 growout farms distributed in three provinces along the costs of Persian Gulf and the Oman Sea. Based on growth signs, LM and TEM histopathology, Hepatopancreatic Parvo-like Virus (HPV) were identified from the samples. The HPV particles most often appeared in spherical, but occasionally in angular forms. The particles in hepatopancreatocyte sections, averaged 22-24nm in diameter.

Thirty three Gyrodactylus spp have been found on the gills and body surface of both wild and farmed freshwater fishes in Iran. Among them nine species have been identified up to the species level, which are new locality records. The identification of the others, mainly belong to endemic wild freshwater fishes, need further studies. Among the known species, Gyrodactylus derjavini (Mikhailov, 1975) has been found on the gills, caudal and anal fins of the Caspian salmon (Salmo trutta caspius) and rainbow trout (Oncorhynchus mykiss). These species are very harmful to salmonid fingerling production industry of Iran. In warm water cultured fishes, G. sprostona, with widest host range, infects common carp (Cyprinus carpio), Silver carp (Hypophthalmichthys molitrix) and big head carp (Aristichthys nobilis) in almost all fish farms of Iran. Other species, which will be discussed here from their economic importance and host specificity points of view, are G. cyprini, G, elegans, G, fossilis, G. kobayashii, G. prostae, G. shulmani and G. stankovici. Furthermore the pathogenecity of Gyrodactylus spp are discussed and new technology (DNA sequence) for precise identification of parasites is also recommended.

During a parasitological investigation on the fresh water fishes of North West of Iran (West Azerbaijan Province), 266 specimens of 11 fishes were examined. Fishes were collected from seven stations from Aras, Zangbar and Sarysou Rivers between summer 2001 to summer 2002. Nine protozoan species were detected; eight Cilliophora and one Rhizopoda. Cilliophora are: Chilodonella sp.,Apiosoma sp.,Vorticella sp. Ichthyophthirius multifiliis, Trichodina perphorata, Amphileptus branchiarum, Tetrahymena pyriformis, Stylonchia pustulata, and the Rhizopoda species is Arcella vulgaris. Results show that five of those species are for the first time being reported from Iranian fresh water fishes

An acute mortality caused by an uncertain agent occurred in wild golden grey mullet (Liza auratus) population in the Iranian side of the Caspian Sea in February, 2004. Clinical signs of the moribund fish were erratic behavior such as spiral swimming, belly-up at rest and over inflation of swim bladder. Histological examination of brain of dead fish revealed hyperaemia, degeneration and necrosis in external granular layers as well as focal extension in intestine. Severe leucopenia was also observed. No putative causal factors were suggested by bacteriological, parasitological or environmental examinations. In virological examina-tions, however brains of affected golden grey mullet were positive in the reverse transcriptase-polymerase chain reaction test for piscine nodavirus (Nodaviridae, Betanodavirus), the causative agent of Encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN) in a variety of cultured marine fishes worldwide. Nucleotide sequence of the PCR amplicons is closely related with the coat protein gene of piscine nodaviruses, particularly redspotted grouper nervous necrosis virus (RGNNV). Although, it was not succeeded to isolate the virus, experimental infection with the brain homogenates of the affected fish in sevenband grouper (Epinephelus septemfasciatus), which is highly susceptible to RGNNV, produced neuro- logical abnormality followed by mortality. These results suggest that the mortality observed in golden grey mullet in the Caspian Sea might have been associated with piscine nodavirus infection.

Three experiments of 28 days duration were conducted in three size groups (

Since the quality of sperm is affected by water industrial or agriculture pollution, sperm motility was measured as a sensitive and accurate bioindicator of water quality. In this study, sperm motility was measured by a computer assisted sperm analysis after 24 hours exposure of sperm to different concentration of heavy metals) Cadmium and Zinc). The results show that the sperm motility was not related to the duration of exposure but to the metals concentration ration. The concentration of 1000ppm zinc or 2000ppm Cadmium could have adverse effect on sperm motility.

In conformity with programming to harvest from virgin resources of Myctophids (Benthosema pterotum) in the Oman Sea (Iranian waters), a series of research cruises and trial fishings were carried out from 1992 to 1998. Assessment of B. pterotum stocks was carried out using the data obtained from a series of seven cruises conducted by R/V Ferdows1 in the Iranian waters using modern scientific echo sounder of EK500 system in 1993-94, with complementary monitoring surveys in the following years. The biomass estimates ranged from 1 to 4 million tones with an average of 2.3 million tons. A number of fishing operations using mid-water trawls were also performed in 1994-1998 using the same vessel. Distribution of B. pterotum was found to be all around the Oman Sea. The dense schools of this species were found in the northwest areas of the Iranian waters. Also the F/V Jahad Fanoos was applied during 1994-95 to do some trial fishings and its maximum catch was 50 t /h.