Liza Saliens Research Articles

Köyceğiz-Dalyan Lagün Ekosistemi Kefal Populasyonlarının Büyüme Performans İndeksleri

As it is common in tropical and temperate zones, mullet species constitute the most important fish species caught along the coast and estuaries of Turkey. In terms of ecology, tourism and and fish productivity (52 kg/ha), Koycegiz-Dalyan Lagoon Ecosystem (KDLES) is the most important lagoon, with a 5500 ha surface area, is the Mediterranean Coast of Turkey. In the dalyan (barrier fish trap) systems; approximately 225 tons (80-405 tons) of mullets are caught to obtain 5 tons of dried fish eggs per year. Seventy percent of fish production in the lagoon is composed of mullets. The mullet samples were collected monthly between October 1992 and September 1994 from eight stations (one of them is a marine station) by trammel nets. The ages were determined using by scales anda ge composition varied form 0 to 6 ages. Species composition of 1159 sampled individuals were proportionally determined as Mugil cephalus 45%, Liza aurata 35%, Liza saliens 14%, Liza ramada 12%, Chelon labrasus 6%. The growth performance indices calculated from von Bertalanffy growth parameters using by all individuals for the M. cephalus, L. aurata, L. saliens, L. ramada and C. labrasus were determined as 2.957, 2.866, 2.692 and 2.719, respectively. The highest growth performance index was calculated for M. cephalus. The growth performance indeces of mullet species in Köyceğiz-Dalyan Lagoon Ecosystem were found around the world averages.

Population Dynamics of Mullets Mugil cephalus, Liza aurata and Liza saliens in Tendra and Yagorlyk Bays and Adjacent Sections of the Black Sea

Population Dynamics of Mullets Mugil cephalus, Liza aurata and Liza saliens in Tendra and Yagorlyk Bays and Adjacent Sections of the Black Sea

Fshr: a fish sex-determining locus shows variable incomplete penetrance across flathead grey mullet populations.

SummaryWhole-genome sequencing data were produced from a single flathead grey mullet female and assembled into a draft genome sequence, whereas publicly available sequence data were used to obtain a male draft sequence. Two pools, each consisting of 60 unrelated individuals, respectively, of male and female fish were analyzed using Pool-Sequencing. Mapping and analysis of Pool-Seq data against the draft genome(s) revealed >30 loci potentially associated with sex, the most promising locus of which, encoding the follicle-stimulating hormone receptor (fshr) and harboring two missense variants, was genotyped on 245 fish from four Mediterranean populations. Genotype data showed that fshr represents a previously unknown sex-determining locus, although the incomplete association pattern between fshr genotype and sex-phenotype, the variability of such pattern across different populations, and the presence of other candidate loci reveal that a greater complexity underlies sex determination in the flathead grey mullet.

Identification of larval stages of fish in southeastern coastal waters of the Caspian Sea- Golestan Province

This study was carried out to develop a practical guide for identifying species of fish larvae in coastal waters of Caspian Sea-Golestan Province. A total of 18 sample sites in the Caspian Sea and 6 sampling sites in the Gorgan Bay was sampled monthly from March to September 2015 with a Bongo net (diameter, 46cm; mesh size, 330 µm). Most of the fish larvae belonged to postflexion and transitional stages. Morphological and meristic measurements were made. Fish larvae included Atherina boyeri, Rutilus rutilus, Rutilus firisii kutum, Cyprinus carpio, Liza saliens, Liza aurata and Gambusia holbrooki, representing 5 genera in 4 families. Results showed Cyprinus sp. and Rutilus sp. separated based on pigments patterns on the body while R. rutilus and R. frisii kutum were discerned by the number of pre-anal myomers. Liza spp. could be differentiated by different pigments patterns and some morphometric characters including eye diameter, body depth, and head length. The results of this study revealed that in contrast to the current perception, the analysis of the morphometric variation of Liza sp., Rutilus sp., and Cyprinus carpio fry could be used for their discrimination.

Length-Weight, Length-Length Relationships and Condition Factor of commercial grey mullet species from Köyceğiz Lagoon in Turkey

The relationships between length weight, length length parameters and condition factor were given for 4 grey mullet species that caught in Köyceğiz Lagoon area between January 2017 and December 2017. Total length and weight were recorded and they ranged from 6.2-39.3 cm and 2.34-508.38 g for Liza aurata, 8.9-47.6 cm and 8.61-1006.5 g for Mugil cephalus, 5.0-37.7 cm and 1.62-478.90 g for Chelon labrosus and 3.8-35.2 cm and 0.52-462.88 g for Liza saliens. The length-weight relationships were determined for L. aurata, M. cephalus, C. labrosus and L. saliens as W=0.0087L2.96, W=0.0106L2.95, W=0.0073L3.065 andW=0.0067L3.045 respectively. All the fish species showed isometric growth (b=3). There were strong correlations between total length, fork length and standard length of 4 fish species (P<0.001). Also the condition factor values significantly (P<0.001) range between 0.56-1.30 for L. aurata, 0.66-1.22 for M. cephalus, 0.64-1.30 for C. labrosus, 0.57-1.06 for L. saliens.

Assessing the health of marine and lacustrine wetland using measurement of heavy metals in fish species: Case study from two Iranian international wetland (Gomishan and Zarivar)

Wetlands are highly sensitive to pollution effects as they are usually low lands in comparison to the surroundings. Consequently, pollution with heavy metals in the wetlands ecosystems may have changed the ecosystem's biogeochemistry. Gomishan and Zarivar wetlands are regarded as two of the most important wetland regions in south eastern corner of Caspian Sea and in Western Iran respectively. We report the results from a detailed research based on two metals (Pb and Cd) measured in muscle of two fish species (Cyprinus carpio and Liza saliens) from Gomishan and Zarivar wetlands. Twenty three leaping mullet (Liza saliens) fish samples (from the 9 stations) and twenty common carp (Cyprinus carpio) were collected in year 2013 from Gomishan international wetland and Zarivar wetland respectively. Using a hot-block digester, the muscle samples were digested with a combination of perchloric acid (HCLO4) and nitric acid (HNO3) and then examined by atomic absorption spectrophotometry. The ranges of the concentrations of metals in the edible muscle tissues were: Pb 0.14–0.57 μg/g; Cd 0.34–0.49 μg/g; in common carp and Pb 0.00075–0.03 μg/g; Cd; 0.08–0.025 μg/g in leaping mullet. Pb and Cd concentrations between both fish species were statistically significant (insert the p value). There was no statistically significant correlation between the metal concentration of the muscles and the fish weight for both species. The concentrations of heavy metals in muscle of examined both fish species were below the permissible levels and should not pose health problems for human consumption. Periodic monitoring of these metals in both fishes and water to ensure safety is recommended.

Health risk assessment of selected heavy metals in some edible fishes from Gorgan Bay, Iran

The objective of this study was to determine the distribution of selected metal concentrations (Cd, Pb, Cr and Fe) in the muscles of five fish species (Sander lucioperca, Liza auratus, Alosa caspia, Cyprinus carpio and Liza saliens) from Gorgan Bay the south-eastern Caspian Sea, in order to assess health risk to the human via fish consumption by graphite furnace atomic absorption spectrophotometry. Potential health risk assessments based on estimated daily intake (EDI) values and target hazard quotient (THQ) indicated that the intakes of metals by consuming these fish species do not result in an appreciable hazard risk for the human body. The hazard index (HI) calculated was lower than 1 for all the species. However, the results indicate that the concentrations high value of Pb (in the muscle of L. auratus) and Fe for all fish is alarming and do present an appreciable hazard risk for human health.

Histopathological and ultrastructural assessment of two mugilid species infected with myxozoans and helminths.

The histopathology and ultrastructure of the intestine of mullets, Liza ramada and Liza saliens, from Comacchio lagoons (northern Italy) naturally infected with myxozoans and helminths were investigated and described. Sixty-two (80.5%) of 77 mullets harboured one or more of the following parasites species: Myxobolus mugchelo (Myxozoa), Neoechinorhynchus agilis (Acanthocephala), Haplosplanchnus pachysomus and Dicrogaster contractus (Digenea). Co-occurrence of helminths with myxozoans was common. The main damage caused by digeneans was destruction of the mucosal epithelium of the villi, necrosis and degeneration of intestinal epithelial cells. More severe intestinal damage was caused by acanthocephalans which reach the submucosa layer with their proboscis. At the site of helminths infection, several mast cells (MCs), rodlet cells (RCs), mucous cells and few neutrophils and macrophages were observed in the epithelium. RCs and mucous cells exhibited discharge activity in close vicinity to the worm's tegument. M.mugchelo conspicuous plasmodia were encysted mainly in muscle and submucosa layers of the intestine. Indeed, spores of M.mugchelo were documented within the epithelial cells of host intestine and in proximity to MCs. Degranulation of the MCs near the myxozoans was very frequent.

Characteristic of feeding of mullet fishes in Shabolatsky estuary

The worsening of the ecological situation in the last years resulted in the decrease of biodiversity and general fish productivity of the saltish-water Shabolatsky estuary, placed in Danube-Dniester interfluves. It doesn’t allow to use it effectively for the traditional pasturable cultivation of mullet fish.The aim of the work was to study the features of feeding, food relations and growth of indigenous species of mullet (stripped mullet, leaping grey mullet, golden mullet) and soiuy mullet acclimater at the pasturable cultivation under conditions of Shabolatsky estuary. The collection of ichthyological material was realized in 2012-2014. At the study of mullet feeding were used standard methods that allowed to assess season changes of qualitative and quantitative parameters of feeding and food relations of mullet: stripped mullet - Mugil cephalus, golden mullet – Liza aurata, leaping grey mullet – Liza saliens, soiuy mullet – Liza haematocheilus.For the first time there was given the qualitative characteristics of feeding and food relations of different types of mullet in season and age aspects. It was demonstrated, that leaping grey mullet and golden mullet of all age groups in all seasons of a year prefer animal food; stripped mullet and soiuy mullet – detritus and vegetable food. The most similarity was inherent to the qualitative compositions of rations of yearlings of all mullet species in the spring period (feeding similarity index FSI – 63,0-76,5). In summer the food composition changed (decreased for animal plankton and increased for zoobenthos). The tension of food relations decreased (FSI – 49,8-75,0). In autumn the most similarity of the food character was typical for second-year golden mullet and leaping grey mullet on the one side and second-year and third-year stripped mullet and soiuy mullet (up to 75-89% of detritus and vegetable food) on the other one. At the same time golden mullet and leaping grey mullet essentially differed from stripped mullet and soiuy mullet by the food character. The decrease of zooplankton and zoobenthos production, noticed in Shabolatsky estuary in last years resulted in the decrease of the growth speed of leaping grey mullet and golden mullet. At the same time essential reserves of detritus of vegetable food provide the intensive growth of striped mullet and soiuy mullet.In the existent situation it is expedient to use striped mullet and soiuy mullet detritophages as main objects of the pasturable mullet cultivation to provide the maximal fish productivity of the water body.

Evolutionary morphology in shape and size of haptoral anchors in 14 Ligophorus spp. (Monogenea: Dactylogyridae).

The search for phylogenetic signal in morphological traits using geometric morphometrics represents a powerful approach to estimate the relative weights of convergence and shared evolutionary history in shaping organismal form. We assessed phylogenetic signal in the form of ventral and dorsal haptoral anchors of 14 species of Ligophorus occurring on grey mullets (Osteichthyes: Mugilidae) from the Mediterranean, the Black Sea and the Sea of Azov. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors and two different tests were applied to establish whether the spatial positions in the morphospace were dictated by chance. Overall significant phylogenetic signal was found in the data. Allometric effects on anchor shape were moderate or non-significant in the case of evolutionary allometry. Relatively phylogenetically distant species occurring on the same host differed markedly in anchor morphology indicating little influence of host species on anchor form. Our results suggest that common descent and shared evolutionary history play a major role in determining the shape and, to a lesser degree in the size of haptoral anchors in Ligophorus spp. The present approach allowed tracing paths of morphological evolution in anchor shape. Species with narrow anchors and long shafts were associated predominately with Liza saliens. This morphology was considered to be ancestral relative to anchors of species occurring on Liza haematocheila and M. cephalus possessing shorter shafts and longer roots. Evidence for phylogenetic signal was more compelling for the ventral anchors, than for the dorsal ones, which could reflect different functional roles in attachment to the gills. Although phylogeny and homoplasy may act differently in other monogeneans, the present study delivers a common framework to address effectively the relationships among morphology, phylogeny and other traits, such as host specificity or niche occupancy.

Genetic diversity of sharpnose mullet Liza saliens introduced in southern Caspian Sea in comparison with one native Aegean Sea population

Sharpnose mullet, Liza saliens (Risso, 1810) is one of the valuable species in Caspian shoreline and it was first introduced to Caspian Sea from Black Sea between 1930 and 1934. In the present study, we used six microsatellite markers to obtain genetic information for L. saliens from four localities of southern Caspian Sea and for one native population from Greece coastline (northern Aegean Sea). Results showed lower number of alleles (Na = 5.7–6) and higher observed heterozygosity (Ho = 0.74–0.83) in Caspian Sea samples, related to the native Aegean population (Na = 8, Ho = 0.68). Significant deviations from Hardy-Weinberg expectations were detected in 19 out of 28 tests. Low genetic differentiation (provided Fst values) among samples was detected, but Behshahr sample was significantly differentiated from all the others. The UPGMA tree revealed three major clusters: the Behshahr sample and Greek population were clustered in two different clades, and the remaining three samples formed another cluster. The low genetic variation and spatial differentiation among Caspian Sea samples may be justified by the recent establishment.

New Fisheries-related data from the Mediterranean Sea (November, 2016)

In this fourth Collective Article, with fisheries-related data from the Mediterranean, we present weight-length relationships for eight deep-sea fish species (Brama brama, Conger conger, Etmopterus spinax, Molva macrophthalma, Mora moro, Pagellus bogaraveo, Phycis blennoides) from the Eastern Ionian Sea; Scyliorhinus canicula from various locations in the Mediterranean Sea and weight-length relationships and condition factor of five Mugilidae species (Liza aurata, Liza saliens, Liza ramada, Mugil cephalus, Chelon labrosus) from a Mediterranean lagoon in the Ionian Sea. Moreover, we present otolith weight, fish length and otolith length relationships of the red mullet (Mullus barbatus) in the Aegean and Ionian Sea and otolith weight relationships in European hake (Merluccius merluccius) from the Greek Seas.

English

The examination of 415 specimen belonging to twelve species of Teleostean fish and 339 specimen belonging to seven species of Chondrichthyan fish collected from the Tunisian coasts, it enabled us to identify 10 species of parasitic copepods: Lernaeopoda galei, Lernaeocera lusci, Neobrachiella merluccii, Hatschekia mulli, Caligus elongatus, Caligus pageti, Neobrachiella mugilis, Clavellotis fallax, Clavelissa pagri and Clavelissa scombri. The distribution of copepods identified, varies from one host species to another. Merluccius merluccius and Liza saliens present the important number of copepods species. The copepod Hatschekia mulli is the most abundant. The presence of Lernaeopoda galei on Scyliorhinus canicula, Mustelus mustelus and Mustelus punctalatus was reported for the first time in the southern banks of the Mediterranean. Key words: Copepods, Teleost fish, Chondrichthyan fish, Tunisian coasts, parasitic indices.

Molecular and morphological characterisation of two species of the genus Ellipsomyxa Køie, 2003 (Ceratomyxidae) from the gall-bladder of Liza saliens (Risso) off Tunisian coasts of the Mediterranean.

During examination of some species of the family Mugilidae, two coelozoic myxozoans were observed in the gall-bladder of the leaping mullet, Liza saliens (Risso). Spore morphology allowed us to allocate them to the genus Ellipsomyxa Køie, 2003, one of which is described here as new. Ellipsomyxa kalthoumi n. sp. was observed forming globular pseudoplasmodia and free spores floating in the bile. Mature spores are ellipsoidal, measuring 13-21 × 10-15 (17.2 × 13.2) µm and possessing two equal spherical polar capsules, 5-6 (5.5) µm in diameter, opening subterminally in opposite directions, with nine polar filament coils. Morphological data and molecular analysis of the small subunit rDNA sequences helped identify this parasite as a new species of Elliposmyxa. The second species identified as E. mugilis (Sitjà-Bobadilla & Alvarez-Pellitero, 1993) has oval spores with rounded ends, measuring 10-11 × 7-9 (10.5 × 8.0) µm and possessing two polar subspherical capsules, 2.7-3.0 (2.8) µm in diameter, opening subterminally in opposite directions. Spore morphometry and molecular study of the small subunit (SSU) of the rRNA gene identified this species as E. mugilis described from the same host in the Western Mediterranean off Spain. Phylogenetic analysis revealed Elliposmyxa as a monophyletic clade and showed that E. mugilis, E. syngnathi Køie & Karlsbakk, 2009, E. adlardi Whipps & Font, 2012 and E. gobii Køie, 2003 group in a subclade containing the Tunisian isolate of E. mugilis whereas E. kalthoumi n. sp. appears in a second subclade together with four Australian species, E. maniliensis Heiniger & Adlard, 2014, E. apogoni Heiniger & Adlard, 2014, E. nigropunctatis Heiniger & Adlard, 2014 and E. arothroni Heiniger & Adlard, 2014.

Molecular characterization and morphological aspects of Myxobolus parvus (Myxozoa) from Liza saliens (Mugilidae) off the Turkish Black Sea coasts.

Members of the phylum Myxozoa are among the most cosmopolitan parasites of fish, and the genus Myxobolus is the largest within the class Myxosporea in freshwater and marine environment from all over the world. Myxobolus parvus has been reported from mainly mugilid fishes from different localities including the Black Sea. Leaping mullet Liza saliens collected by fishermen off Sinop coasts of the Black Sea in the period between September 2014 and December 2015 was investigated for myxosporean parasites using conventional methods. M. parvus Schulman, 1962 was the only Myxobolus species identified and it was found in the gills, gall bladder, kidney tubules, and inside several cysts located on the lower jaw of examined fish in the present study. Morphometric data and all details of parasitic infection were determined and presented in tables and illustrated in figures. Molecular characterization was also conducted to reveal its position within Myxosporea. Two M. parvus samples from gills and kidney showed the same haplotype and appeared in the same sub-lineage with marine Myxobolus species. The closest haplotypes to M. parvus were Triactinomyxon sp. and Endocapsa sp. which are the actinosporeans forms of unknown myxozoan species. These data are the first in molecular characterization of M. parvus, its occurrence in lower jaw of leaping mullet along with its infection prevalence values off the Turkish Black Sea coasts.

RETRACTED: Isolation and confirmation of viral nervous necrosis (VNN) disease in golden grey mullet (Liza aurata) and leaping mullet (Liza saliens) in the Iranian waters of the Caspian Sea

The present study was conducted on 428 moribund mullet fish samples to isolate and identify the causative agent of a mysterious acute mortality which recently occurred in wild mullets in Iranian waters of Caspian Sea, suspected to be due to viral nervous necrosis (VNN) disease. Disease investigation was carried out employing various diagnostic procedures such as virology, bacteriology, parasitology, haematology, histopathology, IFAT, IHC and nested RT-PCR. Brain and eye samples of affected fishes were collected in sterile conditions and then kept at -80°C for cell culture isolation and nested RT-PCR detection of the causative agent. Other tissue samples were also collected and fixed for histopathology, IHC and EM examinations. CPE was observed in cell cultures at 6days after inoculation. Nine samples were found positive with virological assay. Nested RT-PCR, performed on suspected tissues and CPE positive samples, showed that about 21 tissue samples and all the CPE positive samples were positive for VNN virus (VNNV). IFAT was selected as a confirmatory method for detecting the presence of Betanodavirus antigen, cell culture isolation results and nested RT-PCR findings. Moreover, VNNV particles with 25-30nm in diameter were also visualized in the infected brain and retina. In pathogenicity studies, guppy fishes bathed in VNNV-infected tissue culture (10(-4) TCID50) showed clinical signs similar to naturally infected mullet after 15days post infection (dpi), with mortality rates reaching up to 100% at 30dpi. Affected organ samples as examined by cell culture isolation, IFAT, IHC and histopathology, revealed the presence of VNNV in the guppy fishes. In conclusion, it was confirmed that VNNV was the main causative agent for the disease outbreak in mullet fish in the Caspian Sea, and this is such first official report of VNN disease from Iran.

Epidemiological and molecular data on heterophyid trematode metacercariae found in the muscle of grey mullets (Osteichthyes: Mugilidae) from Sardinia (western Mediterranean Sea).

This study is a contribution to the molecular taxonomy and epidemiology of heterophyid (Trematoda: Heterophyidae) metacercariae found in the muscle of Mugilidae (Osteichthyes) from Sardinia (western Mediterranean Sea). Sixty specimens of mugilids (13 Chelon labrosus, 18 Liza aurata, 6 Liza ramada, 8 Liza saliens, 15 Mugil cephalus) were examined and 17,899 metacercariae isolated in 95% of the hosts. Four types of metacercariae were identified: Heterophyes sp. (n = 14,113), Heterophyes sp. -small (1225), Stictodora sp. (1606), and Ascocotyle (Phagicola) sp. (955). The experimental infection of a hamster with Heterophyes sp. metacercariae produced six adults identified as Heterophyes heterophyes and two as Heterophyes cf. nocens. The morphology of Heterophyes sp. -small metacercariae matched with that of Heterophyes dispar. The sequence analysis of the ITS2 and 28S portions of rDNA confirmed the morphological identification of metacercariae, showing four clusters. All adults grouped together with the Heterophyes sp. metacercariae, whereas adults of Heterophyes nocens from Korea clustered separately, showing that this species is distinguished from H. heterophyes, and suggesting caution in the exclusive use of the number of rodlets of the genital sucker to separate the two species. The presence of metacercariae was high in all hosts; the highest prevalence is of Heterophyes sp. (prevalence ≥78%; mean intensity ≥135 metacercariae/100g muscle), and the most heavily infected host is M. cephalus (prevalence = 100%; mean intensity = 841 metacercariae/100g muscle).

Haemato-biochemical disorders associated with nodavirus like-agent in adult leaping mullet Liza saliens (Risso, 1810) in the Caspian Sea.

Betanoda virus is an emerging problem in several marine fish species in various geographic areas all over the world. In recent years, mullets stock of the Caspian Sea decreased dramatically and a betanoda virus like-agent was introduced as the cause of mullet's mortality. The main objective of the present study is to compare hemato-biochemical parameters in healthy and infected sharpnose mullets (Liza saliens) to betanoda virus like-agent. The adult sharpnose mullets (34 clinically affected fish+34 apparently healthy fish) were captured from the southeast the Caspian Sea from 2012 to 2013. All of the captured fish were 4 or 5years old. The main clinical sings of infected fish were lethargy, severe abdominal distention, abnormal swimming and hyperinflation of swim bladder. The results showed that the weight and total length of infected fish were significantly lower than the healthy fish. The results of histopatological evaluation and indirect florescent antibody test were confirmed the presence of a betanoda virus-like agent in infected fish. The diseased fish were severely anemic (hypochromic macrocytic anemia) and had a serious haemopoietic disorders. The anemia associated with a sever leukopenia, a significant rise of neutrophils and immature neutrophils and a significant decries of lymphocytes percentage. Total protein, albumin and total immunoglobulin levels were significantly reduced in the serum of infected fish, while the activities of aspartate aminotransferase and alanine aminotransferase significantly increased when compared to the healthy fish. These results suggested that the feeding of the infected fish to betanoda virus like-agent were disturbed and it could be cause haemato-biochemical disorder and mortality of the fish in Iranian water of the Caspian Sea.

Scale Surface Microstructure and Scale Size in Three Mugilid Fishes (Teleostei, Mugilidae) of Iran from Three Different Habitats

A substantial number of species within mugilid family has been recorded from marine, brackish and freshwater bodies of Iran. Descriptions of these species have been based mainly on morphological and anatomical data; however, the characters related to the fish scales have not up to now been intensively studied and employed for the identification of the fish species. The objective of this study is to test whether (i) scale surface morphology and microstructure, and (ii) scale size can be used to discriminate species. To achieve these objectives, scales of three species of the genus Liza from three different habitats, Liza abu (freshwater, Maharlu basin), Liza klunzingeri (sea, Persian Gulf) and Liza saliens (brackish water, Caspian Sea) have been studied using SEM images, scale measurements, and uni and multivariate statistics. It is opined that scale surface morphology and microstructure may help in distinguishing the species. In addition, scale size and J-indices, represent a valuable tool for species separation, which corroborates earlier studies for the use of these indices in fish taxonomy.

Vacuolating encephalopathy and retinopathy associated with a nodavirus-like agent: a probable cause of mass mortality of wild Golden grey mullet (Liza aurata) and Sharpnose grey mullet (Liza saliens) in Iranian waters of the Caspian Sea.

Mullets are dominant fishes in the catch composition in the southern coasts of the Caspian Sea and after (Rutilus frisii kutum Kamensky, 1901) have a worthy role in production of marine proteins and incomings of north provinces of Iran. Mullets stocks decreased dramatically in recent decades in the Caspian Sea and catch amount reached from 6446 MT on 2002 to 2151 MT in 2012. Mysterious mortalities occurred in wild mullet (Liza auratu) and (Liza saliens) in Iranian waters of Caspian Sea in recent years. Regarding to investigation of causative agent of mentioned outbreak about 322 suspected samples were collected from coastal capture sites of Iranian north provinces in 2008 till 2011. Moribund fish revealed skin darkening, erratic swimming, belly-up at rest and high distension of swim bladder. Target tissues such as brain and eye were removed and then fixed for histopathology and TEM assay. Widespread and massive vacuolation were observed in brain, spinal cord, retina and optical nerve and intracytoplasmic vacuoles and virus particles in retina. So concerning to clinical signs, histopathological and TEM findings, it could be concluded that nodavirus-like agent could be probable cause of mass mortality of wild mullet in Iranian waters of the Caspian Sea.