Iranian Journal of Ichthyology
Volume:7 Issue: 3, Sep 2020

The purpose of this study was to develop a framework to investigate the catch trend and estimation of the optimized catch limit of the Largehead hairtail, Trichiurus lepturus, stock by collecting catch data in the Iranian part of Persian Gulf and Oman Sea. In this research, catch data was collected for 20 years (1997-2018) and the optimized catch limit was estimated using data-limited approach and R Software. The average catch (Ct) for this period was 11550 tonnes (95% confidence interval 11500-11599 tonnes) and it has significantly increased over the past two decades (R=0.68, P<0.05). The intrinsic growth rate (r), carrying capacity (K), maximum sustainable yield (MSY), biomass of maximum sustainable yield (Bmsy), current biomass (B), fishing mortality of maximum sustainable yield (Fmsy) and present fishing mortality (F) were obtained by Catch-maximum sustainable yield (CMSY) models. The results showed that stock of the Largehead hairtail is suffering from over fishing and thereby, reduction of the fishing mortality and exploitation rate and bring back them to the MSY level are essential to save the stock.

The geographic isolation and specific character of local habitat could cause variation of morphological characteristics among Cork fish population in different locations. The plasticity of cork fish to adapt to the environment factors possibly has an impact on the different of specific morphological on fish population at different habitat. This study was conducted to investigate the traditional morphometric measurement and truss network differentiation of cork fish populations in different locations at Sumatra Island. Total of 394 cork fish specimens (consisting of 198 males and 196 females) were collected from nine different areas of rivers, swamp and lakes. The samples were analysed based on 14 morphometric (M) and 21 Truss Network Measurement (TNM) characters to find out the significant correlation of the fish on each area sampling. The transformed datasets were proceeded to multivariate testing using Discriminant Function Analysis (DFA) and Cluster Analysis (CA). The results showed that cork fish had 20 distinguishing predominant characters in the head and back of the body. Based on cluster analysis, those fishes were divided into 4 groups depending on geographical isolation except one floodplain population that differs from the other population groups. We revealed that phenotypic dimorphism for female cork fish had a dominant size compared to males in head region and tail fin region. Cork fish in the lake had a dominant body height size compared to rivers and flooded swamps.

Sox9 is a protein-coding gene that plays a critical role during organogenesis and regulation of the male gonad development among vertebrates. Knowledge about the expression of Sox9 during larval development can help to complete the lack of the information on its possible function in sturgeon fishes. Due to the importance of the Persian sturgeon as a valuable candidate species for aquaculture and the importance of Sox9 gene in vertebrate evolution, in this study, Sox9 cDNA was characterized and the expression pattern during various ontogeny stages (unfertilized egg to 210 days post hatching - dph) and among ten different tissues (gill, pyloric, spleen, gonad, kidney, intestine, heart, skin, liver, muscle) was analyzed using RT-PCR method. Results indicated that Sox9 mRNA was not detect in unfertilized and fertilized egg. However, first expression was measured at 1 dph then Sox9 mRNAs decreased in a gradual manner during the 1 to 50 dph and declined to minimal level at 210 dph (P<0.05). Also, Sox9 mRNA was present in most tissues with the highest expression in the gill and pyloric, weakly expression in the liver and gonad and no expression in the muscle. Our findings suggest that Sox9 was not applicable in sex determination in early developmental stages and probably it can be implicated in other developmental activities such as chondrogenesis.

Barilius vagra is an important freshwater fish found in the streams of hilly region of the Indian Himalaya consumed by local inhabitants. Genetic characterization of B. vagra was done using COI gene sequences of mitochondrial DNA (mt DNA). The COI gene of 18 individuals collected from two geographically isolated river basins of Indian Himalaya was sequenced. 18 sequences having more than 640 base pairs of B. vagra revealed the nucleotide diversity to be 0.00169 and 0.00330, respectively, from the Alaknanda and Chenab River basins. The haplotype gene diversity was found to be 0.806 and 0.833 for B. vagra from the two river basins, respectively. The maximum likelihood phylogenetic tree revealed the presence of two separate genetic stocks of B. vagra from the Alaknanda and Chenab River basins. The results of the present study suggested that the geographically isolated populations of B. vagra have developed significant divergence amidst the basins. This information would be useful for planning effective management strategies for conservation of hill trouts.

The present study was conducted in 2012 to evaluate the seasonal fluctuations of plasma sex steroid hormones including testosterone (T), 17β-estradiol (E2) and progesterone (P) in Indian major carp brooders in Khuzestan Province, Iran. The results revealed that T levels in females of Labeo catla and Lobeo rohita did not change during a year; however, females of Cirrhinus mrigala had the highest plasma T level (0.57±0.16ng mL-1 ) during maturing stage in spring compared to the other seasons. In males, bimodal peaks of plasma T was noticed in L. catla (summer and winter) and L. rohita (spring and winter), but in C. mrigala the highest T level (0.19±0.04ng mL-1 ) was observed in winter. Plasma E2 levels surged during autumn and winter in females of C. mrigala. The lowest level of plasma E2 was noticed in summer in females of L. rohita, but it did not affect in males. The highest level in female brooders of L. catla and C. mrigala was noticed in winter and spring, respectively; whereas, in female brooders of L. rohita, the highest (0.86±0.1ng mL-1 ) and the lowest (0.16±0.04ng mL-1 ) plasma P levels were observed in autumn and summer, respectively. These results indicating high temperatures in Khuzestan Province could be truncated reproductive development in Indian carps.

In the present study, different stages of the ontogeny of the liver and pancreas in the Acipenser persicus were illustrated from hatching until 36 days post hatching (dph) by histological techniques. The histological sections (sagittal plane) were made by a microtome at a thickness of 5 µm and stained with Hematoxylin and Eosin, Periodic Acid-Schiff and Masson's trichrome. Based on the results, in 2 dph, liver stroma was formed and stellate hepatocytes included numerous vacuoles with nuclei situated parametrically. On 10 dph, the pancreas was observed between the liver and anterior part of the intestine for the first time. Exocrine pancreatic cells were organized in acini. At 18 dph, the central veins and hepatic sinusoids were remarkably apparent in the middle of the liver parenchyma. The pancreas grew as a basophilic organ and it was situated in the posterior intestine on the 22-dph, bile duct, portal vein and hepatic artery was acquiring their structure in connective tissue. On day 36, the liver was characterized by an enlarged and organized form. Formation of the hepatopancreatic tissue is completed within 16 to 36 days after hatching.

This study was conducted to investigate the morphological variation between seven populations of Oxynoemacheilus seyhanensis inhabiting three basins of Turkish inland waters. For this purpose, a total of 71 specimens were collected from Yildizeli, Taşköprü, Suşehri rivers (Kizilirmak basin), Büyükpotuklu, Pinarbaşi and Örenşehir rivers (Seyhan basin) and Akdağmadeni River (Yesilirmak basin). A total of 31 morphometric characteristics were measured. After standardization, data were analyzed using one-way ANOVA and Duncan, Kruskal-Wallis tests, principal component analysis (PCA), canonical variate analysis (CVA), non-parametric MANOVA and cluster analysis. The results showed significant differences in 26 traits between the studied populations of O. seyhanensis (P<0.05) revealing a high morphological flexibility of this deep-bodied species.

The diet and feeding ecology of cyprinid fish species Devario aequipinnatus, Rasbora daniconius, Puntius bimaculatus, Dawkinsia filamentosa and Garra mullya were studied exploring the dietary breadth and overlaps of the species in the Chittar River, Southern Western Ghats, India. The diets of D. aequipinnatus, and R. daniconius were specialized animal matter and terrestrial arthropods whereas P. bimaculatus and D. filamentosa consumed large composition of algae and small portion of detritus respectively. Meanwhile the smaller portion of animal matter was present in the gut of P. bimaculatus while G. mullya fed on only algae and detritus with higher amount of plant matter. Levin’s index diet breadths analyses showed major overlaps between R. Daniconius and D. aequipinnatus and between G. mullya and P. bimaculatus in all the seasons. In the confluence site, generalist such as D. filamentosa and P. bimaculatus had an overlap with R. daniconius in four taxa food items and animal matter category. D. aequipinnatus and R. daniconius fall in specialist group. This D. aequipinnatus and R. daniconius species fed mainly on terrestrial arthropods from the surface. Garra mullya get a narrow feeding range in all seasons. Among co-existing species, diet overlaps were noticeably low in all seasons. Among the five cyprinids species high diet breath value and highest food overlapping was observed in the intermediate and south-west monsoon seasons. These results suggest that the diets of the fish assemblages had a distinct similarity and dissimilarity between and within surface and bottom feeding guilds. The results revealed a co-existence of five cyprinid fishes in the study area of Chittar River where a highly structured stream assemblage was observed.