Iranian Journal of Ichthyology
Volume:8 Issue: 3, Sep 2021

In the present study, population characteristics of Katsuwonus pelamis were evaluated by sampling fish at five fish landing sites in the northern Oman Sea (Iran) including Beris, Ramin, Pozm, Konarak and Jask from March 2017 to March 2018. The biometric analysis was performed on more than eleven thousand fish. Growth and mortality indices were calculated including infinite length (L∞=88cm), growth coefficient (K=0.3 (yr-1 )), growth performance index (Ф=4.19), natural mortality (M= 0.58(yr-1 )), fishing mortality (F=0.3 (yr-1 )), total mortality (Z=0.88±0.1 (yr-1 )) and exploitation coefficient (E = 0.34 (yr-1 )) as well as length time at time zero (-0.41). Relative production per recruitment, relative biomass per recruitment and exploitation rate of K. pelamis were Y'/Rp=0.01, B' /Rp=0.4 and U=0.22, respectively. The present study showed that the K. pelamis had desirable stock conditions and fish stocks have not reached 'overfished' status. The Pobj value is 1<Pobj˂2, and Popt and Pmega>0, the fishery show considered medium desirable. According to the terms and situation mentioned conditions assessed, and considering the sustainable fishing requirements, it is possible to increase the catch of this species in the south of the country.

In this study the sagitta morphology of seven species of Gobiidae including three species of the genera Neogobius and four Ponticola, inhabiting the southern part of the Caspian Sea was described and analysed. The goal was to investigate the usefulness and efficiency of sagitta for species identification. The morphological analysis was based on four shape indices, roundness (4S/πOL2 ), rectangularity (S/OL×OW), ellipticity (OL-OW/OL+OW), and aspect ratio (OL/OW). The results indicated that otolith morphology and morphometry can be used as diagnostic characters distinguishing the Caspian Sea gobies. While the overall shape of otoliths differentiated the genera, the differences in the shape of the dorsal rim and development of posterior dorsal and anterior ventral lobes were particularly important for inter-specific distinction. The discriminant analysis could separate the specimens of genus Ponticola and Neogobius with 61% and 82% classification successes, respectively, proves that otolith shape indices were a more efficient tool for discrimination of otoliths in Neogobius than Ponticola species. Cluster analysis based on otoliths shape indices showed two main clusters, one cluster contains Neogobius species with higher roundness values, possessed more rounded shaped otoliths and the other includes Ponticola species with spindle and elongated shaped otoliths, except P. bathybius, recognized P. bathybius and Neogobius melanostomus as more similar taxa. These results were consistent with the phylogeny of these species proposed by recent molecular studies and indicated that otolith characteristics are partly genetically encoded and therefore have phylogenetic signals. The current research revealed a high degree of morphological variability of otolith shape in different species and confirmed its usefulness in Gobiidae taxonomy and phylogeny.

First record of the Triplefin fish (Blenniiformes: Tripterygiidae), Helcogramma ellioti, is reported here based on six specimens collected from Chabahar, northern Gulf of Oman in February 2019. Identification was confirmed based on a series of morphological characters including, a minute supraorbital tentacle, 3-5 symphyseal mandibular pores, a numerous number of scales in lateral line (36-37) and a low number of total lateral scale rows (38-39). Specimens were found in coral reef areas at depths of 1-15 m of the Gulf of Oman in the Indo-Pacific region. Compared to the other members of Helcogramma, H. ellioti is regarded as a medium to large body size species (25.0-57.0mm SL). Although several species of triplefin fishes have been reported from the Persian Gulf, but, it is the first record from Tripterygiidae for the Iranian waters of the Gulf of Oman

During surveys of the Hadhramout coast, the Gulf of Aden, five fish species were recorded. Review of all previous studies and publications show that these species from different families were not previously reported in the Gulf. The species identified include Lepidocybium flavobrunneum (Gempylidae), Muraenesox cinereus (Muraenesocidae), Conger macrocephalus (Congridae), Histiopterus typus (Pentacerotidae) and Brotula multibarbata (Ophidiidae). This paper describes the detailed characteristics of each species

This study was conducted to assess the species composition, abundance and metrological data influencing fish species diversity based on catch data from landing site of the Sunye Lake. The finding represented that 25 species belonging to 13 families. Cypriniformes was highest composition in community. Both diversity and evenness were low and only a few species were dominated. Low diversity value (H) and highest dominance index values (1-D) were associated with lower diversity estimates for this community. Major dominant species Oreochromis niloticus was the most widely distributed species with a 100% occurrence occurring in the lake. Highest occurrence was recorded during summer. Seasonal abundance of commonly captured species were O. niloticus, Amblypharyngodon atkinsonii, Puntius sophore, Parambassis ranga and Notopterus notopterus. In this community O. niloticus was recorded in the late monsoon and winter whereas A. atkinsonii and P. sophore were recorded in greater abundance during the early monsoon and summer. Finding results indicated that no significant (P<0.05) difference in diversity pattern among the seasons. According to metrological data, we observed similar seasonal pattern trends during two years study. However, productivity was different and their percentage of contribution also differs from each other seasonally. Percent similarity indicated that winter and summer were most similar season in terms of species richness. Seasonal difference in relative abundance indicated that late monsoon and winter were most dissimilarity.

The present study was aimed to investigate sexual dimorphism in morphometric and meristic characters of three carangid species Carangoides ferdau, Carangoides malabaricus, and Gnathanodon speciosus from the Red Sea, Egypt. The basic statistics of the morphometric indices (relative to SL or HL) of the three carangid species considered sexual dimorphism in C. ferdau, C. malabaricus, and G. speciosus regarding some indices that are size-free and valid as a discriminating tool between males and females of the examined species. The type of size allometry of males and females of the three studied species was estimated according to the bivariate concept. No sexual dimorphism was observed in the meristics characters. Additional features should be investigated to determine sexual dimorphism to facilitate the identification for conservatory purposes and correct management.

An increased understanding of fisheries target species population dynamics is a key requirement for successful management. Age, growth, and mortality of Indian mackerel, Rastrelliger kanagurta were estimated based on samples collected from commercial purse seine fishery in the Egyptian Red Sea between October 2019 and September 2020. The age estimates were based on two readers to increase the accuracy of results. The age estimates, in the period of study, were observed at a maximum age for both sexes at 4 years old and the most sampled occurrences in the second years (2 years old). The von Bertalanffy growth function was estimated for males at L∞= 343.83-0.447 (t+0.474); for females at L∞= 367.37-0.357 (t+0.767) and combined at L∞= 353.78-0.406 (t+0.595) . The mortality rate was determined at 1.35, 1.32 and 1.37 year-1 and exploitation ratio at 0.417, 0.511 and 0.492 year-1 for males, females and combined receptively. The length at first maturity (L50) was estimated at 206.9, 208.26 and 207.48mm for males, females and combined receptively. The updated estimates of these biological parameters, by this study, indicate that R. kanagurta population is more vulnerable to fisheries exploitation than before.

Introduction of species outside their native distribution ranges, followed by population establishment and becoming an invasive element, has been a common task and a controversial issue in the last century. The topmouth gudgeon Pseudorasbora parva is a gobionid fish native to southeast Asia, with a high dispersion potential, which succeeded in spreading out in many countries of Eurasia and north Africa including Iran during the almost 50 years. In this study, we are addressing the following research questions: (1) how do fish morphology differ in different water bodies by applying traditional, and geometric morphometric methods? (2) does morphology of P. parva show previous molecular-phylogenetic research based on mtDNA? Results revealed that traditional morphometric characters do not demonstrate a high phenotypic variation among 20 populations of P. parva collected from nine basins/river drainages. The cluster analysis of Euclidean distances among groups of P. parva populations (nine basins/river drainages) revealed segregation of three populations (Harirood, Esfahan and Mashkid basins). Based on the genetic background and colonisation history of P. parva using the mitochondrial DNA control region (806 bp) and a cytochrome c oxidase subunit I barcode database (615 bp), presence of three matrilineal haplotypes belonging to two lineages was confirmed: (1) a widespread lineage with a common haplotype found throughout the country and one exclusive haplotype confined to the Mashkid basin, whose origin can be traced back to a single introduction of a small number of propagules from Japan, and (2) a Chinese lineage represented by a single haplotype found in the Shafarood River of the Caspian Sea basin but also translocated to central Iran. This genetic clustering is somehow in correspondence to the dendrogram derived from the cluster analysis of geometric-morphometrics of P. parva populations and might be due to habitat-induced or genetically induced changes (e.g., fish origin), or it may arise due to the combination of both.