Egyptian Mediterranean Waters Research Articles

Fistularia commersonii (Rüppell, 1838) (Piscès: Fistulariidae): Length-weight relationship and condition factors from the Egyptian Mediterranean waters (West Alexandria)

Fistularia commersonii (Rüppell, 1838) (Piscès: Fistulariidae): Length-weight relationship and condition factors from the Egyptian Mediterranean waters (West Alexandria)

Fistularia commersonii (Rüppell, 1838) (Piscès: Fistulariidae): Length-weight relationship and condition factors from the Egyptian Mediterranean waters (West Alexandria)

Fistularia commersonii (Rüppell, 1838) (Piscès: Fistulariidae): Length-weight relationship and condition factors from the Egyptian Mediterranean waters (West Alexandria)

Population Dynamics and Stock Assessment of Atlantic Horse Mackerel (Trachurus trachurus) Stocks in the Western Egyptian Mediterranean Waters

Population Dynamics and Stock Assessment of Atlantic Horse Mackerel (Trachurus trachurus) Stocks in the Western Egyptian Mediterranean Waters

First record of the epipelagic Cranocephalus scleroticus (Streets, 1878) (Amphipoda: Hyperiidea) in the Egyptian Mediterranean waters

This study aims to document the first occurrence of the epipelagic amphipod Cranocephalus scleroticus (Streets, 1878) in the Egyptian Mediterranean waters. During the winter of 2019, only one female specimen was collected by a zooplankton net from El-Dabaa sector on the western coast of Egypt. An investigation of systematic position and concise redescription, along with some structural photos, was conducted to confirm the identification. Habitat and distribution are also provided in the study. A new record, that has never been recorded before, is added to the list of species of the Egyptian Mediterranean fauna.

Length-weight relationship and well-being factors of 33 fish species caught by gillnets from the Egyptian Mediterranean waters off Alexandria

This study investigates the growth pattern of 33 fish species caught by gillnets from the Egyptian Mediterranean waters off Alexandria between 2018 and 2020. This is accomplished by studying the length-weight relationship (LWR), Fulton’s condition factor (kc), the allometric condition factor (ka), and the relative weight condition factor (kn). The b-values of the length-weight relationship of the studied species varied between 2.1382 and 3.6868 according to the results. Only Dentex macrophthalmus (b = 2.1382), Etrumeus golanii (b = 2.4197), and Trichiurus lepturus (b = 3.6868) exhibited different values than the expected range of 2.5 < b less than 3.5. The 95 % confidence interval (CI) and Bailey’s t-test of b-values were tested. In terms of growth pattern, the results showed 20 fish species with an isometric growth pattern, 10 fish species with negative allometric growth, and only 3 fish species with positive allometric growth. The study of Fulton’s condition factor (kc) assessed the differences between species to the differences in fish shape, and proposed that each fish family has its own range depending on the fish shape, and (kc > 1) is not necessarily a better condition for the fish. The study of the allometric condition factor (ka) assessed that the difference between ka and kc values influenced by the feeding intensity and the b-value. The values of the relative weight condition factor (kn) were within the range from 0.929 to 1.038, and 24 fish species reflected a good growth condition while the kn values for the remaining 9 species were less than 1.0. The obtained results add new data about specific species and provide updated data on the remaining species in the area of study. The obtained results can have useful effects on the stock assessment of fish species.

Some biological aspects and population status of the bogue, Boops boops (Linnaeus, 1758) (Teleostei: Sparidae) caught by gillnets from the Egyptian Mediterranean waters off Alexandria

Some biological aspects and population status of the bogue, Boops boops (Linnaeus, 1758) (Teleostei: Sparidae) caught by gillnets from the Egyptian Mediterranean waters off Alexandria

Some biological aspects and fisheries assessment of Diplodus vulgaris (Geoffrey Saint-Hilaire, 1817) (Teleostei: Sparidae) caught by gillnets (Egyptian Mediterranean waters, Alexandria)

This study was conducted to estimate some biological aspects and fisheries assessment of Diplodus vulgaris caught by gillnets during the period 2018–2020 from the Egyptian Mediterranean waters of Alexandria. From an overall of 1004 individuals of D. vulgaris (10.0 – 24.0 cm TL) examined, lengths from 13.0 to 17.0 cm were representing 82.67% of the total fish number. The length-weight relationships for total and gutted weights of the D. vulgaris were: Log W = −1.7144 + 2.9063 Log L (R2 = 0.9982) and Log W = −1.8508 + 2.9903 Log L (R2 = 0.9967), respectively. The condition factor (k) was found to be fluctuating between 1.268 and 1.534 with an average value of 1.395 ± 0.0597. The overall sex ratio (M: F) was 1.00: 0.63 and the chi-square test revealed highly significant difference (χ2 = 24.80; df = 1; P < 0.01). The spawning season of D. vulgaris was observed from December to February for both sexes. The gonadosomatic index (GSI) reached its highest value in December for both sexes. The age composition of the D. vulgaris catch was estimated to be four years and the first age dominated the population. The present von Bertalanffy growth parameters were calculated as follows: the coefficient of growth (K) = 0.128 yr.-1, the asymptotic length (L∞) = 37.06 cm, and the hypothetical age at zero size (to) = −2.773 yr.-1. The growth performance index (Ф') was: Ф'L = 2.24, and Ф'W = 1.00. The reproductive load (Lm/L∞) was low for males (0.39) and females (0.37). The ratio LmaxD/ LmD was 1.36 and 1.39 for males and females, respectively and it was found to be compatible with the Pauly's Gill-Oxygen Limitation Theory (GOLT). The total mortality coefficient (Z) was 1.79, the natural mortality (M) was 0.39 and fishing mortality (F) was 1.40. The M/K was 3.0615 and Lc/L∞ was 0.371. At the level of the current exploitation rate (Ecur = 0.78), the stock is considered highly exploited by gillnets fishery and only 9.34% of the stock biomass is protected. Fishery management for this wild stock is highly required.

Livoneca redmanii Leach, 1818 (Cymothoidae) a parasitic isopod infesting the gills of the European seabass, Dicentrarchus labrax (Linnaeus, 1758): morphological and molecular characterization study

BackgroundPrevalence, morphology, and molecular characteristics of isopodiosis in the European seabass, Dicentrarchus labrax, in Egypt were assessed using light and electron microscopy and polymerase chain reaction targeting the mitochondrial COI (cytochrome oxidase c) gene.ResultsAdult parasites were found mainly in the branchial cavity between gill arches and to a lesser extent in the buccal cavity. They were morphologically identified as the Cymothoidae Livoneca redmanii Leach, 1818 (Crustacea: Isopoda). Obviously, a 23% prevalence rate of isopods was reported in D. labrax from Egyptian Mediterranean waters. Destructive and degenerative necrotic alterations with complete sloughing of gill lamellae of the infested fish were observed. DNA sequencing of the mitochondrial COI gene confirmed the identification of the parasite which was deposited in the GenBank under accession numbers MW600099, MZ208984, and MZ208985. Furthermore, the phylogenetic analysis demonstrated that parasites emerged from a monophyletic clade closely affiliated with L. redmanii and were clearly distinguished from other isopod genospecies.ConclusionThe present investigation addresses L. redmanii infestation in D. labrax in Egypt and affirmed morphological properties via the scanning electron microscopy (SEM) and molecular characteristics of this isopod species. The drastic effects of this parasite on the infected fish were proven both clinically and histopathologically.

Dynamics of polychaete communities in the intertidal soft bottom of Alexandria coast, Egypt

The species composition and abundance of polychaetes in the soft bottom intertidal zone of Alexandria coast were studied bi-monthly from August 2018 to June 2019. This study identified 42 species, including five newly recorded species for the Egyptian Mediterranean waters, which could be introduced either from the Western Mediterranean, Atlantic waters, or the Indo-Pacific Region. Furthermore, species diversity and numerical abundance of polychaetes showed significant temporal and spatial variations, which appeared to be related to environmental variability in the study area. The statistical analyses showed significant variations in polychaete assemblages and discriminated to some extent between locations that are subjected to anthropogenic impact and less impacted locations. Tolerant species contributed mainly to the abundance of the polychaete assemblages of impacted sites, in contrast with sensitive polychaetes species, which contributed mainly to the assemblages of less impacted sampling sites.

First record of the Lessepsian Sammara Squirrelfish, Neoniphon sammara (Forsskål, 1775), in the Egyptian Mediterranean waters

This paper discusses the first record of the sammara squirrelfish, Neoniphon sammara in the Egyptian Mediterranean waters. On April 2020, 17 specimens of this species were recorded in the miscellaneous catch at the Mersa Matruh landing site on the Mediterranean Sea (31.33333° Ν, 27.216665° E), Egypt. The collected specimens represent the first record of N. sammara in the Egyptian Mediterranean waters. These specimens have a total length of 15.3 to 21.5 cm, fork length of 13.3 to 18.7 cm, standard length of 12.4 to 17.2 cm, and total weight of 45.3 to 125.1 g. The specimens’ morphometric measurements and meristic counts are described. These new findings increase the number of Lessepsian species from the Egyptian Mediterranean waters to 44 species.

Growth and mortality rates for management of the common smooth-hound shark, Mustelus mustelus in the Egyptian Mediterranean waters

Growth and mortality rates for management of the common smooth-hound shark, Mustelus mustelus in the Egyptian Mediterranean waters

The update of immigrant Red Sea fish of Egyptian Mediterranean waters during (2013-2021)

The update of immigrant Red Sea fish of Egyptian Mediterranean waters during (2013-2021)

The update of immigrant Red Sea fish of Egyptian Mediterranean waters during (2013-2021)

The update of immigrant Red Sea fish of Egyptian Mediterranean waters during (2013-2021)

First record of Pteroplatytrygon violacea (Bonaparte, 1832) with annotation of cartilaginous fishes by-catch by gill nets (Egyptian Mediterranean)

Five cartilaginous fish species were recognized and identified as by-catch species during studying the catch of gill nets operated in the coastal area of Alexandria City from the Egyptian Mediterranean Waters during the study periods from Feb. 2018 to June 2018 and from Dec. 2019 to Nov. 2020. The by-catch included the first record of Pteroplatytrygon violacea, the closely related species Dasyatis pastinaca and Dasyatis tortonesei, the rarely found species Rhinoptera marginata, and the blackchin guitarfish Glaucostegus cemiculus. Among these five species, four species are listed in the IUCN Red List; as least concern for P. violacea, data deficient for D. pastinaca in the Mediterranean Sea, near threatened for R. marginata, and critically endangered for G. cemiculus. Morphological characters and morphometric measurements were studied to provide identification of these species. The species have been dissected for more biological information.

First record of a swarm of Thalia democratica (Chordata: Tunicata) in the Egyptian Mediterranean coast

The current study is the first to document a vast swarm of the pelagic tunicate Thalia democratica inshore of the Egyptian Mediterranean waters. On the May 05, 2021, a swarm of the Salpida T. democratica was discovered inshore of the coast of Stanley. The swarm coincided with a red tide bloom in the research area. The documented species is given a brief redescription with illustrative photographs, taxonomic annotations, habitat notes, and distribution.

The update of immigrant Red Sea fish of Egyptian Mediterranean waters during (2013-2021)

Thirty nine immigrant fish species from the Red sea were observed in seven regions of Egyptian Mediterranean waters during 2013- 2021. These were divided according to their importance in the fish markets into economic species (18) and non-economic species (21). Port- Said region (North opening of Suez Canal) constituted high percentage of occurrence (49.1% of all species) followed by Alexandria (41.9%), Abu-Qir (5.2%) and Marsa Matruh (3.7%). Thirteen new species were recorded in the present review whereas fifteen fish species in the checklist given by Halim and Rizkalla (2011) were not encountered in the study area during the study period. Alepes djedaba and Siganus rivulatus were the most important economic species established in Port Said region, whereas Nemipterus randalli and Sargocentrum rubrum were the more dominant in Alexandria region, Also Nemipterus randalli was well established in Abu-Qir area while Upeneus pori was abundant in Marsa Matruh region.

Comparative taxonomical studies on the Egyptian Mediterranean octopuses (Octopoda: Cephalopoda)

Octopuses have gained considerable worldwide commercial importance. Hence, this study was conducted to differentiate between the Octopoda species in the Egyptian Mediterranean waters. The study extended from January 2019 to December of the same year. Octopus specimens were seasonally obtained from the fishing trawlers operating in the Egyptian Mediterranean waters from Sidi Abd El-Rahman, west of Alexandria to Rosetta in the east. The different organs were illustrated using a zoom stereoscopic WildM8 microscope provided with a special camera Lucida drawing tube and photographed by a Canon G7Xdigital camera. Four Egyptian Mediterranean octopus species were detected, among which Eledone moschata, Octopus vulgaris, Callistoctopus macropus, and Macrotritopus defilippii were identified. Whereas three of them: Octopus vulgaris, Callistoctopus macropus, and Macrotritopus defilippi are classified as cosmopolitan species in distribution. Considerably, the species Eledone moschata are widely distributed in the Mediterranean Sea.

Fluctuations of some Physico-chemical parameters with depth in the Egyptian Mediterranean waters off Alexandria during winter 2016

The current study presented a deep insight on water quality assessment of the Mediterranean Sea off Alexandria coast based on the data of the following hydrographical parameters; pH, salinity, dissolved oxygen (DO), oxidizable organic matter (OOM), and total alkalinity (T. Alk.) in nine sectors (Sidi-Krier, El-Mex, El-Dekhaila, Eastern Harbour, El-Shatby, San-Stefano, El-Montazah, Abu-Qir Bay Head and Abu-Qir Bay) represented by 41 stations along the Egyptian Mediterranean coast off Alexandria city during winter 2016. The overall averages of the hydrographical parameters at the surface and various seawater depths (10–200 m) revealed that the pH levels varied from 8.07 to 8.16, salinity values reflected the range of 38.00-38.66 PSU which is consistent with the Mediterranean water salinity (38.50 PSU). The overall average of the DO showed the range of 4.48-6.60 ml/L. In the meantime, the OOM and T. Alk. demonstrated the ranges of (1.02-2.37 mgO2/L) and (2.87-3.16 mmol/L), respectively. Not many variations in the pH values with depths were observed. Also, the variations in the other parameters were minimal. The Principal Components Analysis (PCA) showed a good correlation between the pH and each of salinity as well as T. Alk. which is consistent with the reported data for the Mediterranean water.

Biometric characteristics of Trachinus araneus Cuveir, 1829, Trachinus draco Linnaeus, 1758 and Trachinus radiatus Cuveir, 1829 (Pisces; Trachinidae) from the Egyptian Mediterranean waters

The biometric characteristics of Trachinus araneus, Trachinus draco and Trachinus radiatus from the Egyptian Mediterranean waters at the West of Alexandria City, were studied. In total, 105, 96 and 55 specimens of these three Fish species were sampled, respectively, by the use of bottom trawls operated in the sectors of El-Dabaa and Sidi Abd El Rahman. The morphological characteristic and related index ratio were determined. The results showed that T. araneus total length varied from 10.9 to 30.0 cm TL with mean length of 19.87 ± 5.43 cm TL and a number of horizontal dots appear to be distributed along the lateral line, T. draco total length was 11.8 to 27.6 cm TL with a mean length of 17.85 ± 4.23 cm TL, and specimens of this Fish species showed yellow vertical oblique lines on the body. On the other hand, T. radiatus is characterized by a total length of 10.6 to 35.0 cm TL with a mean length 18.04 ± 4.87 cm TL, and by circular brown dots spread on the whole body and head. Furthermore, these three Fish species have poisonous spines, one on each operculum, and both spines on the internal border of the dorsal part of each eye orbit. The morphometric regression of each morphometric character showed close agreement between the observed and calculated values.

Comparative taxonomical studies on the Egyptian Mediterranean Squids

Squids are known to be commercially important around the world. Worth mentioning it constitutes a major part of the Egyptian fishing industry. This study aims to differentiate between the teuthoid species dwelling in the Egyptian Mediterranean waters. Squid Specimens were obtained from the fishing trawlers. The specimens were photographed by a CanonG7X digital Camera and the different organs were illustrated using a zoom stereoscopic WildM8 microscope provided with its special Camera Lucida drawing tube.