Reproductive biology of greasy grouper, Epinephelus tauvina and coral hind grouper Cephalopholis miniata (Family: Serranidae) in the southern Red Sea, Shalatien, Egypt

Groupers are the main component of commercial fisheries in the Red Sea. The reproductive biology of Epinephelus tauvina and Cephalopholis miniata collected at the Shalatien landing site in the southern Egyptian Red Sea were investigated from January to December 2017. A total of 212 specimens of E. tauvina with a total length range of 23.6 to 70.3 cm and 243 specimens of C. miniata with a total length range of 17.4 to 42.1 cm were examined. Females of E. tauvina and C. miniata accounted for 61.7 and 61.9% of the total fish sampled, showing a 1:1.61 and 1:1.63 male-to-female sex ratio, respectively. The monthly distribution of maturity stages and gonadosomatic index values showed that the spawning season for both sexes was extended from April to October for E. tauvina and from April to September for C. miniata. The lengths at first sexual maturity of the males and females of E. tauvina were estimated at 49 and 48.1 cm, respectively, while those for C. miniata were estimated at 23.2 and 22.7 cm, respectively. All our results can help in the proper management of these valuable resources

Lead-induced heat shock protein (HSP70) and metallothionein (MT) gene expression in the embryos of African catfish Clarias gariepinus (Burchell, 1822)

The enhanced expression of heat shock proteins (HSPs) and metallothionein (MT) can be detected in response to many environmental stressors, including exposure to heavy metals. We identified partial mRNA sequences for beta2-microglobulin (ß2m), heat shock cognate 70 kDa protein (HSP70), and MT in embryos of the African catfish Clarias gariepinus (Burchell, 1822). Levels of these transcripts were assessed using reverse-transcription quantitative polymerase chain reaction (RT-QPCR) after embryos of various stages were exposed to different concentrations of lead nitrate. ß2m gene expression exhibited a continuous increase over time. Neither HSP70 nor MT were upregulated, supporting the well-known sensitivity of these organisms to environmental pollutants. Interestingly, the partial MT and HSP70 mRNA sequences revealed an intimate phylogenetic relationship with these proteins in siluriforms. These partial sequences were more closely related to salmoniform proteins than to cypriniform proteins. The expression levels of HSP70 and MT were lower in embryonic tissues exposed to high concentrations of lead (500 µg/L), which impaired the fish's coping strategy via toxication at the cellular level. In conclusion, early developmental stages appear to be particularly vulnerable to lead and fail to activate the typical coping mechanisms. Therefore, these early life stages may not be suitable to characterize concentration-dependent toxicity. Keywords: Expression of stress proteins, RT-QPCR, Fish embryos, Heavy metal pollutio

Ageing Nile tilapia (Oreochromis niloticus): A comparative study between scales and otoliths

This study is the first to compare age estimates based on scales and otoliths of the Nile tilapia, Oreochromis niloticus, from Lake Nasser, Egypt. Ageing precision between readers was estimated by calculating the percent agreement between three independent readers, and the coefï¬cient of variation (CV) ages estimated from otoliths and scales. The relation between the total length of fish and the radius of its scale and otolith was determined and appeared to be linear. The estimated age composition of the O. niloticus included six age groups estimated using scales and five age groups estimated by otoliths. The relative precision (CV and SD) of ages estimated from otolith was higher than that from scales. Higher percentages of agreement of overall annuli identification and age assignment between readers were noted in otoliths comparing to that in scales. Scale showed some inaccurate estimation in the age of fish older than 4. The precision and bias information in this study will be beneficial to fisheries professionals in assessing the age of Nile tilapia and other cichlids in the future

Some reproductive aspects of the areolate grouper, Epinephelus areolotus from the Gulf of Suez

Groupers are primary targets of artisanal, recreational and commercial fisheries in the Red Sea and Gulf of Suez. The reproductive biology of the areolate grouper Epinephelus areolatus, collected from the main landing site in the Gulf of Suez, was investigated, and females accounted for 87.2% of the total fish sampled for a 1:6.8 male to female sex ratio. The monthly analysis of gonado-somatic index values and the monthly distribution of maturity stages showed that the spawning season of E. areolatus was restricted to the period from June to August for both sexes. The length at which 50% of the fish were mature was 24.3 cm for males and 25.5 cm for females, and by referring this value to the corresponding age, it was determined that E. areolatus first attains sexual maturity at 2.04 years for males and 2.23 years for females. The species was characterized by high fecundity, with a mean of 169,952 to 1,433,022 ova per female, and the relative fecundity ranged from 7,081 to 32,569 ova for individuals with a total length between 24.0 and 44.0 cm. The results of this investigation can be utilized to develop suitable management practices for groupers and for planning appropriate control measures. Keywords: Sex ratio, Spawning season, Fecundity, Epinephelus areolatus, Gulf of Sue

Catch

Catch and effort (CPUE) of the purse-seine using light, age and growth of lessepsian fish “Etrumeus teres” from the Egyptian Mediterranean waters were studied in the period 2008. It was found that, the average annual catch (CPUE) was 1.7 (ton/boat/night). The catch diversity was composed of seventeen different species. Clupeids were the dominant 74.1% of the total catch. Seven lessepsian species were involved and constituted 41.18% and 19.01% of the total number and weight of the catch, respectively. Round herring E. teres was the highest one of these immigrants, accounting for 10.93% of the total catch; it exhibited the highest average values of the catch during winter and autumn (19.7% and 19.2%, respectively). The exponent “b” of length-weight was 3.052 revealing positive allometric mode of growth. The length range was 9–25 cm for combined sexes with an average of 17.22 ± 3.29 cm while the smallest lengths were recorded during the summer season. The highest condition factor (k) was recorded in July, while the lowest one was in February, this factor increased with the increase in fish length. Round herring, E. teres reached to five years that was determined by otolith. Growth parameters; L∞ were 31.71, 29.058 and 30.26 cm for males, females and combined sexes, respectively. Growth coefficients (K) were 0.214, 0.246 and 0.225 year−1 for males, females and combined sexes, respectively; values of to were −0.776, −0.686 and −0.744 year−1 for males, females and combined sexes. Growth performance indexes (Ø) were 2.33, 2.31 and 2.31 for males, females and combined sexes, respectively. This study reflected the importance of such fishing gear in the Egyptian marine fisheries. Round herring “E. teres” as lessepsian species is predicted to be of economic value in the marine fisheries and give the positive impact of the lessepsian migration. The age of E. teres was five age groups that were higher than those from the Red Sea reflecting the good establishment of such immigrants in the new habitat. This may be ascribed to the environmental variations between different localities and due to the low exploitation rate of such new immigrant species in the Egyptian Mediterranean waters

Regional variability in remotely sensed data with respect to the distribution of some snapper fishes (Family: Lutjanidae) between the Red Sea and the Arabian Gulf

Geographically dissimilar aquatic ecosystems from similar origin promote our comprehensive understanding of the role of abiotic factors in the distribution of biodiversity from one extreme, and they provide outstanding examples of convergent evolution in biological diversity on the other extreme. A new approach to monitoring and management of fisheries and marine ecosystems is required. Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) concentration are both crucial environmental variables that have significant impacts on marine ecosystems, particularly for fishes and overall aquatic life. These factors play important roles in shaping the health, distribution, behavior, and productivity of marine organisms. In the current study, Modis-aqua daily SST and Chl-a derived data from 2002 to 2022 were loaded into MATLAB, analyzed, and compared between the Arabian Gulf and Red Sea (Egyptian territory). Additionally, the catch of the family Lutjanidae (snapper fish) was recorded in 2002 to determine the distribution of napper fish species and compare production (based on data available from 2002 to 2022) in relation to SST and Chl-a variabilities. According to the current study, Chl-a in the Arabian Gulf showed narrow fluctuations during the winter and spring months, but higher than the Red Sea, and had a significant increase in sea surface temperature (SST) throughout the summer compared to the Red Sea. Spatial and temporal interaction between the means of Chl-a and SST was significantly different (P < 0.01). On the other hand, the results showed that different thermal stresses were experienced by the Arabian Gulf and the Red Sea, as shown by the total positive SST anomaly and by events occurring in different trends. Both the total catch of lutjanid snappers and the species identified by DNA barcoding varied significantly between the two geographical regions. The current work suggests using large-scale, fisheries-independent data to map the main gradients in marine fish community and species abundance and forecast their future distribution in connection to climate change

Effects of penconazole and copper nanoparticle fungicides on redbelly tilapia, Coptodon zillii (Gervais, 1848): Reproductive outcomes

Several effective fungicides have recently been applied, but they can harm ecosystems and non-target organisms. The findings of this study should be helpful to evaluate the reproductive response of redbelly tilapia, Coptodon zillii, of both sexes upon exposure to 0.8 and 1.6 μg/L penconazole and 7.5 and 15 mg/L copper nanoparticle as fungicides for three months. The gonadosomatic index of males increased in the penconazole groups in parallel with testosterone. A significant increase was observed in estradiol and progesterone of penconazole and copper nanoparticle groups. In testicular homogenate, there was a significant decrease in superoxide radical in penconazole (I) and penconazole (II) groups and CAT of penconazole (I) and copper nanoparticle (I) groups, along with a significant increase in nitric oxide (NO) of Cu-NP (II) group. In ovarian homogenate, a significant increase in NO of penconazole (I) group and lipid peroxides of copper nanoparticle (I) group, along with decrease in CAT of penconazole (II) and copper nanoparticle (I) groups and SOD of penconazole (II) and copper nanoparticle (I) groups were found. The histopathological examination indicated gross deteriorations in the gonads of fish exposed to the fungicides except in the copper nanoparticle (II) group. These findings suggested the reproductive burden in C. zillii following exposure to the investigated fungicides by disrupting gonadal sex hormones and inducing redox imbalance and cytopathological abnormalities. It is recommended to reduce the flow of these materials to aquatic areas particularly the natural fisheries and artificial hatcheries