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The objective of the current study was to describe the female reproductive characteristics of populations of the non-indigenous shrimp Penaeus latisulcatusoff the Egyptian Mediterranean coast. P. latisulcatuswas sampled from the commercial catch of Boughaz El-Maadiyah's landing center off the Mediterranean coast between July 2020 and June 2021. This study focused on describing maturity stages, calculating the gonadosomatic index (GSI), determining the spawning season, and measuring the size at first maturity of female P. latisulcatus. The stages of ovarian development were divided into six stages; i.e., immature, early maturing, late maturing, nearly ripe, ripe, and spent. A prolonged spawning season was identified, extending from the summer season to autumn and showing a peak in August. The GSI followed the same pattern of ovarian maturation and confirmed the spawning season of P. latisulcatus.As revealed, 50% of female individuals attained maturity at a total length of 11.34 cm. Hence, this study provides fundamental and helpful information for understanding the reproductive dynamics of P. latisulcatuson the Egyptian Mediterranean coast as a new habitat for its propagation. This information also helps in providing the proper management of fisheries and conservation of this shrimp species, which can be useful for aquaculture processes as well.

Penaeus latisulcatus(Kishinouye, 1896) is considered one of the most economically important penaeid shrimp species in the Egyptian Red Sea. Recently, it appeared in the Egyptian Mediterranean catches. The present study is concerned with the estimation of growth, age and population characteristics of the non-indigenous P. latisulcatuscollected between the months of July 2020 to June 2021 from the landing fishing center of Boughaz El-Maadiyah (Egyptian Mediterranean coast). A total of 2214 individuals were collected monthly. The results showed that the females to males ratio was 1:0.98. According to the Chi-square test, there was no statistically significant difference between the sexes (X2 = 0.181, df = 1, P > 0.05). The distribution of the length frequency showed that the females varied from 5.0 cm to 19.2 cm (TL) with a mean length of 11.73 ± 2.78 cm, while the males ranged from 5.3 cm to 17.1 cm (TL) with a mean length of 10.97 ± 2.06 cm. Positive allometry was detected for the total length-total weight relationship. The parameters of von Bertalanffy were L∞ = 20.56 cm, K = 0.99 yr−1and to = −0.178 yr−1for females, L∞ = 18.68 cm, K = 1.05 yr−1and to = −0.172 yr−1for males, and L∞ = 20.74 cm, K = 0.90 yr−1and to = −0.196 yr−1for the combined sexes. The expected age of females and males were 2.6 and 2.2 years, respectively. According to the parameters obtained, the current exploitation rate of the population of P. latisulcatuswas estimated at Ecur. = 0.59. The results indicated that the population of P. latisulcatusis being highly exploited in Boughaz El-Maadiyah landing center (Egyptian Mediterranean coast). Hence, it is important to manage the P. latisulcatusshrimp resources in the studied area. Furthermore, similar studies are recommended for P. latisulcatusalong the Egyptian Mediterranean coast to evaluate variations between populations in different fishing areas. Moreover, further studies are needed about the new aspects of the reproductive activity of this species as well as its aquaculture to estimate its growth rate experimentally.

A total of 1457 random specimens of the newly established population of Metapenaeus affiniswas collected monthly from the shrimp commercial catch at Boughaz El-Maadiyah landing center (Mediterranean Sea, Egypt) during the period from July 2020 to June 2021. This study aims to shed light on the growth pattern and stock assessment of this newly established species. The results showed that the catch of M. affinisvaried in lengths between 5.4 cm and 16.0 cm TL. At length 13.5 cm, the population was composed of 100% females. The test of the allometric coefficients “b” of the total length (TL) – carapace length (CL) relationship showed negative allometry growth for males, females, and sexes combined. The values of “b” for the length-weight relationship reflected isometric growth for males, and a pattern of positive allometric growth was shown for females and sexes combined. The overall sex ratio (F:M) was 1.00:0.58 and the Chi-square test reflected high significant differences (χ2 = 100.68; df = 1; P < 0.01). Five cohort groups representing 2 yr for females and four cohort groups representing 1+yr for males were identified by Bhattacharya's method. For combined sexes, the growth parameters were L∞ = 19.849 cm, K = 0.242, and to = −0.872. The study of fishery parameters revealed that M. affinispopulation was still unexploited (Ecur. = 0.38). Further studies are recommended to shed lights on its spawning and nursery grounds in the Egyptian waters. The study of the reproductive biology for this shrimp species is also recommended.

A sample of 347 specimens of the northern brown shrimp Penaeus aztecus,a western Atlantic species, was collected from July 2019 to June 2020 by local bottom trawlers off two fishing areas, Abu-Qir Bay and Ma’deya, east of Alexandria Coast, Egypt. The species identification was confirmed by morphological and genetic characters. Some aspects of the species’ morphometry and its monthly abundance were briefly discussed. The collected adults were observed from May to November with higher percentage of occurrence in August (29% of total shrimp catch). Sex ratio was 1: 1.2 (F: M). The total length of the adult specimen ranged from 91 mm to 210 mm. COI sequences gave a maximum identity of 99.56% with P. aztecusfrom Texas and USA, and 99.44% with species from the Eastern Mediterranean. The genetic distance among the studied species from Egypt, USA and the Eastern Mediterranean ranged from 0.2 to 0.7%. The results of this study suggest that P. aztecusmay become a new resource for coastal Mediterranean shrimp fisheries.

This study describes the gonads of Lithophaga lithophaga(Linnaeus, 1758) inhabiting the coast of Alexandria City, Egypt, on the Southeastern Mediterranean Sea. Investigated samples were collected from five sites situated between Sidi Gaber and Montaza. Seven hundred and forty six individuals were collected through one year from December 2017 to November 2018. Two hundred and thirty eight specimens with shell length of 46.83 ± 12.28 and total weight of 7.29 ± 5.74 were selected representing the monthly abundance and were used for histological analysis. The sex of L. lithophagais dioecious with no sexual dimorphism and distinct by the gonad color. However, differentiation of sex was accurately defined histologically. The investigated animals showed a statistically unbalanced sex ratio. The male to female ratio was 3.5:1. However, the results of the present study showed that the ratio of males decreased as the shell length increased. The developmental stages of gonads were identified as five stages. The spawning activity occurred during July and August, while the spent stage was found mostly in September. Furthermore, the results showed that L. lithophagahas one annual gonadal cycle. There is a clear correlation between the maximum values of condition index and meat yield of these studied date mussels with their spawning activity during July–August, followed by a decrease in these values from October to the following June. This result can be a more validating method to identify the reproductive conditions of L. lithophaga’s population. Finally, each gonad developmental stage was described microscopically in details for both sexes.

The reproductive cycle and sexuality studies of the mussel Brachidontes pharaoniswere carried out during the period from March 2016 to February 2017 along Alexandria Coast, Egypt. The gametogenic development of the gonads and the spawning duration under natural conditions were also studied. Histological preparations of a total of 307 individuals were examined monthly and the results showed that 44% were males, 51.8% females, 3.9% were sexually undifferentiated individuals and only one individual was hermaphrodite presenting 0.33% of the examined population, which indicates that B. pharaonisis gonochoristic. Histological studies showed that the gametogenic cycle could be divided into five stages of maturation. Also, an extended period of spawning starting from April to October was detected. Spawning activity of the studied species was in May to July and October. Gonad index reached its maximum in May, August and October when most of the individuals were in ripe and spawning activity. Sexes were distinct all over the studied size classes except those individuals in resting condition (stage 0). The smallest ripe gonads of both sexes were observed at 8.0–12.0 mm shell lengths. Photomicrographs of gametogenic cycles of both male and female mussels are included.

Brachidontes pharaonis(Fischer, 1876) was widely reported to cover completely hard substrates especially rocky shores with higher density in mid-littoral zones forming mytilid beds along Alexandria Coast, Egypt. During our study on the reproductive cycle of this species, one case out of 307 examined specimens was found to be hermaphrodite representing only 0.33% of the total sample. It had a shell length 28.25 mm and was collected during January 2017. The sex ratio of this population is different from 1:1, although this deference was not significant (X2 = 11.118, df = 11, P > 0.05). In this contribution, this case of hermaphroditism in B. pharaonisis described.The histological study showed the presence of male and female gametes in the same follicle and this was the most common situation in both lobes of the mantle. The male zone was showing different stages of spermatogenesis together with the female zones showed different stages of oogenesis with occurrence of young oocytes attached to the follicle wall.

An unexpected new Metapenaeusshrimp species has arrived to the coastal water of Alexandria City, Egypt. Morphological and molecular studies were conducted for its identification. The results revealed that it is the Indo-West Pacific species, Metapenaeus affinis(H. Milne Edwards, 1837),which is considered as a new addition to the already present local penaeidaespecies; Metapenaeus monoceros(Fabricius, 1798) and Metapenaeus stebbingi(Nobili, 1904). Large numbers of Metapenaeus affiniswere observed and collected by the Egyptian fishermen from the coastal waters of Alexandria City, Egypt, during the study period (2020-2021), which indicates its establishment in the area. A recommendation was presented for further studies regarding the suggested ways of introduction and the prediction for future new species appearance. Such phenomenon requires international efforts to deal with the non-indigenous species’ entries that are recently intensified on the global and regional level.