Histological and ultrastructural characterization of the dorso-ventral skin of the juvenile and the adult starry puffer fish (Arothron stellatus, Anonymous 1798).

BACKGROUND: The starry puffer fish (Arothron stellatus, Anonymous, 1798) is a poisonous tetradontidae fish inhabiting the Red sea. The skin constitutes an important defense against any external effects. The study aims to characterize the dorso-ventral skin of the juvenile and the adult starry puffer fish using light and scanning electron microscopies. Twenty specimens of juvenile and adult fresh fishes were used. RESULTS: The scanning electron microarchitecture of the skin of the juvenile and adult fish showed delicate irregular-shaped protrusions, and well-defined bricks-like elevations on the dorsal side and interrupted folds as well as irregular-shaped protrusions on the ventral side. In adult fish, the patterned microridges of the superficial and deep epithelial cells (keratinocytes) were larger and well-defined in the dorsal skin than in the ventral side, the contrary was seen in the juvenile fish. The microridges were arranged in a fingerprint or honeycomb patterns. The openings of the mucous cells were more numerous in the dorsal skin in both age stages but more noticeable in adult. Furthermore, the sensory cells were more dominant in the juveniles than the adults. The odontic spines were only seen in adult. Histologically, few taste buds were observed in the epidermis of the dorsal skin surface of the adult fish. Both mucous and club cells were embedded in the epidermis of the juvenile and adult fish with different shapes and sizes. Melanophores were observed at the dorsal skin of both juvenile and adult fishes while fewer numbers were noticed at the ventral surfaces. Several dermal bony plates with different shapes and sizes were demonstrated in the skin of both adult and juvenile fishes. CONCLUSION: The structural variations of skin of the juvenile and adult fishes may reflect the various environmental difficulties that they confront.

Diversity and characteristics of commercial Red Sea fish species based on fish market survey: informing management to reduce the risk of overfishing.

In small-scale fisheries (SSFs), where the sampling of many small boats and landing sites sometimes is not practical, fish market surveys represent an alternative way to obtain key fisheries data. This study analyses the diversity and characteristics of commercial Red Sea fish species landed in the Egyptian coast, including family, species-specific abundance, biomass, size and price by surveying the largest local fish market on the Egyptian Red Sea coast, over the course of a year (July 2021-June 2022) to also reflect any seasonality of these variables. Based on 53 survey visits, a total of 131,795 fish individuals, belonging to 111 species, and 22 families, were identified, recorded and measured. The analysis focused on the 60 most abundant species (104,420 individuals, 15 families). The surveys revealed that the most abundant families were Serranidae, Lethrinidae and Scaridae. Carangidae also was one of the most important families in terms of biomass. The most abundant species were Lethrinus mahsena, Sargocentron spiniferum and Lethrinus nebulosus. About 60% of revenue comes from the four families Serranidae, Lethrinidae, Scaridae and Lutjanidae. In terms of prices, the most expensive categories were species belonging to Serranidae, Lethrinidae and Lutjanidae families, such as Plectropomus pessuliferus marisrubri, Argyrops spinifer, L. nebulosus and Variola louti. The overall mean prices were higher in spring and summer months likely due to tourism flows. The mean size of many species, including the most valuable and abundant ones, is below the length of maturity. These results provide important benchmarks for monitoring future changes and shed important insights for fisheries management. Co-organised Dutch auctions would provide reliable data when combined with a strict monitoring effort to avoid any sale of the catch outside these official auctions. Other monitoring tools and methods are also recommended in the discussion.

Microplastic distribution, abundance, and composition in the sediments, water, and fishes of the Red and Mediterranean seas, Egypt.

This study records the extent of microplastics (MPs) in the surface water, sediments, and fishes of the Mediterranean and Red seas in Egypt. In sediment and water samples, the Ras Gharib station in the Red sea and Damietta and Port Said stations in the Mediterranean sea exhibited the highest microplastic abundance, while the lowest concentration was found in the Ain Sukhna station in the Red Sea and Marsa Matruh station in the Mediterranean sea. Rayon and polyethylene terephthalate were the most frequently found polymers in fishes. The results highlighted the abundant existence of microplastics in sediments, water, and fishes of the Mediterranean and Red seas, thereby improving our understanding of the environmental risks posed by microplastics to fisheries and marine ecosystems and the need for measures to diminish the flux of plastics to the marine settings.