Natural hybridization between immigrant narrow–barred Spanish mackerel Scomberomorus commerson (Lacepède, 1800) and endemic West African Spanish mackerel Scomberomorus tritor (Cuvier, 1832) in the Egyptian Mediterranean coast

Abstract

Immigrant narrow–barred Spanish mackerel, West African Spanish mackerel and specimens with an external appearance somewhere between these putative parents were collected from Abu Qir Bay, East Alexandria, Egypt. The hybrid index results and univariate and multivariate analysis indicated a natural hybridization between these two species. The discriminant function analysis successfully classified individual fish in the data to one of the three fish groups. Squared Mahalanobis distances extracted from the groups indicated the three groups were clearly distinct from each other. Moreover, distances between the hybrid and Scomberomorus tritor were longer than those of the hybrid and S. commerson. The mean values of the condition factor for the hybri were significantly higher than those of S. commerson. Natural mortality of the hybrid was significantly lower than that of the exotic parent (S. commerson), indicating that the environmental conditions in the examined region are more suitable for the hybrid type species than for the invasive parental species.

Anatomical oropharyngeal cavity specialisations in the cutlassfish (Trichiurus lepturus, Linnaeus, 1758)

“…The carnivorous T. lepturus feeds on cephalopods, bony fishes and euphausiids as sub‐adults and adults (Martial et al, 2020; Martins et al, 2005). Bakhoum (2007) revealed that Trichiurus from the Egyptian coast, especially at AbuQir, fed on crustaceans when they were smaller than 30 cm in size, while fish larger than 59 cm tended to eat fish. The oropharyngeal cavity in predatory fish plays several roles including seizing and maintaining grip on prey (including other fish), food selection and the rejection of unwanted excretory particles swallowed by the fish.…”