Reproductive biology and growth of the alien Red Sea goatfish Parupeneus forsskali (Fourmanoir & Guézé, 1976) off the coast of Cyprus

Abstract

Goatfish (family Mullidae) are of great commercial and economical importance around the world, including in the Mediterranean Sea, where six goatfish species have been recorded. Four of those species are alien to the Mediterranean, migrating either from the Atlantic Ocean or from the Red Sea through the Suez Canal. The most recent mullid species to arrive in the Mediterranean is the Red Sea goatfish (Parupeneus forsskali), which was first spotted there in the year 2000. P. forsskali is endemic to the Red Sea and the Gulf of Aden, but has increased its range considerably in recent years, spreading throughout the eastern Mediterranean and all the way out to Tunisia in the west. It was first confirmed around Cyprus in 2014 and has since then established a thriving population around the island, already becoming commercially important. Its arrival in Cyprus seems to have negatively impacted the populations of native goatfish species through competition, indicating that it could become invasive at some point in the future. In the present study, the spawning season and gonad development of P. forsskali off the coast of Cyprus were studied, along with important biological parameters. 466 individuals were sampled from the southern coast of Cyprus, from November 2020 to October 2021. Macroscopic and histological analyses of the gonads indicated six clear maturity stages for both ovaries and testes. The gonadal maturity stages and the gonadosomatic index indicated that P. forsskali spawns in the summer months, with the peak of the spawning season in July. Males were bigger, heavier, and more abundant than females, but their length-weight relationship did not differ. The overall length-weight relationship was found to be TW = 0.0065 x TL3.17, indicating positive allometric growth. The size at first sexual maturity (L50) did not differ between males and females, and was 14.3 cm for all fish combined. Five age groups were identified from the length-frequency distribution (0-4 years old). Age group 1 (one year old fish) was the most dominant one, containing almost 54% of the sampled individuals. The parameters of the von Bertalanffy growth function were L∞ = 31.81 cm, K = 0.27 year-1, and t0 = -1.67. Overall, this study provides information on the spawning season of the Red Sea goatfish, detailed descriptions of its gonadal maturity stages which can be helpful to other researchers studying the species, and estimations of biological parameters that are important for fisheries management.