New Report of Zu cristatus (Bonelli, 1819) in the Ionian Sea with an In-Depth Morphometrical Comparison with All Mediterranean Records

Abstract

Monitoring the occurrence and distribution of rare fish species is essential, especially in a semi-closed basin such as the Mediterranean Sea. Biologically interesting species often represent fishing waste (being part of the by-catch) and therefore are not retained, leading to a huge gap in data collection. Here we report about the occurrence in the Ionian Sea of a Zu cristatus (Bonelli, 1819) specimen, a mesopelagic fish from the order Lampriformes considered rare in the whole Mediterranean basin. The sample was captured at a depth of 720 m off the coast of Noto (Sicily, Italy) by deep-sea longline fisheries. The biometrics and meristic data were compared with all the available data on specimens previously reported in the Mediterranean Sea. It is interesting to note that, among the few records in the literature, most reports mention a lower depth range for this species. In fact, it is quite known that juvenile specimens of Z. cristatus were frequently found in shallow waters, while information about the biology of the adult stage is scarce, indicating they would seem to prefer much deeper environments. Considering the difficulty to collect data on this rare fish, this contribution can help to improve the knowledge about its distribution.

First confirmed record of Zu cristatus in the Mediterranean coast of Israel and the eastern shores of the Levant

“…It lacks the first six dorsal rays but their bases remain. In addition, the absence of a pelvic fin is a natural known phenomenon that occurs during growth and after metamorphosis, the pelvic fin of some specimens degenerates (Bauchot et al, 1984;Oliney, 2002;Albano et al, 2022a). Genetic diversity revealed a shallow genealogy over wide geographic distances, although only six previously published sequences were available for comparison.…”

“…In subsequent years, it was reported from various locations in the Mediterranean (Albano et al, 2022a). Palmer (1986) and Fischer et al (1978) included the entire Mediterranean including the eastern shores in its distribution range.…”

“…This specimen was not saved. Therefore, Goren & Galil (2015) and Albano et al (2022a;2022b) did not include Zu cristatus as occurring in the Levant.…”

Intra-population variability of the saccular, utricular and lagenar otoliths of the garfish Belone belone (Linnaeus, 1760) from South-Western Ionian Sea (Central Mediterranean Sea)

“…It is an opportunistic predator that switches its prey preferences from crustaceans (e.g., copepods, decapods larvae, amphipods) to teleost fishes (e.g., clupeids, engraulids, horse mackerels), according to its size and the preys’ availability [ 18 – 21 ]. Additionally, it is among the principal preys of larger pelagic fishes and marine mammals [ 22 – 24 ]. Due to its high commercial and ecological value, many studies have been performed on the biology of this species.…”

Intraspecific variability of the saccular and utricular otoliths of the hatchetfish Argyropelecus hemigymnus (Cocco, 1829) from the Strait of Messina (Central Mediterranean Sea)

“…The growing impact of human activities (especially fisheries [41][42][43][44]) on Mediterranean deep environments has led the scientific community to focus on meso-and bathypelagic communities. Due to their vertical migrations and trophic relationships, these play a fundamental ecological role in the energy flowing and carbon transport between different marine domains [45][46][47][48][49][50][51][52][53][54]. Mesopelagic fishes show a great abundance in biomass, being the main component of the deep scattering layer (DSL) and mesopelagic zone, and the most abundant vertebrates on earth for their density and diffusion in all the Oceans [55,56].…”