Abstract
Data on the biology of Dasyatis pastinaca are absent from the Ionian Sea and only a few studies were conducted in the Mediterranean Sea. Some biological and ecological aspects of D. pastinaca were investigated between November 2019 and February 2020 in the central Mediterranean Sea. In particular, we investigated several morphologic, population and ecological aspects of the species. The analysis of the stomach contents showed that D. pastinaca is a generalist carnivorous, mainly feeding on small crustaceans and polychaetes. The Levin’s index value (Bi) was 0.85. The sex ratio showed no significant differences from 1:1 ratio. Females were larger than males, but no statistical differences were found in disc width-weight and total length-disc width relationships between sexes. Most of the specimens caught were juveniles and inhabit shallow sandy bottoms.
Highlights
Elasmobranchs are key top predators in most marine environments and play an essential role in regulating and structuring marine ecosystems [1,2]. Due to their low fecundity and delayed age at maturity, elasmobranchs are highly vulnerable to fishing activity and are often affected by high by-catch rates [3,4]. All this is reflected in the dramatic decline of shark and ray populations and, as demonstrated by several researches conducted in the Mediterranean Sea over the last decades, most species of elasmobranchs have dramatically declined in number mainly due to overfishing and illegal fishing [5,6,7,8,9]
The sex ratio of the fish caught during the study period indicates that there is no sexual segregation in juveniles of D. pastinaca
Females showed larger sizes than males, but no significant differences were found in disc width-weight and total length-disc width relationships between the two sexes
Summary
Elasmobranchs are key top predators in most marine environments and play an essential role in regulating and structuring marine ecosystems [1,2]. Each specimen was weighed and measured (disc width and total length).
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