Some population characteristics of cartilaginous fish incidentally caught with demersal trawls in the black sea coasts

Cartilaginous fish are marine organisms, some of which are in decline and some of which are under protection, and which have a very important place in the ecosystem and food chain of the Turkish seas, as in all oceans and seas of the world. This study examined the fisheries biology and population dynamics of cartilaginous fish species that were accidentally caught as non-target species in bottom trawl nets by commercial fishing vessels during the 2023-2024 and 2024-2025 fishing seasons on the Samsun and Sinop coasts of the Black Sea. As a result of a total 174 demersal trawl tows carried out during the study, it was determined that the species of thornback ray (Raja clavata Linnaeus; 1758), stingray fish (Dasyatis pastinaca Linnaeus; 1758) and picked dogfish (Squalus acanthias Linnaeus; 1758) living in the Black Sea were incidentally caught in fishing gear as cartilaginous fish. It was determined that the thornback ray and stingray fish showed positive allometric growth, while the picked dogfish showed negative allometric growth. The end of the study, the Von Bertalanffy Growth Equation (VBBD) parameters (L∞, K and to, mortality rates (Z, M, F) and exploitation rates (E) of the species were estimated. L∞, K, to values for the species were calculated as 187.3 cm, 0.207 year-1, -2.47 year-1; 277 cm, 0.069 year-1, -2.89 year-1, 152.9 cm, 0.16 year-1, -2.18 year-1, respectively. It was determined that stock exploitation rates of the species were quite high; E values were estimated as 0.69, 0.61 and 0.81, respectively. The study results were compared with the results of other research on these species. In addition, some suggestions were made on the protection of cartilaginous fish species incidentally caught in demersaltrawl nets, their sustainability, minimizing unintentional catching, and the methodologies that can be applied.