Population Growth of Thunnus thynnus and Vulnerability to Fishing along the Syrian Coast (Eastern Mediterranean Sea)

Abstract

A total of 233 random samples of Thunnus thynnus were collected from Syrian seawater between July and October 2023. These samples were subjected to advanced analytical techniques, including artificial neural networks and fuzzy logic. The largest individual caught measured 218 cm fork length and was estimated to be 10 years. The Bertalanffy growth equation: FLt = 361.43 (1-e-0.079 (t + 1.210)) provided insight into the growth pattern of the studied Th. thynnus population, indicating negative allometric growth (b = 2.94). The growth performance index (Φ’) was 4.01. The mortality coefficients were estimated to be Z = 0.56 y-1, F = 0.39 y-1, M = 0.17 y-1 and E = 0.70 y-1, with a survival coefficient (S) of 0.57 y-1. The analysis revealed significant population growth patterns at a fishing pressure (FP) value of 60, but also identified a high fishing vulnerability (FV) value of 67. This vulnerability represents a significant threat to the fish population. The findings of this study underscore the significance of implementing conservation measures for the long-term sustainability of the species. They also contribute to our understanding of the growth, mortality, and vulnerability of Th. thynnus to fishing, which will inform future research and management strategies.