Evaluation of fishery impacts on whiting (Merlangius merlangus L., 1758): a historical comparison of life history traits.

This thesis work aims to evaluate the actual impact of fishing pressure on the North Adriatic population of Merlangius merlangus. For this purpose, otoliths of the aforementioned population sampled at a distance of thirty years were used: a first set of otoliths comes from sampling carried out between 1990 and 1991, while a second series of samples was collected between November 2020 and November 2021. Furthermore, data relating to the size and sex of the specimens were collected, in order to reconstruct the population structure and carry out a temporal comparison to detect any differences. The removal by humans of larger individuals through fishing and the constant fishing pressure exerted on this species, results in changes in life history traits such as growth rate, age/size at sexual maturity, as well as on the maximum size and on the number of age classes present in the population. The reading of the otoliths and the consequent age estimation of the individuals belonging to the Adriatic population, together with the determination of individuals’ sex and total length, allowed - at least in part - to reconstruct the structure of the current population and to compare it with the past one. In this way an attempt was made to identify at least some of the effects of fishing pressure on this commercially exploited stock.