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Understanding how environmental factors affect species distribution is crucial for the conservation and management of marine organisms, especially in the face of global changes. Whiting (Merlangius merlangus) is a demersal cold-temperate fish, considered a 'relict species' in the Adriatic Sea. Despite its significance to commercial fisheries in the region, the specific drivers behind its spatial and temporal patterns have not been thoroughly examined. Here, we fitted a set of Generalized Linear Mixed Effects Models to data collected in the Northern and Central Adriatic from 1999 to 2019 during the Mediterranean International Trawl Survey to investigate the potential influence of depth, seafloor temperature and seafloor dissolved oxygen on the annual biomass density and spatial distribution of whiting in the spring-summer season. Our results showed that depth, and to a lesser degree temperature and oxygen, are important predictors of whiting distribution in this period, with preferences for depths of ~ 45 m, temperature of ~ 15.4°C and dissolved oxygen > 5.5 ml L-1. We predicted a persistent core area of distribution in front of the Po River Delta, in the Northern Adriatic Sea, while the density progressively declined towards the Central and Southern Adriatic Sea along the Italian coast. Additionally, the temporal trend exhibited high fluctuations over the years, occurring in cycles of 3 to 4 years. Finally, by comparing the biomass density estimates obtained under optimal conditions with those derived from the actual values for each variable, our analysis revealed that temperature had a pronounced and general impact on biomass density in the northern survey area (predictions revealed a density reduction of approximately two-thirds), while oxygen displayed a minor and more localized influence. This work deepens the current knowledge about the ecology of whiting in the Adriatic Sea and provides support for the conservation and management of this species.

The age and growth of the slender lightfish Vinciguerria attenuata are investigated for the first time by the analysis of otolith microstructure. A total of 242 individuals (standard length range = 15.3–39.0 mm) are collected from the Strait of Messina (central Mediterranean Sea). The analysis of the length–weight relationship highlights a hyper-allometric growth for all specimens, while when males and females are analyzed separately, the results point out an isometric growth for males and hyper-allometric growth for females, although no statistical differences emerge comparing sex curves (p-value = 0.06). Microincrement readings are considered valid only for 214 sagittal otoliths. Microincrement counts range from 31 to 49 (average = 39.9) in the otolith central zone, 28 to 53 (average = 43.2) in the middle zone, and 15 to 332 (average = 136.1) in the external zone. Overall, total microincrements range between 75 and 418. Different growth models (von Bertalanffy, Gompertz and logistic models) are taken into account to select the best-fitting model in describing the growth patterns in V. attenuata. The logistic growth model is selected as the best-fitting model, and its parameters for all individuals are L∞ = 38.597, k = 0.0104 and I = 122.4.