The Adriatic stock of European sardine ( Sardina pilchardus ) has experienced large interannual demographic fluctuations over the last 30 years, with a severe decline beginning in 1991 and continuing until 1997. In the present study, six microsatellite loci were used on a time series collection of otoliths and scales from sampling locations of northern (Chioggia) and southern (Vieste) Adriatic Sea, with the aim to investigate the genetic effects of these stock biomass fluctuations. The northern samples showed significant reduction in observed heterozygosity (H_O) and mean number of alleles (N_a) that explain the genetic diversity variation, while the same parameters turned out to be more stable in the southern samples. In addition, we detected the presence of a genetic bottleneck and low effective population size (N_e) values in several northern samples. Even if the northern and southern Adriatic sardine samples belong to the same genetic stock, the more pronounced decrease in genetic variability recorded in the northern sample led us to speculate that a more intensive fishing pressure and a more pronounced oceanographic isolation of this area could have accentuated the effects of the genetic bottleneck.

The study focused on the macroscopic, histological, and biometric analysis of European hake females in GSA 17 (Central-North Adriatic Sea). From 2013 to 2015, 976 females were collected and analyzed monthly. Though females in spawning conditions were found during the whole year, the trend of GSI showed a peak of the reproductive season from April to July in 2014 and 2015. HSI and K_n reached the highest values in September, after the spawning peaks. In 2013, the trend of these indices did not highlight an evident peak, probably due to an adverse event that occurred in the previous winter in the Adriatic shelf. The length at first maturity (L₅₀) was estimated by macroscopic and histological approaches, resulting in 30.81 cm for the macroscopical length and 33.73 cm for the histological length; both values are higher than the current catching legal size. For the first time in this area, batch and relative fecundity were estimated. Relative fecundity was similar to the Mediterranean and the Atlantic stocks, whereas batch fecundity values were lower compared to other fishing grounds. Overall, the analysis of reproductive parameters plays a fundamental role in the sustainable management of this resource in an area as overfished as the Central-North Adriatic Sea.

A Before–Intermediate–After Multiple Sites (BIAMS) analysis, namely a modified version of the Before–After–Control–Impact (BACI) approach, was used to evaluate the possible effects of fishery management measures implemented in the Pomo/Jabuka Pits area, a historically highly exploited ground for Italian and Croatian fisheries, whose impact may have contributed over the years to the modification of the ecosystem. Since 2015, the area was subject to fishing regulations changing the type of restrictions over time and space, until the definitive establishment in 2018 of a Fishery Restricted Area. These changes in the regulatory regime result in complex signals to be interpreted. The analysis was carried out on abundance indices (i.e., kg/km² and N/km²) of five commercially or ecologically relevant species, obtained in the period 2012–2019 from two annual trawl surveys. BIAMS was based on the selection of a Closure factor, declined in three levels (i.e., BEFORE/INTERMEDIATE/AFTER) and accounting for regulation changes in time, and on three adjacent strata (i.e., “A”, “B”, and “ext ITA”) a posteriori determined according to the latest regulations. BIAMS allowed us to identify early effects (i.e., changes in abundances), overcoming the unavailability of a proper independent control site; furthermore, the selection of adjacent strata allowed the inference of possible interactions among them.

The common sole, Solea solea, is one the most important commercial species in Europe and, within the Mediterranean, the Adriatic basin is the most crucial area for its production. Although the species is overexploited in the basin, data on its trophic ecology are fragmentary, even though this is one of the most important features within the Ecosystem Approach to Fishery. Here, we analysed temporal variations in the feeding ecology of the species by using an integrated approach of stomach contents and stable isotope analyses coupled with the analysis of some condition indices such as the gonadosomatic and the hepatosomatic indices. Changes in diet and trophic level across the years in adult females were clearly linked to the different energetic requirements facing reproduction. Temporal changes throughout the year were mainly related to changes in food availability. This study confirms the opportunistic behaviour of this benthophagous species and its role as a mesopredator, opening new perspectives for further investigations on the effects of the overexploitation of this important fishery resource on the marine trophic web.

Nowadays, overexploitation and climate change are among the major threats to fish production all over the world. In this study, we focused our attention on the Adriatic Sea (AS), a shallow semi-enclosed sub-basin showing the highest exploitation level and warming trend over the last decades within the Mediterranean Sea. We investigated the life history traits and population dynamics of the cold-water species whiting (Merlangius merlangus, Gadidae) 30 years apart, which is one of the main commercial species in the Northern AS. The AS represents its southern limit of distribution, in accordance with the thermal preference of this cold-water species. Fish samples were collected monthly using a commercial bottom trawl within the periods 1990–1991 and 2020–2021. The historical comparison highlighted a recent reduction in large specimens (>25 cm total length, TL), which was not associated with trunked age structures, therefore indicating a decrease in growth performance over a period of 30 years (L_∞90–91 = 29.5 cm TL; L_∞20–21 = 22.8 cm TL). The current size at first sexual maturity was achieved within the first year of life, at around 16 cm TL for males and 17 cm TL for females. In the AS, whiting spawns in batches from December to March, showing a reproductive investment (gonadosomatic index) one order of magnitude higher in females than in males. Potential fecundity (F) ranged from 46,144 to 424,298, with it being heavily dependent on fish size. We hypothesize that the decreased growth performance might be related to a metabolic constraint, possibly related to the increased temperature and its consequences. Moreover, considering the detrimental effects of size reduction on reproductive potential, these findings suggest a potential endangerment situation for the long-term maintenance of whiting and cold-related species in the AS, which should be accounted for in setting management strategies.

Mercury (Hg) is a pollutant that has toxic effects on ecosystems and biota. As it biomagnifies in the food chain, its presence in edible fish poses a high risk to human health. Herein, total Hg (THg) content was quantified in 2018–2019 using thermal decomposition amalgamation atomic absorption spectrometry in muscle tissue of red mullet (Mullus barbatus), a commercially important species throughout the Adriatic Sea (Central Mediterranean Sea). Specimens were grouped into 16 pools based on sex, reproductive stages, and sampling area. The overall mean value of THg content was 0.20 ± 0.15 mg kg⁻¹ in terms of wet weight. THg levels in males and females showed no statistically significant differences, whereas specimens that were captured in open sea showed a higher THg content than coastal samples. Statistically significant differences between THg content and the reproductive stages of fish were found in females. However, neither lipid content nor fish length were statistically correlated with THg content. The analyzed specimens were considered to be safe food according to EU directives, but it is necessary to exercise caution and further investigate Italian people in the 0–18 age group, because they were found to be exposed to a higher dose of methylmercury than the safety threshold set by the EFSA.