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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.

Within this paper, reproduction traits of the Adriatic population European hake, Merluccius merluccius (Linnaeus, 1758), were investigated. Specimens of the target species were monthly collected (N=1173) during 2019 along the eastern Adriatic Sea with commercial bottom trawlers. Overall, European hake total body length varied between 15.5 and 49.5 cm (mean±SD=27.5±5.0 cm) and domination of females was noted in larger length classes (TL>31.0 cm). The sexual ratio of all specimens was m/f=0.64; male prevalence was established over the year, except during the spawning peaks (December, June) when the sex ratio was in favour of the females. According to European hake’s maturity stages, gonad weights, gonadosomatic indexes and histological analysis of the gonad tissues, this species in Adriatic spawn twice in one year; the spawning period was from December to February, while second smaller signs of spawning were observed at the beginning of the summer, in June. 50% of the European hake male and female specimens sexually matured at 20.7 cm and 22.4 cm of total length, respectively., U okviru ovog rada je istražena reproduktivna biologija jadranske populacije oslića, Merluccius merluccius (Linnaeus, 1758). Uzorci istraživane vrste su prikupljeni iz uzoraka lovina ostvarenih komercijalnom pridnenom mrežom koćom s područja istočnog Jadrana (Hrvatsko ribolovno more) jednom mjesečno (N = 1173) tijekom 2019. godine. Raspon totalnih dužina tijela oslića se kretao između u rasponu od 15,5 cm do 49,5 cm (srednja vrijednost ± SD = 27,5 ± 5,0 cm) te je pri većim dužinskim razredima zabilježena dominacija ženki (TL> 31,0 cm). Omjer spolova (m/ž) je iznosio 0,64; prevalencija mužjaka je utvrđena tijekom čitave godine izuzev razdoblja mrijesta (prosinac, lipanj) kada je omjer spolova bio u korist ženki. Analizom stadija zrelosti, mase gonada, gonadosomatskog indeksa te histoloških preparata tkiva spolnih žlijezda utvrđeno je da se ova vrsta u Jadranu mrijesti dva puta u jednoj godini; utvrđeno je razdoblje mrijesta od prosinca do veljače, dok je drugo razdoblje mrijesta nešto slabijeg intenziteta utvrđeno početkom ljeta, točnije u lipnju. Prva spolna zrelost svih analiziranih jedinki oslića je nastupila pri totalnoj dužini tijela od 20,7 cm za mužjake odnosno 22,4 cm za ženke.

The uncertainty in age estimation by otolith reading may be at the root of the large variability in red mullet (Mullus barbatus) growth models in the Mediterranean. In the MEDITS survey, red mullet age data are produced following the same sampling protocol and otolith reading methodology. However, ageing is assigned using different interpretation schemes, including variations in theoretical birthdate and number of false rings considered, in addition to differences in the experience level of readers. The present work analysed the influence of these variations and the geographical location of sampling on red mullet ageing using a multivariate approach (principal component analysis). Reader experience was the most important parameter correlated with the variability. The number of rings considered false showed a significant effect on the variability in the first age groups but had less influence on the older ones. The effect of the theoretical birthdate was low in all age groups. Geographical location had a significant influence, with longitude showing greater effects than latitude. In light of these results, workshops, exchanges and the adoption of a common ageing protocol based on age validation studies are considered fundamental tools for improving precision in red mullet ageing.