## 4 Discussion
This value is higher than those reported in most other studies in different Mediterranean areas [16, 17, 18, 19]. Regarding the estimated parameters of the von Bertalanffy growth curves, a low estimate of K, together with a high L\({}_{\infty}\) in both areas, indicates that the black scorpionfish is a slow-growing and long-lived species. Growth curves constructed for fish from the Split area and Pag Island area revealed a significantly different age structure for _S. porcus_ in the Adriatic. In the Pag Island area, we found only one individual older than 8 years. In addition, almost 59% of the catch in the Pag Island area comprised the first four age classes (0\({}^{+}\) to 4\({}^{+}\)), whereas in the Split areathe same age classes made up more than 70% of the catch. The large variation in results also can be observed on a larger spatial scale, when comparing the growth parameters for the black scorpionfish obtained by different authors [10; 15]. By calculating the growth performance index, our results showed somewhat slower growth rates than those reported in other areas [15; 19; 44; 45]. These differences throughout the Mediterranean indicated population separation and may be a consequence of different (i) latitudes, (ii) environmental conditions, (iii) size distribution of sampled fish (heterogeneity of the sample), and (iv) fishing pressures. The substantial length range of the black scorpionfish over both investigated coastal areas in the Adriatic demonstrates that environmental conditions in these two areas are highly favorable for sustaining populations of this species and that their requisite food resources are abundant. Regardless, _S. porcus_ showed significant spatial structuring, as observed length, dietary, and age compositions were heterogeneous among the two areas. Contributions of the individual prey species seemed to benefit these scorpionfish populations in terms of maximum size and growth performance. Fish from the Pag Island area ingested a greater diversity of prey types, had a specific dietary composition, reached the highest TL, and showed a higher growth rate. The growth rate depends on a variety of local abiotic factors such as temperature, levels of dissolved oxygen and ammonia, salinity, photoperiod, food availability, and quality [21], and we are aware that the latter is just one of them. Most studies have focused on temperature, due to its known effect on fish metabolism, and have shown that the growth rate of a species is generally lower at higher and cooler latitudes than at lower and warmer latitudes [46; 47; 48]. Additional research should, therefore, identify all variables that are most likely to influence _S. porcus_ populations in different areas and should quantify their relative influence on fish biology, specifically growth rates. However, our results highlight the need to understand the relative contributions of such area-specific data. The importance of considering the spatial stratification of the _S. porcus_ population and the variability of its biological traits is emphasized. As information on spatial ecology is necessary for effective management and conservation of fish populations, we recommend managing the black scorpionfish in the Mediterranean as separate management units. At the same time, analysis of long-term data showed that the Adriatic population of _S. porcus_ did not go through profound changes [7], so the results of this study imply that the observed variability in traits reflects adaptations of this species to different conditions that have enabled it to successfully solve ecological problems. Conceptualization, J.F. and S.M.-S.; methodology, J.F. and S.M.-S.; software, J.F. ; validation, J.F. and S.M.-S.; formal analysis, J.F. ; investigation, J.F. ; resources, J.F. and S.M.-S.; data curation, J.F. and S.M.-S.; writing--original draft preparation, J.F. ; writing--review and editing, J.F. and S.M.-S.; visualization, J.F. ; supervision, S.M.-S. All authors have read and agreed to the published version of the manuscript.