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The Mediterranean Large Elasmobranchs Monitoring (MEDLEM) database contains over 3000 records (more than 4000 individuals) of large elasmobranch species from 20 different countries around the Mediterranean and Black seas, observed from 1666 to 2017. The main species included in the archive are the devil fish (1 813 individuals), the basking shark (939 individuals), the blue shark (585 individuals) and the great white shark (337 individuals).In the last decades other species such as the shortfin mako (166 individuals), the spiny butterfly ray (138) and the thresher shark (174 individuals) were reported with an increasing frequency. This was possibly due to an increased public awareness on the conservation status of sharks, and a consequent development of new monitoring programmes. MEDLEM does not have a homogeneous reporting coverage throughout the Mediterranean and Black seas and it should be considered as a database of observed species presence. Scientific monitoring efforts in the south-eastern Mediterranean and Black seas are generally lower than in the northern sectors and the absence in our database of some species does not imply their actual absence in these regions. Some considerations are made on the frequency and spatial distribution of records, size structure of the observed individuals for selected species, general area coverage and species involved as by-catch by fishing gear.
The growth of Mullus barbatus has been widely studied using different methods, but no previous study has focused on age validation. The uncertainty in estimating the age of the red mullet by otolith reading is linked to the number of false-growth increments laid down before the annulus. The capture of red mullets in the early life stage allowed us to estimate their size at the metamorphosis from the pelagic to the demersal phase. The comparison between the metamorphosis size and the back-calculated length of the first growth increment clarified the position of the false growth increment on the otolith. Moreover, the analyses of the otolith marginal increments in adult and juvenile specimens allowed us to define the deposition patterns of their annuli. The modal components of the length–frequency distribution analysis (LFDA) were identified in the winter survey (ELEFAN and Bhattacharya methods), and they did not show significant differences from the length back-calculation of the annuli. Moreover, no significant differences were found between the growth curves calculated by otolith reading (back-calculation and direct otolith reading) and the LFDA. The agreement between the length–frequency results and the otolith age estimation either corroborated or indirectly validated the growth pattern estimated in the otoliths of the red mullet, mainly when the direct validation methods (e.g. mark-recapture, captivity, radiochemical) were difficult to implement, like the case of this species. The comparison of the results of the present work to previous Mediterranean studies showed agreement with the slow growth pattern.
The main aim of the present study is to increase the knowledge on the seasonal dynamics of the set gears used by Adriatic small-scale fisheries (SSFs) through the collation of data (landings, fishing effort, composition of catches, length-frequency distributions of target species and economic value of landings) on target species,. The study focused on the three set gears mainly used in the basin: gillnets, trammel nets and traps. The results confirmed that SSFs are diverse, complex and dynamic, representing an economic and social engine and providing seafood and employment to local economies. In the Adriatic Sea, SSFs exploit coastal fishing grounds where the seasonal fluctuations of the physical and chemical parameters of the water column strongly influence the occurrence of the different species. Because of this, many different types of set gears are currently used to catch a pool of target species over the year. Fishermen use more than one set gear during the year and tend to increase the fishing effort when the target species concentrate inside the coastal areas during the recruitment or the spawning season. Accordingly, landings reached the highest values during such periods and often include a large portion of juveniles and/or spawners. The study highlighted that the lack of appropriate data and complete statistics is still one of the main constraints for most of the Adriatic coastal countries, as few countries have in place routinely monitoring programs while others are dealing mostly with estimates. These gaps often have the effect of marginalizing and undervaluing the real role of SSFs in a Blue Growth process.
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