Vafidis D’s research while affiliated with University of Thessaly and other places

Small-scale fisheries (SSF) constitute an important part of the fishing industry in Greece and the Mediterranean and are characterized by high heterogeneity and a multitude of specificities. The socioeconomic characteristics of the SSF fleet operating in south Evoikos were assessed using exploratory data analysis and supervised machine learning algorithms. Data were collected during winter-spring of 2023 through personal interviews using a structured questionnaire from 51 professional fishermen. Results exhibited an ageing workforce (60 years old mean age) with low education (74% primary school education), a similarly ageing fleet (mean 26 years old) and a fishing activity year-round. An interesting finding of the present study was the admission from two thirds of the interviewed fishermen that they regularly fish in the proximity of floating cage aquaculture farms. The best performed model (Gradient Boosting) indicated that the main reasons that influence the SSFs sector in the south Evoikos region in the choice of the fishing grounds is primarily vessel total length, followed by the fisherman's experience and port of embarkation.

Hematological properties of M. merluccius, a widespread bottom-dwelling species in the Mediterranean Sea, highly sought-after from the commercial fishery captured using a traditional Greek commercial bottom trawl from Toroneos gulf were estimated. Blood samples were retrieved from the tail vein of 40 adult individuals captured from variable depths and trawl durations. Hematological properties measured by an automated hematology analyzer included red blood cells (RBC), white blood cells (WBC), hemoglobin concentration (Hb), hematocrit (Ht) and thrombocytes (TC). Significant correlations were observed among most hematological properties. Significant differences were observed in RBC, Hb and Ht among the present study and values from wild caught European hake from Argentina and Denmark. Trawling depth and duration were both factors significantly affecting RBC, WBC, HB, and Ht with no significant effect on TC. Individuals captured from 80-meter average depth and 30 min trawl duration exhibited significantly higher values. Assessing the state of fish populations faces hurdles due to the lack of reliable references in their natural habitat. Hematology analysis stands out as a cost-effective and practical method extensively employed to gauge the physiological and health status of fish. However, there is a scarcity of comprehensive data regarding the hematological parameters of M. merluccius.

Fishing tourism is an eco-friendly and environmentally sustainable touristic activity exhibiting a growing development in several European coastal regions as an innovative product. The potential of fishing tourism as an alternative source of income for the small-scale fisheries sector is highlighted for Magnesia region. The present study describes the practices currently applied, highlights the impediments for further growth and proposes measures for its development in the region.

Aquaculture by-products can be compromised an important liming material of increasing soil pH and soil fertility. The aim of this research was to assess the effect of mussel shells on soil pH, on organic matter and on soil nutrients. In this study a pot experiment was carried out at the De-partment of Ichthyology and Aquatic Environment (University of Thessaly, Greece). A acidic soil (pH 4.26) amended with 6 different proportions of mussel shell (0.0, 0.1, 0.3, 0.5, 1, 3 and 6%) in two different grain sizes (Fine powder (>1 mm) and Coarse powder (1-2 mm)), resulting in 13 treatments. According to the results, it was observed that pH, organic matter, Available P and Exchangeable K increased. Specifically, the highest pH values observed at 6% rate. Available P and Exchangeable K achieved the highest content at 6% Fine powder treatment, 46.2 and 190.1 mg kg-1, respectively. Similarly, organic matter had the highest value in 6% Fine powder pots (2.27%). Moreover, Total N concentration varied from 0.11 to 0.14 but no statistically significant different was noticed between the treatments. In conclusion, mussel shells can compose a promising liming material in the agriculture section.

It is well documented that population structure needs to be defined for fishery management purposes. However, studies are scarce and information about finer scale population structure, which is important for stock assessments and fishery management, is largely lacking. In the present study the population genetics of the European hake (Merluccius merluccius, L.) was evaluated using the Cytochrome Oxidase subunit I (COI) MtDNA. Results show that the species in the limit of its distribution is dominated by the same unique haplotype, suggesting a low heterozygosity and possibly a vulnerable population with respect to fitness. On the other hand, in the southern Aegean there is a unique haplotype, suggesting local adaptation of the species. Fst pairwise differences suggest in general a differentiation within the Mediterranean basin. Keywords: population genetics, COI, Mediterranean, European hake

The content of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn as the whole-body burden and the content of Cd and Pb in muscle tissue of Parapenaeus longirostris, were evaluated in shrimp collected from the Pagasitikos Gulf, Greece. The whole-body burden of Fe was 102 ± 39, Mn 71 ± 23, As 64 ± 33, Zn 62 ± 8, Cu 34 ± 16, Ni 4.6 ± 2.9, Cr 1.01 ± 0.39, Cd 0.93 ± 0.33 and Pb 0.88 ± 0.47 ppm wet weight. Muscle tissue content for Cd was 0.47 ± 0.08 and for Pb 0.31 ± 0.06 ppm wet weight. The estimation of weekly intakes and target hazard quotients for the potentially toxic elements Cd and Pb revealed that rose shrimp from Pagasitikos Gulf could be considered safe for human consumption, probably with a general advisory to avoid the consumption of anything other than the muscle tissue.

This work examines the spatial and temporal variability of sea surface temperature (SST) in a marine protected area (MPA), using remotely sensed data. The National Marine Park of Alonissos, Northern Sporades, was selected as a study area. Satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer), NASA's Terra satellite, were used, covering a period of twenty years. Both day and night monthly SST satellite images were examined and the slope of temperature was extracted for each pixel of the study area. The results showed that there is an increasing trend in SST throughout the study area with local variations.