Books by George KATSELIS
Lagoon fisheries’ resources in Hellas
Papers by George KATSELIS
Information
This study explores the design and capabilities of a Geographic Information System (GIS) incorpor... more This study explores the design and capabilities of a Geographic Information System (GIS) incorporated with an expert knowledge system, tailored for tracking and monitoring the spread of dangerous diseases across a collection of fish farms. Specifically targeting the aquacultural regions of Greece, the system captures geographical and climatic data pertinent to these farms. A feature of this system is its ability to calculate disease transmission intervals between individual cages and broader fish farm entities, providing crucial insights into the spread dynamics. These data then act as an entry point to our expert system. To enhance the predictive precision, we employed various machine learning strategies, ultimately focusing on a reinforcement learning (RL) environment. This RL framework, enhanced by the Multi-Armed Bandit (MAB) technique, stands out as a powerful mechanism for effectively managing the flow of virus transmissions within farms. Empirical tests highlight the efficien...
Agricultural Economics Review, 2016
The "avgotaracho Messologgiou" PDO is a traditional product with protected designation of origin ... more The "avgotaracho Messologgiou" PDO is a traditional product with protected designation of origin of which quality control based on the experience of the producers. This is salted, semi-dried whole ovaries of Mugil cephalus that caught during species spawning seaward migration in the barrier traps of the well-defined lagoon system of Mesolonghi-Etolikon. In the present study a description of the processing stages of the above product was conducted. Results showed that fresh ovaries drying on ambient air according to climatic conditions for approximately 8 days (mean 7.7 days), up to a weight reduction of about 33.63% (SD: 4.3%) of the initial weight. Thereafter, dried ovaries pass through the waxed-coating stage in which dried weight increased about 20.1% (SD: 4.3%). Although quality control is based on the experience of the producers, processing stages were characterized by high accuracy. The effect of climatic conditions on the processing stages was also analysed and discussed. The certification of the product as PDO would safeguard the traditional character of the product against the imports of frozen roes of M. cephalus originating by other regions due to the global expansion of the species.
Diversity
In the present study, the biology of the pumpkinseed Lepomis gibbosus in the artificial lake of A... more In the present study, the biology of the pumpkinseed Lepomis gibbosus in the artificial lake of Aoos, located in northwestern Greece, was investigated. The samplings of the pumpkinseed were conducted from the shore using a portable electrofishing device over a 4-month period (July 2021–October 2021). A total of 581 specimens were caught, with an average length of 62 mm. The sex ratio of female to male was estimated to be 1.0:1.7, and the percentage of mature specimens was estimated for all of the months to be above 52%, matching the highest percentage in July (57.4%). The b value of the length–weight relationship ranged from 3.16 in September to 3.31 in July. The value of the L∞ and K was estimated to be equal to 119 mm and 0.36 years−1, respectively, and the value of φ′ was equal to 3.707. The total mortality was estimated to be equal to 1.63 ± 0.48 y−1 (R2 = 0.96), and the natural and fishing mortalities were 0.83 and 0.80, respectively. The maximum age was 6 years, and the theore...
Animals
The lack of historical data on shark presence, distribution, and status in the Eastern Mediterran... more The lack of historical data on shark presence, distribution, and status in the Eastern Mediterranean undermines efforts to manage and protect their populations. An exhaustive review of anecdotal references related to shark presence during the early and development phase of Greek fisheries (1883–1983) was conducted. In the early-20th century (1912), the first sighting of the presence of a dead shark was reported in the Ionian Sea. Later on, the presence of sharks gradually increased up to 1969, with most records being more frequent for the Aegean Sea, whereas the number of sharks being sighted declined leading up to the middle of 1980s. The increase in shark attacks during the mid-20th century led to a calling for culling of sharks in co-operation with the competent authorities promoting the permission to hunt sharks with firearms and offering rewards for killed individuals. A high number of these observations potentially resulted from shark attacks on people, whereas this is not cur...
Journal of Marine Science and Engineering
The Greek marine aquaculture has a leading role in the Mediterranean mariculture industry, mainly... more The Greek marine aquaculture has a leading role in the Mediterranean mariculture industry, mainly in the export sector and its prominent contribution to the country’s economy. In the present study, the spatial distribution of Greek finfish farming activity and its potential impact zones on the marine environment were estimated and mapped. The Greek coastline was scanned via Google Earth satellite images for the period of June 2016 to May 2017, with 433 fish farm cage arrays being detected. For each cage array, the zones at different distances corresponding to various type of impacts were mapped by means of GIS technologies. Seventy-five spatial clusters of cage arrays (sc) were revealed, including cage arrays with shown connectivity. As per the findings, Greek marine fish farming activity shows a high level of spatial aggregation but with a relative moderate intensity of impacts due to legal constraints, which play a crucial role in controlling the spatial distribution of activity a...
Journal of Marine Science and Engineering
The present study investigates through an integrated survey, for the first time in Greek shellfis... more The present study investigates through an integrated survey, for the first time in Greek shellfish market, the marketing distribution towards a new edible shellfish product that of the non-indigenous pearl oyster Pinctada imbricata radiata. The survey conducted through personal interviews on sector entrepreneurs/staff of the supply (i.e., shellfish producers, wholesalers, fishmongers, owners of restaurants). Internet-based quantitative research was also conducted to explore the market supply of the pearl oyster covering all nine regional units of Greece. The market for pearl oyster seems to be there as a substitute of the major commercial species in seasons of shortages. There is a specimen mislabeling throughout Greece, thus, extraction of significant information about the market supply of pearl oyster is deficient. Further knowledge on the bivalve shellfish value chain is needed, to define how the wild and the farmed species (mussels) interact in the market and in the distribution...
Fishes
Accurate checklists of species are essential for evaluating their conservation status and for und... more Accurate checklists of species are essential for evaluating their conservation status and for understanding more about their distribution, biology and ecology and, therefore, the first step in order to effectively protect them. According to the existing literature, the Greek seas are rich in chondrichthyan biodiversity and herein, we update the most recent chondrichthyan checklist for the country regarding the species that are present in the Greek waters, correct unvalidated miscellaneous sightings and observations and provide guidelines about future research to improve their conservation. In total, 330 sources were collected from which 276 were used for further analysis, resulting in 1485 records of 67 species, among which 61 are confirmed by experts, including 34 sharks, 26 batoids and one chimaera. We are further listing six species as “Questionable/Not Confirmed”.
Journal of Marine Science and Engineering
Greece exhibits the lowest seafood per capita consumption amongst European Mediterranean countrie... more Greece exhibits the lowest seafood per capita consumption amongst European Mediterranean countries, and the investigation of consumer attitudes to new seafood products would bridge the gap among producers and consumers by promoting the vertical integration of the supply chain. However, limited information exists about consumer preferences for bivalves in the Mediterranean and for wild bivalves in particular. The present study aims to investigate, for the first time, consumers’ attitudes towards the purchase and consumption of bivalves, and more specifically, towards the edible pearl oyster Pinctada imbricata radiata, in the Greek shellfish market. Adult participants from the entire country completed a questionnaire covering the basic marketing aspects of bivalve and pearl oyster consumption, such as choice, purchase, reasons for consuming bivalves, confidence in product’s hygiene certification, media influence, etc. Data analysis included uni- and multi-variate statistics to examine...
International Journal of Fisheries and Aquaculture, Jan 31, 2011
The population structure of freshwater crab of Paratelphusa masoniana (Henderson) was studied in ... more The population structure of freshwater crab of Paratelphusa masoniana (Henderson) was studied in the lower reaches of river Chenab in J&K, India. Crabs were randomnly sampled on monthly basis from June 2010-May 2011, a total of 581 crabs were obtained of which 283 (48.37%) were males and 302 (51.62%) were females. The overall sex ratio was found to be 1:1.07 indicating that females were numerically more in compared to males. However sex ratio never remain constant but exhibited fluctuation pattern throughout year especially in the month of June-July and December-January when it was recorded to be almost less than unity (1:0.40, 1,1:0.6 and 1:0.55 respectively). The present population represents non normal size frequency distribution with male reaching greater size (5-6 cm cw) than females (4-5 cm cw).
he "avgotaracho Messologgiou" PDO is a traditional product with protected des- ignation... more he "avgotaracho Messologgiou" PDO is a traditional product with protected des- ignation of origin of which quality control based on the experience of the producers. This is salted, semi-dried whole ovaries of Mugil cephalus that caught during species spawning seaward migration in the barrier traps of the well-defined lagoon system of Mesolonghi-Etolikon. In the present study a description of the processing stages of the above product was conducted. Results showed t hat fresh ovaries drying on ambient air according to climatic conditions for approximately 8 days (mean 7.7 days), up to a weight reduction of about 33.63% (SD: 4.3%) of the initial weight. Thereafter, dried ovaries pass through the waxed-coating stage in which dried weight increased about 20.1% (SD: 4.3%). Although quality control is based on the experience of the produc- ers, processing stages were characterized by high accuracy. The effect of climatic con- ditions on the processing stages was also analysed an...
Multi-disciplinary approach of reported and unreported fisheries in a new established MPA: The case of Cavo Greco, Cyprus
Regional Studies in Marine Science, 2021
Abstract In fisheries management it is essential to evaluate the effectiveness of marine protecte... more Abstract In fisheries management it is essential to evaluate the effectiveness of marine protected areas (MPAs), understand the shortcomings and limitations of MPAs and propose measures to improve their functioning. Information provided by local fishers and monitoring by the managers were evaluated to depict insights and identify deficiencies in the fishery management of a newly established MPA in the Eastern Mediterranean Sea (Cavo Greco). The study revealed a paradox; even though the majority of the professional and recreational fishers were aware of the MPA, high illegal fishing activity was mentioned within the MPA zones. Based on managers’ and fishers’ statements this was due to the lack of: (a) information about the benefits of a MPA, (b) of enforcement on the professional and recreational fishery, (c) limited fisher’s compliance with the rules and (d) distant mooring ports that make the patrolling of the fishing activity difficult. Species composition of the fishery catches was diversified due to the large contribution in the landings by non-indigenous species, especially the rabbitfish Siganus spp. which constituted from 32.1% to 53.8%, depending on season. Findings could be incorporated in the decision-making process towards the improvement of the implementation of the revisited Common Fisheries Policy.
Mapping fisheries hot-spot and high-violated fishing areas in professional and recreational small-scale fisheries
Aquaculture and Fisheries, 2019
Abstract The present study deals with the monitoring for a real implementation of management poli... more Abstract The present study deals with the monitoring for a real implementation of management policies in marine environments and the potential conflicts between professional and recreational fishery in the coastal areas of the Mediterranean Sea. A comprehensive database of fishing effort and fisheries infringements from professional small-scale and recreational fisheries was screened to identify hotspots areas of fishing pressure in the coastal zones of Ionian Sea. Mapping points showed that the number of the recorded infringements conducted both by professional and recreational fishers are too low (1 and 6 recorded infringements per 104 km2 of vessel days per year) and that fishing effort, and subsequently the recorded infringements, are not evenly distributed but concentrated on specific fishing grounds. These revealed high-risk areas prone to illegal fishing activities and are implying problems in the implementation of the fisheries regulations rather than a low delinquency of the fishers to comply with the rules. Findings represents a step forward in applying tracking technology to the surveillance of small-scale fishery and are crucial towards the specification of the critical zones for setting an efficient control system.
Acta Adriatica, 2017
A total of 346 live animals of the endangered species fan mussel Pinna nobilis (Linnaeus 1758) we... more A total of 346 live animals of the endangered species fan mussel Pinna nobilis (Linnaeus 1758) were recorded in situ in the shallow water zone (<2m) within two sites of the marine protected area “Natura 2000” of Maliakos Gulf (Central Hellas). Our results showed that the recorded length (from 11.89 to 72.51 cm) of the fan mussels corresponds to ages that cover the majority of the species life time. Population densities were comparable to the higher values recorded previously in the Mediterranean Sea. The spatial distribution of species was clumped. Estimated total mortality was close to estimated natural mortality indicating that fishing activity does not significantly affect the population density and mortality of fan mussel in the study area. Population densities were related to sediment type, the buried length of animals was related to both sediment type and sea grass leaves size.
Ocean & Coastal Management, 2017
Minimizing illegal fishing is of paramount importance for fisheries sustainability. The present s... more Minimizing illegal fishing is of paramount importance for fisheries sustainability. The present study focused on the fisheries infringements through the analysis of the official records in one of the largest Mediterranean lagoons, Mesolonghi-Etolikon, and the analysis of questionnaires answered by local fishermen to determine the true effectiveness of the control efforts. This double analysis represents a valuable case study for determining illegal fisheries practices, status of control, and efficacy of regulations. Results exhibited that: (a) the high contribution of the recorded infringements was due to absence of fishermen/vessel licenses, (b) fines are not proportionate with the type of illegal activity, and (c) the number of the recorded infringements represented a very small percentage of the estimated number of fishing days conducted by both professional fishermen and people not having fishing/vessel license. Findings indicated a situation with great presence of illegality that might completely weak any possibility for assessing the status of fisheries and resources and seriously hamper any definition of thresholds useful for sustainable management. Solutions are discussed especially in the light of revision of regulations and of transparency in the decision-making process.
Marine pollution bulletin, Jan 24, 2017
The native distribution of the blue crab Callinectes sapidus in the western Atlantic extends from... more The native distribution of the blue crab Callinectes sapidus in the western Atlantic extends from Nova Scotia to Argentina. Introduced to Europe at the beginning of the 20th century, it is currently recorded almost ubiquitously in the Mediterranean and in the Black Sea. An overview of the occurrence, abundance, and ecological impact of the species in southern European waters is provided; additionally, we present a pragmatic assessment of its management scenarios, explicitly considering the dual nature of C. sapidus as both an invasive species and a fishery resource. We emphasise that the ongoing expansion of C. sapidus in the region may represent a stimulating challenge for the identification and implementation of future strategies in the management of invasive crustaceans. The impact of the invader could be converted into an enhancement of the services delivered by southern European coastal ecosystems, while mitigation costs could be transformed into profits for local populations.
Sex-specific daily spawning seaward migration of striped mullet Mugil cephalus in a coastal lagoon
Journal of Fish Biology, 2015
The sex-specific daily spawning seaward migration of striped mullet Mugil cephalus was analysed i... more The sex-specific daily spawning seaward migration of striped mullet Mugil cephalus was analysed in Palaiopotamos Lagoon (western Greek coast, eastern Mediterranean Sea) in an 86 day time series. The data set included the daily number of M. cephalus catches in barrier traps, as well as a time series of some weather variables. The analysis revealed an important linkage of the daily migration rate as well as a sex-specific response of the species to the lunar cycle and the short-term fluctuation of weather variables. The daily migration pattern of females was more persistent than that of males, indicating a possible female leadership role during the spawning migration. Multiregression models described quite accurately the sex-specific daily migration rates of the species, thus providing a potentially powerful tool regarding the lagoon fishery management of M. cephalus, especially in the context of climate change.
Estimation and reconstruction of shore-based recreational angling fisheries catches in the Greek Seas (1950-2010)
Investigation of Length-Weight Relationships for 10 commercial fish species as a possible trophic state index of Coastal Lagoons
Mediterranean Marine Science, 2013
The recognition and identification of the two species of Spicara genus (Spicara flexuosa, picarel... more The recognition and identification of the two species of Spicara genus (Spicara flexuosa, picarel and Spicara maena, blotched picarel) is difficult, due to a systematic confusion until now. In the present work a number of external morphometric features (ten body ratios) are evaluated for their diagnostic possibilities. According to Principal Component Analysis results, the body ratios head length to standard length, head height to head length and the ratios of two body heights, indicated that these characters were not related to the maturity stage of the species. The discriminant analysis based on the above body ratios, indicated rather high level of discrimination (83.2%) of the examined samples in two species. The results are discussed, and possibilities of improvement in the identification methodology for the two species are proposed.
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Books by George KATSELIS
Papers by George KATSELIS