Books by Athanassios Tsikliras
Papers by Athanassios Tsikliras
Applied Sciences
In this work a fish species distribution model (SDM) was developed, by merging species occurrence... more In this work a fish species distribution model (SDM) was developed, by merging species occurrence data with environmental layers, with the scope to produce high resolution habitability maps for the whole Mediterranean Sea. The final model is capable to predict the probability of occurrence of each fish species at any location in the Mediterranean Sea. Eight pelagic, commercial fish species were selected for this study namely Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Scomber colias, Scomber scombrus, Spicara smaris, Thunnus thynnus and Xiphias gladius. The SDM environmental predictors were obtained from the databases of Copernicus Marine Environmental Service (CMEMS) and the European Marine Observation and Data Network (EMODnet). The probabilities of fish occurrence data in low resolution and with several gaps were obtained from Aquamaps (FAO Fishbase). Data pre-processing involved feature engineering to construct 6830 features, representing the distribution of s...
Seafood mislabeling in Greek market using DNA barcoding
Food Control
Abstract The mislabeling of seafood products is a worldwide observed issue even though labeling r... more Abstract The mislabeling of seafood products is a worldwide observed issue even though labeling regulations have been established (either at local or European/International level). Various molecular methods have been developed for fish species identification and detection of fraud, with DNA barcoding being the most popular and accurate one. Here, we present the first large-scale analysis aimed at assessing the fish mislabeling rate in Greece, by amplifying a fragment of approximately 655bp of the COI gene in 285 fish products collected from multiple markets in Greece through a monitoring program of the Hellenic Food Authority (EFET) over a time span of 4 years. This study initiated in 2015 under a European Commission Recommendation on a coordinated control plan with a view to establishing the prevalence of fraudulent practices in the marketing of certain foods and was further supported by EFET for another 3 years in order to monitor the Greek market. Sequencing and species attribution was successful in 92.3% of the samples. In 12.9% of these (34 cases), discrepancies were detected between the declared and the identified species and therefore the products were characterized as mislabeled. This rate is low, compared to other studies in Greece and other regions of the Mediterranean Sea (e.g. Italy) and worldwide (e.g. Canada). On the other hand, it remains higher than the average global substitution rate of 8%, reported in a recent meta-analysis and the European rate of 6% detected during the EU coordinated control program in 2015. Flatfishes (order Pleuronectiformes) presented the highest mislabeling rate (28.3%) followed by gadiforms (order Gadiformes) with 13.7%. Although, in some cases the substitution can be unintentional due to similar morphological characteristics and geographical distribution among species, in 55.7% of the mislabeled samples the substituted species is of lower quality resulting inevitably also to an economic profit. Our results support the need for continuous and well-documented monitoring of Greek and European markets.
Age and Growth of Mediterranean Marine Fishes
Biolog�a reproductiva de la alacha ( Sardinella aurita ) en el Mediterr�neo NE
Scientia Marina, 2006
The relationship between market price and body length for finfishes from the Greek Seas
Acta Adriatica, Jun 2, 2011
or even to habitat characteristics (LA MESA et al., 2006). The groupings of co-occurring larval f... more or even to habitat characteristics (LA MESA et al., 2006). The groupings of co-occurring larval fish species often exhibit temporal and spatial variability reflecting behavioral adaptations, variable survival rates and response to external stimuli such as interactions between hydrodynamic processes (BAKUN, 2006). The study of the summer community structure of Mediterranean marine fish is important
Reproductive biology of the marbled goby, Pomatoschistus marmoratus (Pisces, Gobiidae), in a northern Aegean estuarine system (Greece)
Folia Zoologica Praha, 2009
Page 1. 447 *Corresponding author Folia Zool. 58(4): 447456 (2009) Reproductive biology of the... more Page 1. 447 *Corresponding author Folia Zool. 58(4): 447456 (2009) Reproductive biology of the marbled goby, Pomatoschistus marmoratus (Pisces, Gobiidae), in a northern Aegean estuarine system (Greece) Emmanuil T. KOUTRAKIS1 and Athanassios C. TSIKLIRAS2 ...
Reconstruction of Greek Marine Fisheries Landings: National Versus Fao Statistics 1
ABSTRACT We reconstructed Greek fisheries catches from 1950-2003. The landings data recorded by t... more ABSTRACT We reconstructed Greek fisheries catches from 1950-2003. The landings data recorded by the National Statistical Service of Greece have been compared with those reported by FAO for 1964-2003. For 1969-2003 we also reconstructed landings derived from rowing boats and coastal boats with engine power <19HP, which are not reported by either dataset. We disaggregated these landings by taxon, based on recent reports of the mean catch per unit of effort of all species caught by different small-scale gears. This allowed estimation of the total Greek marine fisheries landings and comparison with the corresponding FAO data. The reconstructed total landings indicated an average underestimation by 35% (range: 10-65%) of Greek landings based on the reported landings as presented by FAO on behalf of Greece. Except for the taxonomic differences (e.g., the case of Sardinella aurita) and the different taxonomic resolution (e.g., the case of Spicara spp.), which accounted for several discrepancies between the two datasets, the two datasets also differed for most taxa over the period 1964-1969 and for the years 1997 (FAO landings are overreported) and 1998 (FAO landings are underreported). With respect to catches by individual taxa through time, the two datasets generally agreed for the small pelagics and, to a lesser extent, for demersal taxa. The taxa which accounted for the larger and more consistent difference between the two datasets were the large pelagics (swordfish, bluefin tuna and other tuna-like fishes), which were commonly underreported by the national dataset by a factor of 2 for the years following 1990.
Scientific Impact of Fishbase: A Citation Analysis
Scientia Marina, 2005
The round sardinella, Sardinella aurita Valenciennes, 1847, was sampled monthly from commercial p... more The round sardinella, Sardinella aurita Valenciennes, 1847, was sampled monthly from commercial purseseine vessels in Kavala Gulf (northern Aegean Sea, Greece) for two complete year cycles (September 2000-August 2002). Its maximum total length and age were 248 mm and 5 years respectively. The length-weight relationship was W=0.0062TL 3.064 for males and W=0.0059TL 3.084 for females. The marginal increment analysis on scales (n=1352) confirmed annulus formation during February-March, which coincided with the lowest sea surface temperature prevailing in the study area. The marginal increment ratio for ages 1, 2 and 3 was positively correlated with sea surface temperature (all r>0.4, P<0.05). The parameters of the von Bertalanffy growth equation were: L ∞ =248.678 mm, K=0.509 yr-1 and t 0 =-0.881 yr. The comparison of growth parameters for round sardinella, using the auximetric plot, from Mediterranean and northwest African waters indicated different growth patterns between the two areas.
The mean trophic level (τ) of the Mediterranean farmed fishes (i.e. excluding crustaceans, cephal... more The mean trophic level (τ) of the Mediterranean farmed fishes (i.e. excluding crustaceans, cephalopods and bivalves) was estimated on a country basis for the period 1950-2004. Overall, τ increased from a mean value (±SD) of 2.68 (±0.044) for 1950-1959 to 3.21 (±0.031) for 2000-2004, thus confirming that the Mediterranean food webs, overall, are being farmed up. However, the pattern was not uniform across countries; France, Italy Turkey and Israel are farming progressively higher trophic level fishes, while the mean trophic level of farmed fish is declining in Greece, Egypt and Croatia. The overall trend toward farming farming up should be reversed, because it implies non-sustainable pressures on Mediterranean ecosystems.
The relationship between market price and body length for finfishes from the Greek Seas
Book review: Condition and Health Indicators of Exploited Marine Fishes
ABSTRACT Most articles on age/growth and reproductive biology of fishes usually include condi-tio... more ABSTRACT Most articles on age/growth and reproductive biology of fishes usually include condi-tion indices; however, condition and health indicators have been rather overlooked in fisheries ecology and this is particularly so with respect to their role in stock assessment and management. Lloret, Shulman and Love realized this omission and have addressed it through this book. Shulman and Love are world known for their accomplishments in fish ecology/physiology and biochemistry/biotechnology, respectively, and have pub-lished what can be considered to be a prequel to this book [Shulman, G. F &amp;amp; Love, R. M. (1999). The Biochemical Ecology of Marine Fishes. Advance in Marine Biology 36. London, U.K.: Academic Press]. Lloret is also very well known for his research on the condition and life-history of fishes. The book is structured into seven chapters and contains forewords by seven scien-tists, each of whom wrote a short comment. From these comments two points emerge: the gap in knowledge regarding the condition and health of fishes (even after the pub-lication of the book&amp;#39;s prequel) and the synthetic nature of this work that amalgamates biochemical and ecophysiological aspects into stock assessment and fisheries manage-ment. The first chapter describes the morphometric and organosomatic condition indicators; the second relates the physiological and biochemical indicators to fish metabolism; the third outlines the indicators of fish activity; the fourth, the largest one, deals with fish condition and life-history; the fifth connects environmental and anthropogenic factors to fish condition and the sixth the use of condition for measuring environmental status; finally, the seventh chapter emphasizes the use of fish condition indicators in stock assessment and fisheries management. The approach of each chapter being written in the form of a scientific article (with abstract and keywords; references within the text flow) aids the synthesis of knowl-edge and also facilitates reading. The authors collected and analysed a vast amount of references (about 900), some of which are very rare and hard to access, and have thus performed a particularly valuable task for fisheries scientists. With over 20% of the listed references written in Russian, the book makes a substantial part of the valuable Russian (former Soviet) literature available to more scientists. Each chapter contains a theoretical, a methodological and a practical part with real examples, often from the vast Russian literature. The condition and health indicators are exhaustively described at various levels of fish function and in that sense the book maybe considered a handbook. From the university lecturer&amp;#39;s point of view, it is also an outstanding text-book: it contains all theoretical information, which is well explained and appropriately 560 © 2014 The Fisheries Society of the British Isles
Ethics in Science and Environmental Politics, 2013
In this study, we used culturomics (i.e. analysis of large electronic datasets for the study of h... more In this study, we used culturomics (i.e. analysis of large electronic datasets for the study of human culture) in order to study the use of the names of various universities in the digitized corpus of English books. In particular, we used the Google Ngram viewer (available online: http://books.google.com/ngrams) to produce the frequencies of the names of 13 US, 5 UK and 4 Canadian universities in the English books and examined how these frequencies changed with time (1800 to 2008). We further used these frequencies to establish reputation rankings for these universities. Our results showed that Ngram is an easy-and-cheap-to-apply tool to approximate the reputation and 'intellectual' impact of universities over long time periods. Its reputationgenerating capability, at least for top universities, is not worse than the within-and betweensystem capabilities of commercial tools (i.e. QS, THE and THE World Reputation Rankings). Ngram can, thus, be promising at least for students (and their families), who make choices that are affected by rankings, providing them with additional benefits (e.g. perception of the historical impact of a university) when compared to the short-term, volatile annual commercial rankings.
Hydrobiologia, 2005
The ichtyofauna of the Porto-Lagos Lagoon in northern Greece was sampled over 17 months, using a ... more The ichtyofauna of the Porto-Lagos Lagoon in northern Greece was sampled over 17 months, using a bag-seine net, to investigate factors influencing species seasonal composition and abundance. Of the 35 resident, migrant and straggler species caught, representing 22 families, the most numerically dominant species were Atherina boyeri (46.4% of total catch), which today is the most economically important species, followed by Pomatoschistus marmoratus (28% of total catch) and Aphanius fasciatus (9.1% of total catch). Mugilidae and Sparidae were the most diverse families. According to various diversity indices, the lagoon’s ichthyofauna was found to be most diverse in May 1990; taxonomic spread however, as shown by the taxonomic distinctness index (Δ*), was lowest in July 1990, when the greatest monthly water temperature range was observed (13.5 °C). Overall fish relative abundance was positively correlated with the maximum monthly water temperature (r 2=0.32, p < 0.05). The NMDS and ...
The synchrony of pelagic fish population dynamics with climate variability may impose significant... more The synchrony of pelagic fish population dynamics with climate variability may impose significant alterations in their distribution and biomass, as well as catch composition, with potential effects on ecosystems and fisheries. This work examines the effect of the Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO) signals across the Mediterranean Sea sub-regions (western, central and eastern), with respect to small (European sardine Sardina pilchardus, European anchovy Engraulis encrasicolus, round sardinella Sardinella aurita and European sprat Sprattus sprattus) and medium (Atlantic mackerel Scomber scombrus, Atlantic chub mackerel Scomber japonicus, Atlantic horse mackerel Trachurus trachurus, Mediterranean horse mackerel Trachurus mediterraneus) pelagic fishes using various catch ratios and the mean temperature of the pelagic catch (MTpC) method for the period 1970-2014. The time until the pelagic fish communities react to the signals of the AMO and NAO, as revealed by the MTpC and catch ratios, varied among the Mediterranean sub-regions. The pelagic fishes of the central and eastern Mediterranean are those that responded most strongly to AMO variability, whereas those of the central and western Mediterranean also responded to the NAO. The effect of the NAO on pelagic fishes of the eastern Mediterranean was not significant.
This study presents a new method (LBB) for the analysis of length frequency data from commercial ... more This study presents a new method (LBB) for the analysis of length frequency data from commercial catches. LBB works for species that grow throughout their lives, such as most commercially-important fish and invertebrates, and requires no input in addition to length frequency data. It estimates asymptotic length, length at first capture, relative natural mortality, and relative fishing mortality. Standard fisheries equations can then be used to approximate current exploited biomass relative to unexploited biomass. In addition, these parameters allow the estimation of length at first capture that would maximize catch and biomass for a given fishing effort, and estimation of a proxy for the relative biomass capable of producing maximum sustainable yields. Relative biomass estimates of LBB were not significantly different from the " true " values in simulated data and were similar to independent estimates from full stock assessments. LBB also presents a new indicator for assessing whether an observed size structure is indicative of a healthy stock. LBB results will obviously be misleading if the length frequency data do not represent the size composition of the exploited size range of the stock or if length frequencies resulting from the interplay of growth and mortality are masked by strong recruitment pulses.
In the Mediterranean Sea, recreational fishing is part of the local culture and has been practice... more In the Mediterranean Sea, recreational fishing is part of the local culture and has been practiced for centuries using various techniques and gears. Yet, recreational fishing effort and catches are not officially recorded in most Mediterranean countries, Greece included. The objective of this work was to estimate the number of vessels fishing for recreational purposes in the Aegean and Ionian Seas (Greece) using two independent sources of data. Firstly, we physically visited 42 ports and marinas across the Greek Aegean Sea coastline and counted the recreational vessels. Secondly, we used satellite image frames (from Google Earth) to count the recreational vessels at the same and in additional 620 ports and marinas of the entire Aegean (420 ports) and Ionian (200 ports) coastlines, including the inhabited islands. The agreement between the in situ visits and the satellite data was very high (correlation coefficient r = 0.96, P < 0.001), indicating that Google Earth is a valuable and low cost tool that provides useful information for fisheries management. According to the satellite data, the total number of recreational fishing vessels was about 24,650 in the 462 ports of the Aegean Sea and 7000 in the 200 ports of the Ionian Sea; this adds up to a total number of around 31,650 recreational fishing vessels in Greek waters, which agrees with the number of recreational fishing licenses issued in 2014 but is lower compared to previous estimates. Most vessels were recorded near large cities, where the majority of inhabitants are concentrated and in islands, where the majority of tourists spend their time.
, the reformed Common Fisheries Policy (CFP) of the European Union is legally binding for all Mem... more , the reformed Common Fisheries Policy (CFP) of the European Union is legally binding for all Member States. It prescribes the end of overfishing and the rebuilding of all stocks above levels that can produce maximum sustainable yields (MSY). This study examines the current status, exploitation pattern, required time for rebuilding, future catch, and future profitability for 397 European stocks. Fishing pressure and biomass were estimated from 2000 to the last year with available data in 10 European ecoregions and 2 wide ranging regions. In the last year with available data, 69% of the 397 stocks were subject to ongoing overfishing and 51% of the stocks were outside of safe biological limits. Only 12% of the stocks fulfilled the prescriptions of the CFP. Fishing pressure has decreased since 2000 in some ecoregions but not in others. Barents Sea and Norwegian Sea have the highest percentage (> 60%) of sustainably exploited stocks that are capable of producing MSY. In contrast, in the Mediterranean Sea, fewer than 20% of the stocks are exploited sustainably. Overfishing is still widespread in European waters and current management, which aims at maximum sustainable exploitation, is unable to rebuild the depleted stocks and results in poor profitability. This study examines four future exploitation scenarios that are compatible with the CFP. It finds that exploitation levels of 50–80% of the maximum will rebuild stocks and lead to higher catches than currently obtained, with substantially higher profits for the fishers.
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Books by Athanassios Tsikliras
Papers by Athanassios Tsikliras