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...
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.
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.
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 ...
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.
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...
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.
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 &lt;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.
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 ...
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.
ABSTRACT: The problem of data-poor situations – where information is insufficient to estimate app... more ABSTRACT: The problem of data-poor situations – where information is insufficient to estimate appropriate reference points and relative stock status – spans a wide range of fi sheries all over the world, including some of the fisheries upon which Beverton and Holt published their work 50 years ago. Here, we look at a range of case studies to illustrate some of the approaches that have been, or have the potential to be, applied to meet the requirements of fisheries management where information is either lacking or highly uncertain. These approaches are diverse, ranging from more classic single-species approaches based upon catch, effort and biological information (tropical and deep-water examples), through the novel use of this information (calculation of catch trophic level in the Cyclades Islands of Greece) and information from markets (small-scale Spanish Mediterranean fisheries, UK inshore fi sheries), to the incorporation of information from similar species or fi sheries (blue shark in the Atlantic). Assessment should be driven by the aims of management, be they resource conservation, sustainable utilization, employment, economic viability, or a combination of these and other aims. Although many of the data poor assessment methods applied concentrate on the assessment of biological resource status, methods to understand the economic drivers of fishers are also detailed. However, such approaches will only be successful where the will of management is strong enough to apply the precautionary approach in the face of uncertainty. In such cases, all available data should be considered and used to inform simple management guidelines and controls that are robust to the uncertainties within data-poor fi sheries.
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Here, we look at a range of case studies to illustrate some of the approaches that have been, or have the potential to be, applied to meet the requirements of fisheries management where information is either lacking or highly uncertain. These approaches are diverse, ranging from more classic single-species approaches based upon catch, effort and biological information (tropical and deep-water examples), through the novel use of this information (calculation of catch trophic level in the Cyclades Islands of Greece) and information from markets (small-scale Spanish Mediterranean fisheries, UK inshore fi sheries), to the incorporation of information from similar species or fi sheries (blue shark in the Atlantic). Assessment should be driven by the aims of management, be they resource conservation, sustainable utilization, employment, economic
viability, or a combination of these and other aims. Although many of the data poor assessment methods applied concentrate on the assessment of biological resource status, methods to understand the economic drivers of fishers are also detailed. However, such approaches will only be successful where the will of management is strong enough to apply the precautionary approach in the face of uncertainty. In such cases, all available data should be considered and used to inform simple management guidelines and controls that are robust to the uncertainties within data-poor fi sheries.