scholarly journals Trends in trawl and purse seine catch rates in the north-eastern Mediterranean

2008 ◽  
Vol 9 (1) ◽  
pp. 49 ◽  
Author(s):  
A. MACHIAS ◽  
K.I. STERGIOU ◽  
S. SOMARAKIS ◽  
V.S. KARPOUZI ◽  
A. KAPANTAGAKIS

Data on fishing effort expressed in vessel days at sea and corresponding landing/day for a large number of species have been collected by the Institute of Marine Biological Resources (IMBR) since the second half of 1995. Data were collected over a grid of 21 stations throughout the Greek seas. In the present study we analyzed the monthly days at sea as well as catch per day for trawlers and purse seiners from 1996 to 2000, by general linear models and trend analysis. The following vessel size groups per gear were considered: (a) trawlers smaller and larger than 20m; (b) purse-seiners smaller and larger than 15m. Collected data were also aggregated for five fishing sub-areas: the North Aegean, the Central Aegean, the South Aegean, Cretan waters and the Ionian Sea. Trend analysis of landing/day time series indicated that demersal and pelagic resources are declining in the main fishing grounds. Declining landing/day trends are regarded as indicators of overfishing, especially in the light of the fact that high catch rates are maintained by fishing in ‘hot spots’. The results of the present analysis provide, for the first time, important information on the sustainability of the fisheries in the north-eastern Mediterranean, an area characterized by a complete lack of accurate long-term data on effort and catch per effort


2020 ◽  
Vol 71 (4) ◽  
pp. 257-272
Author(s):  
Onat Başbay ◽  
Mudar Salimeh ◽  
Eddie John

We review the continuing and extensive spread of Papilio demoleus in south-eastern Turkey and in regions of Turkey and Syria adjacent to the north-eastern Mediterranean. Since the authors documented the arrival of this attractive but potentially destructive papilionid species at coastal areas of Syria in 2019, regular monitoring has confirmed successful overwintering there, as well as in Turkey. As previously indicated, P. demoleus is widely recognized as an invasive pest species in Citrus-growing areas of the world and hence its arrival is of potential economic importance to a region in which citrus is widely grown.



2010 ◽  
Vol 15 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Yannis N. Krestenitis ◽  
Yannis S. Androulidakis ◽  
Yannis N. Kontos ◽  
George Georgakopoulos


2002 ◽  
Vol 3 (1) ◽  
pp. 5 ◽  
Author(s):  
V. ZERVAKIS ◽  
D. GEORGOPOULOS

The combination of two research projects offered us the opportunity to perform a comprehensive study of the seasonal evolution of the hydrological structure and the circulation of the North Aegean Sea, at the northern extremes of the eastern Mediterranean. The combination of brackish water inflow from the Dardanelles and the sea-bottom relief dictate the significant differences between the North and South Aegean water columns. The relatively warm and highly saline South Aegean waters enter the North Aegean through the dominant cyclonic circulation of the basin. In the North Aegean, three layers of distinct water masses of very different properties are observed: The 20-50 m thick surface layer is occupied mainly by Black Sea Water, modified on its way through the Bosphorus, the Sea of Marmara and the Dardanelles. Below the surface layer there is warm and highly saline water originating in the South Aegean and the Levantine, extending down to 350-400 m depth. Below this layer, the deeper-than-400 m basins of the North Aegean contain locally formed, very dense water with different θ /S characteristics at each subbasin. The circulation is characterised by a series of permanent, semi-permanent and transient mesoscale features, overlaid on the general slow cyclonic circulation of the Aegean. The mesoscale activity, while not necessarily important in enhancing isopycnal mixing in the region, in combination with the very high stratification of the upper layers, however, increases the residence time of the water of the upper layers in the general area of the North Aegean. As a result, water having out-flowed from the Black Sea in the winter, forms a separate distinct layer in the region in spring (lying between “younger” BSW and the Levantine origin water), and is still traceable in the water column in late summer.



2021 ◽  
Vol 22 (3) ◽  
pp. 653
Author(s):  
ATHANASIOS GKANASOS ◽  
EUDOXIA SCHISMENOU ◽  
KOSTAS TSIARAS ◽  
STYLIANOS SOMARAKIS ◽  
MARIANNA GIANNOULAKI ◽  
...  

We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and sardine, online coupled to an existing hydrodynamic/biogeochemical low-trophic level (LTL) model for the North Aegean Sea. It was built upon an existing 1D model for the same species and area, with the addition of a horizontal movement scheme. In the model, both species evolve from the embryonic stage (egg+yolk sac larva) to the larval, juvenile, and adult stages. Somatic growth is simulated with the use of a “Wisconsin” type bioenergetics model and fish populations with an adaptation of the ‘super individuals’ (SI) approach. For the reference simulation and model calibration, in terms of fish growth and population biomass, the 2000-2010 period was selected. Interannual biomass variability of anchovy was successfully represented by the model, while the simulated biomass of sardine exhibited low variability and did not satisfactorily reproduce the observed interannual variability from acoustic surveys. The spatial distribution of both species’ biomass was in relatively good agreement with field data. Additional single-species simulations revealed that species compete for food resources. Temperature sensitivity experiments showed that both species reacted negatively to a temperature increase. Anchovy, in particular, was more affected since its spawning and larval growth periods largely overlap with the period of maximum yearly temperature and low prey concentration. Finally, simulation experiments using IPCC climatic scenarios showed that the predicted temperature increase and zooplankton concentration decrease in the future will negatively affect anchovy, resulting in sardine prevalence.



Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1678
Author(s):  
Carmelo Maria Musarella ◽  
Salvatore Brullo ◽  
Gianpietro Giusso del Galdo

The results of a phytosociological investigation regarding the orophilous cushion-like vegetation occurring in the top of the high mountains of central-southern Greece and in some Ionian (Lefkas, Cephalonia) and Aegean Islands (Euboea, Samos, Lesvos, Chios and Thassos) are provided. Based on 680 phytosociological relevès (460 unpublished and 220 from literature), a new syntaxonomical arrangement is proposed with the description of a new class, including two new orders, eight new alliances, and several associations (many of them new). Compared to the previous hierarchical framework usually followed in the literature, this study provides a more realistic and clear phytosociological characterization of this peculiar and archaic vegetation type, which is exclusive to the high mountains of the north-eastern Mediterranean. The new arrangement is mainly based on the phytogeographical role of the orophytes featuring this very specialized vegetation, which is essentially represented by endemics or rare species belonging to the ancient Mediterranean Tertiary flora. In addition, taxonomic research on the orophilous flora occurring in these plant communities allowed to identify six species new to science (i.e., Astragalus corinthiacus, Allium cremnophilum, A. cylleneum, A. orosamium, A. karvounis, and A. lefkadensis) and a new subspecies (i.e., Allium hirtovaginatum subsp. samium), and two new combinations (i.e., Astragalus rumelicus subsp. euboicus and subsp. taygeticus) are proposed.



PLoS ONE ◽  
2019 ◽  
Vol 14 (8) ◽  
pp. e0219671 ◽  
Author(s):  
Athanasios Gkanasos ◽  
Stylianos Somarakis ◽  
Kostas Tsiaras ◽  
Dimitrios Kleftogiannis ◽  
Marianna Giannoulaki ◽  
...  


2004 ◽  
Vol 89 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Evdokia Kourelea ◽  
Dimitrios Vafidis ◽  
Chariton-Charles Chintiroglou ◽  
Georgios Trontsios ◽  
Louis Chicharo


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