Fishing near sea-cage farms along the coast of the Turkish Aegean Sea

This study reports on the yield of commercially important species captured intentionally around and under fish-cage farms using specific types of gear from both sea-cage farmers and artisanal fishermen, and to identify the species composition of these catches. The 2004–2008 research was carried out in 21 fish farms, randomly chosen along the coast of Izmir Province on the Aegean Sea. A total of 91 persons were interviewed, including directors, fishers from the fish farms and artisanal fishermen. The technical characteristics of a special trap used by some fish farmers were diagramed. Total wild fish catch quantities as well the species raised in the sea-cages were recorded. A total of 34 finfish and four invertebrate species were identified from the sea-cage farm fishery. Eight fish species according to the descending quantities raised were bogue ( Boops boops ), grey mullet ( Mugil spp.), blackspot seabream ( Pagellus bogaraveo ), salema ( Sarpa salpa ), common two-banded seabream ( Diplodus vulgaris ), annular seabream ( Diplodus annularis ), striped seabream ( Lithognathus mormyrus ) and gilthead seabream ( Sparus aurata ). Mean quantities of wild fish caught from 2004 to 2008 in a sampled farm were 13 998 ± 210, 34 434 ± 482, 30 116 ± 529, 27 893 ± 429, and 32 366 ± 808 kg, respectively. There were significant differences between fish amounts and years (P   < 0.05).     

The status of fishery cooperatives along the Aegean Sea coast (Turkey)

The objective of this study was to document the present status of fishery cooperatives on the Turkish Aegean Sea coast while at the same time exploring membership expectations and overall involvement of the fishery community in the cooperative sector. To achieve this goal, a survey assessed 92% (n = 56) of the Turkish fishery cooperatives in the Aegean region. Using cluster analysis, the cooperatives were divided into three groups based on six of their provided services. Group 1 provided a good level of services; the number of members per cooperative was relatively low in this group, but the cooperatives fulfilled most of their objectives. Group 2 consisted of the youngest cooperatives and had the highest number of members per cooperative, with one‐third of the members relying on fishing as their sole income; cooperatives in this group were the least able to provide services to their members. Group 3 consisted of the oldest cooperatives with the highest number of fishery‐dependent members; cooperatives in this group were the most able to provide services and to meet members objectives. After grouping the cooperatives, a Tobit model was used to determine factors affecting the membership ratio. The Kolmogorov–Smirnov normality test was run to verify that the variables conformed to normal distributions, and the Kruskal–Wallis test compared the different groups. Results showed that the ages of the cooperatives and the existing government policies regarding fishery cooperatives and conflicts among members had significantly negative effects on membership ratios whereas periodic changes in the management board had significantly positive effects. These results will be useful for decision makers in designing suitable policies for the better management of fishery cooperatives.     

Short-term climate changes in the southern Aegean Sea over the last 48,000 years

High-resolution palaeoenvironmental changes, corresponding to a mean time interval of 450 years covering the last 48,000 years, were examined in a core from the Cretan Basin in the southern Aegean Sea. The intensity and duration of the climatic and oceanographic events were determined by examining the compositional changes in the planktonic foraminifera and pollen assemblages, along with the δ¹⁸O signal of Globigerinoides ruber. A reconstruction of sea-surface temperatures was attempted using the Modern Analogue Technique (MAT). In total, 10 stadials and 6 interstadials occurred over the last 48,000 years. These fluctuations in climatic conditions coincide with fluctuations documented in the western and central Mediterranean and seem to be associated with Dansgaard–Oeschger events. Some of these climatic fluctuations are correlated with changes in the vegetation in the surrounding land.

Between 48 and 10 cal kyr BP the most pronounced stadials occurred at 41 cal kyr BP (C69-ST10) and at 13 cal kyr BP (C69-ST4). These events are characterized by: (i) high positive δ¹⁸O values of Globigerinoides ruber, (ii) drops in SST and (iii) increases in aridity. These events may be correlated with the Heinrich H4 event and the Younger Dryas event, respectively. Two other stadials at 23 cal kyr BP (C69-ST6) and at 16 cal kyr BP (C69-ST5) which are characterized by increases in the abundance of the cold plaktonic foraminifera species and increases in aridity may be correlated with the H2 and H1 events, respectively. The dominant planktonic foraminiferal species during the stadials witch are correlated with the Heinrich events were Turborotalita quinqueloba and Globorotalia scitula. The most pronounced interstadials occurred between 39.5 and 38.5 cal kyr BP (C69-IST6) and between 25 and 24 cal kyr BP (C69-IST3) and are characterized by depletion in δ¹⁸O values, increases in SST and increases in humidity. The former event coincides with the formation of the sapropelitic layer S2.

In the Holocene the most pronounced stadial occurred between 8 and 6.5 cal kyr BP (C69-ST2), during the interruption of S1 and is characterized by a reduction in SST and an increase in aridity. The most pronounced interstadials of Holocene occurred during the formation of S1a and S1b between 9 and 8 cal kyr BP (C69-IST1) and between 6.5 and 5.5 cal kyr BP (C69-IST2), respectively. These events are characterized by depletion in δ¹⁸O values, increased SST and an increase in humidity as is indicated by the expansion of temperate evergreen and Mediterranean taxa in the pollen record.     

Fish by-catch species from coastal small-scale shrimp trammel net fishery in the Aegean Sea (Izmir Bay, Turkey)

Fish by‐catch from coastal small‐scale shrimp trammel net fishery was estimated from fishery‐dependent surveys in Izmir Bay (Aegean Sea), Turkey, during the 2004 and 2005 fishing seasons. Sampling data were obtained from 170 observations onboard 18 commercial fishing vessels. Fifty‐two species belonging to 31 families of fish, including cephalopods, constituted the by‐catch. Diplodus annularis was the most abundant by‐catch species followed by Loligo vulgaris > Sepia officinalis > Mullus barbatus > Boops boops > and Solea vulgaris. The estimated total ratio of fish by‐catch to shrimp was 1 : 1.09 kg.     

Spatial management of the Mediterranean bottom-trawl fisheries: the case of the southern Aegean Sea

A time series of survey abundance indices for commercially important demersal fish and cephalopod species, inhabiting the narrow continental shelf of the southern Aegean Sea, is analyzed in relation to the topography of the area in order to evaluate the impact of different spatial fishery bans on the bottom-trawl fishery. With reference to the current situation, results suggested that implementation of the 1967/2006 EC Regulation, which bans bottom-trawl activities within 1.5 NM off the coast, will significantly increase (20–80%, depending on the species) the proportion of the populations that are inaccessible to the bottom-trawl fishery. It might also result in shifting of fishing activities toward deeper waters, adding fishing pressure onto slope resources inhabiting the slope. As depth determines, to a large extent, the distribution pattern of the species, it constitutes a variable of crucial importance for the spatial management of marine fisheries and should be taken into account when adopting relevant management regimes.     

A comparative study of success and failure of fishery cooperatives in the Aegean, Turkey

This study assessed the performance of fishery cooperatives in six selected fishing areas along the central and southern Aegean coasts of Turkey during the 2002–2003 fishing season, in particular with regard to their stated objectives (e.g. member-fisher satisfaction recognition by fishery management authorities). A total of 127 member-fishers (72% of all active fishers in the study area) as well as fishery cooperative directors were interviewed. The results indicated the various strengths of these cooperatives as well as their limitations. Performance below full potential was due to internal factors such as lack of solidarity and qualified business management skills, as well as external factors relating to weak legislative support by the government, the tax system and the lack of training. However, through their contribution to local society and their function in assisting management bodies, cooperatives play a significant role in Turkish small-scale fisheries. They are therefore in need of further capacity building through specific encouragement from the government, academics, and fishers in order to improve their performance.     

Genetic studies in four populations of the northern Aegean Sea, Greece

A total of 945 non-related individuals from four isolated population groups from the Northern Aegean Sea (Greece)--Alonissos, Oxilithos, Skopelos, and Glossa, has been typed for 16 polymorphic systems of the blood, namely A1A2B0, MNS., Rhesus (C, c, Cw, D, E, e), Kell, Duffy (a,b), Kidd (a); Hp, Tf subtypes, Gc, Gm (1, 2, 3, 5, 13), Km (1); aP, AK, PGM1, EsD, and 6-PGD. The distribution of phenotype and gene/haplotype frequencies shows a considerable interpopulational variability, which is discussed considering the history of these populations as well as the impact of locally acting microevolutionary factors such as drift and founder effects. The average coefficient of gene diversity GST comes to 0.0147, whereas Wahlund's variance is on average 0.0154, and Wright's Fst = 0.0147. Genetic distance analysis reveals a pattern of similarities, which is in conformity with the history of the populations under study.     

Coralligène formations in the eastern Mediterranean Sea: Morphology, distribution, mapping and relation to fisheries in the southern Aegean Sea (Greece) based on high-resolution acoustics

Coralline algae are one of the most important constructors of biogenic habitats. In the Mediterranean Sea, the dominant coralline algae species form crusts comprising formations known as coralligène, considered as very important fishing grounds by fishermen. Due to the destructive effect of fishing gear activities over coralligène, these formations were recently protected from the use of active benthic gears by the EU 1967/2006 Mediterranean fisheries management Regulation. However, the lack of maps and information on their distribution makes the effective application of these measures impossible. The present publication contributes to the mapping of coralligène in the southern Aegean Sea (eastern Mediterranean), and to the study of coralline algae formation morphology, distribution, development conditions and relation to fisheries using a combination of single-beam echo sounder, sidescan sonar, sub-bottom profiler recordings and biological and sedimentological ground-truthing techniques. The coralligène formations were recognized as two distinct acoustic signatures of localized backscatter facies distinguishable from other hard substrate reflectors at depths ranging from 55.9 to 114.0 m, but mainly between 70 and 90 m. Two types of formations were identified: minute reefs 0.5-2.5 m in height and superficial layer formations no more than 0.2 m thick over the substrate. The seismic profiles revealed a cavernous internal structure of the minute reefs and recorded their development on both hard and soft substrates. The distribution of formations was contagious, creating aggregations. The finding of superficial layer formations and coralline shreds around minute coralligène reefs indicated that the former could be an intermediate development type between isolated small coralline pebbles, rhodoliths, and minute reefs. Regarding the development conditions, sidescan sonar imagery indicated that the optimal conditions for the establishment and development of coralligène formations are medium intensity currents. Concerning human activity over coralligène, trawl traces were recorded near but not over minute reefs and both near and crossing superficial layer type aggregations, while a submarine cable was also recorded among minute reefs. The mapping of coralligène aggregation areas is essential for the application of the EU Regulation and the protection of this important marine habitat.     

Feeding Ecology of Black-bellied Anglerfish Lophius budegassa in the Central Aegean Sea,Turkey

Journal of Ichthyology - Anglerfishes Lophius spp. are gaining high economic value day by day and becoming demand species worldwide. The black-bellied anglerfish, Lophius budegassa (Spinola, 1807)...     

Mesozooplankton distribution in relation to hydrology of the Northeastern Aegean Sea, Eastern Mediterranean

The Northeastern Aegean Sea (NEA) is the area where Black Seawaters (BSW) outflow in the Mediterranean enhancing local productivityand inducing high hydrographic complexity. We describe the structureand distribution (both vertical and horizontal) of mesozooplanktonassemblages in the NEA during the thermal stratification periodin July and September 2003, in an effort to identify BSW effects.The overall standing stocks of mesozooplankton in the NEA weremuch higher than those typically reported for other pelagicwaters of the eastern Mediterranean. Higher abundance and biomassvalues and a distinctive copepod and cladoceran species assemblagewere recorded in the surface layer (directly influenced by theBSW). Variability in the supply and subsequent advection ofBSW in the NEA seemed to be the major factor affecting the structureand distribution of mesozooplankton assemblages. In July, lowersurface salinity reflected the increased supply of BSW (richin organic carbon) and, consequently, the abundance of filterfeeding taxa (cladocerans, appendicularians and doliolids) washigher than in September. During both surveys, the copepod/cladoceranassemblages of the surface (0–50 m) layer were sensitivetracers of horizontal hydrological and biological variability(e.g. location of fronts) associated with the advection of theBSW. This paper was presented at Plankton Symposium III, held atFiguera da Foz, Portugal between 17 and 20 March 2005, underthe auspices of the University of Coimbra and the Universityof Aveiro, and coordinated by Mário Jorge Pereira andUlisses M. Azeiteiro.     

Determination of batch fecundity in Uranoscopus scaber Linnaeus, 1758 from the Aegean Sea, Turkey

This work focuses on reproductive biology aspects of Uranoscopus scaber from the coast of the Aegean Sea. In total, 175 U. scaber specimens were collected in Izmir Bay using trawl nets from January to December 2005. The reproduction period according to gonadosomatic index (GSI) values extents from March to September, with a peak in May (6.32 ± 1.2). Oocyte diameters taken from 59 mature gonads ranged from 62 to 1860 μm. Maximum batch fecundity (BF) was 58091 (mean: 11556 ± 1445) in large oocytes in May, and 8408 (mean: 2821 ± 945) in hydrated oocytes in September. The BF increased with total length and body weight, excluding the ovaries. Total length (TL)–BF relationships and fish weight–BF relationships were BF = 0.0034TL^4.6248 (r = 0.47) and BF = 59.166W?3101 (r = 0.49), respectively, according to the oocyte size frequency method. There was a linear relationship between BF and fish size.     

The occurrence and behaviour of phosphate fractions in Izmir Bay, Aegean Sea

The area around Izmir Bay (Turkey) is heavily urbanized and receives, therefore, high concentrations of phosphate originating from industrial and municipal inputs. During the surveys between April 1993 and July 1994, the total phosphate concentrations were highest in the Inner Bay (6.45 M and 5.59 M in the surface and bottom water, respectively) where very dense anthropogenic pollution occurs. The total phosphate value gradually decreased towards the Outer Bay where 0.70 M and 1.18 M were found in the surface and bottom water, respectively. The distribution of dissolved inorganic, dissolved organic and particulate phosphate along the bay reflected some peculiar spatial and temporal patterns. A high percentage of dissolved organic phosphate was observed in the Outer Bay while the particulate phosphate peaked in the Middle Bay where an upwelling mechanism was observed. In the bay, the biological production was strongly correlated with the variations in the dissolved inorganic, organic and particulate phosphate. The high phosphate concentration in particles caused the particulate phosphate formed in the Inner Bay to be transported to the outer parts of the bay because of the short water residence time. On the other hand, Principal Component Analysis showed that about 35% of the variation in all variables measured were related to the total phosphate, total dissolved phosphate, dissolved inorganic phosphate and particulate phosphate together with ammonium and reactive-Fe while about 14% of the variation was related to the dissolved organic phosphate and the number of phytoplankton cells, chl-a, pH and O₂.     

Nutrient-dependent variation in growth and longevity of the red bandfish, Cepola macrophthalma, in the Aegean Sea

Statistically significant regressions are presented between the maximum observed age, maximum gross weight, mean total length, mean gross weight, and mean weighted back-calculated total length at ages 3 and 4 years for red bandfish, Cepola macrophthalma , and the total nitrogen in three Aegean gulfs. In contrast, the regressions of all the above mentioned biological variables on phosphates in the three gulfs were not significant, a fact consistent with the view that nitrogen, as opposed to phosphorus, is the limiting factor in eastern Mediterranean marine ecosystems. After discussing possible genetic discontinuities between the three populations, being inferred from the paleoceanography of the study area, it is suggested that the three populations form a single gene pool expressing phenotypic plasticity shaped by the contrasting environmental conditions experienced.     

Zooplankton distribution and diversity in a frontal area of the Aegean Sea

This study was carried out in the northern Aegean Sea during late summer and spring. The aim was to examine the spatial and temporal distribution of the zooplankton community across a dynamic frontal area and to investigate how the oceanographic heterogeneity structures the composition of the zooplankton assemblages. The low-salinity and cold Black Sea water coming from the Dardanelles Strait is modified by mixing with the underlying warm and saline Aegean water. These hydrological features result in a pronounced thermohaline front in the northern Aegean Sea throughout the year. In both seasons, zooplankton was collected using both 45 and 200 µm mesh plankton nets. A high abundance of zooplankton was observed in the surface layer at the stations closest to the Dardanelles Strait on the stratified side of the front. The zooplankton distribution and community structure in the northern Aegean Sea were strongly influenced by the hydrological features. The frontal structure acts as a boundary for the zooplankton community. The surface layer at the stratified stations had the lowest copepod diversity, from where it increased with depth and horizontally as the stratification weakened outside of the front. The total abundance of zooplankton collected with the 200 µm net was between two and 20 times lower than samples taken with the 45 µm net. The most pronounced differences were observed for the adults and copepodids of the small genera Oithona, Oncaea and Microsetella. Thus, to manage and understand the transfer of primary production up the food chain in the Aegean Sea, the smaller fraction of copepods should be taken into account in future investigations.     

Dinophysis blooms in Greek coastal waters (Thermaikos Gulf, NW Aegean Sea)

The first documented Dinophysis bloom from Greek coastal watersassociated with a diarrhetic shellfish toxins outbreak was recordedin January 2000 during the HAB monitoring program in ThermaikosGulf. A species with morphological features similar to D. acuminataClaparède and Lachmann dominated this bloom. MaximumD. cf. acuminata abundance (85.4 x 10³ cells L^–1) appearedin February 2000. In 2001, high numbers of D. cf. acuminata(5 x 10³ cells L^–1) were recorded in April under conditionsof weak thermal stratification, while in 2002 maximum numbers(37 x 10³ cells L^–1) of the same species were found inFebruary under low temperature levels (11.5–12.5°C).All Dinophysis blooms persisted for no more than 4 months. Inaddition to cells resembling typical D. cf. acuminata, cellsof similar shape but smaller in size were observed at differentstages of the blooms. Other observations include couplets oflarge and small-sized cells, and also a larger robust form witha dense granular cytoplasm. The D. cf. acuminata populationalways presented a stratified vertical distribution with verticalpeaks positioned in or just above the pycnocline. Among thephysico-chemical parameters, water temperature appears to bethe most important factor influencing the distribution of Dinophysisabundance.     

A synopsis of the late Miocene Mammal Fauna of Samos Island,Aegean Sea,Greece

As one of the oldest known Eurasian fossil vertebrate localities, Samos late Miocene fauna attracted the interest of specialists by its richness and overall importance. Nevertheless, crucial taxonomical questions and chronological problems obscured its value. The detailed study of the local stratigraphy, the collection of new fossil material and its study, the revision of the old collections and the updated magneto-chronology of the fossiliferous deposits permited to re-discuss most of the problems in a special volume edited in 2009 by Koufos and Nagel and to provide a clearer and more precise idea about the Samos fauna and its age. A synopsis of this work is given here. The systematic study of the new collection (～1200 identified specimens) allows the determination of 42 species from three fossil horizons, ranging from the upper part of early Turolian (MN11) to the end of middle Turolian (MN12). Taxonomic novelties are the presence of the carnivore genus Protictitherium found for the first time in Samos, the establishment of the new name Skoufotragus for Pachytragus Schlosser with the new species Skoufotragus zemalisorum, and the amended morphology of Pseudomeriones and Urmiatherium. Additionally six Hipparion and four Gazella species were recognized and a better morphometric distinction between Samotherium boissieri and Samotherium major was performed. This study also improved the correlation of the old fossiliferous sites with the new ones and with the local stratigraphy of the Mytilinii Basin, while precise ages have been obtained for the mammal localities. The new data together with the old collections indicate the presence in Samos of four chronologically successive mammal assemblages reflecting a “four stages-of-evolution” scheme. The Turolian palaeoenvironment of Samos is determined as an open bushland with thick grassy-floor of C3 graminoids with possible increase of the open and dry character from the beginning to the end of Middle Turolian. The Samos mammal faunas are palaeobiogeographically closer to the Asian ones than to those from the Greek mainland.     

Plankton gross production and respiration in the shallow water hydrothermal systems of Milos, Aegean Sea

Plankton gross production, net community production and darkcommunity respiration were measured at coastal sites aroundthe island of Milos, Aegean Sea, during June and September 1996and June 1997. Sampling sites were chosen to include those withand without visible signs of hydrothermal activity. Planktongross production ranged from undetectable (<0.3 mmol O₂ m-³day-¹) to 3 mmol O₂ m-³ day-¹; respiration rates ranged from1 to 6 mmol O₂ m-³ day-¹. No significant difference was foundbetween gross production or respiration rates measured at hydrothermallyactive areas and gross production or respiration rates measuredat non-venting areas. The dissolved inorganic carbon concentrationvaried by ~200 mmol C m-³ between venting and non-venting sites.Temperature had a pronounced stimulatory effect on the rateof plankton dark community respiration. The T_opt for planktondark community respiration always lay above the highest incubationtemperature of 30°C (i.e. >6°C above in situ temperature).Temperature had less of a stimulatory effect on the rate ofgross production.     

Crassophyllum thessalonicae sp.n. (Octocorallia, Pennatulacea), from the Aegean Sea

A new pennatulacean species, Crassophyllum thessalonicae sp.n. is described from the Mediterranean (North Aegean Sea). This is the first record of a Crassophyllum Tixier-Duri vault, 1961 species from the Mediterranean Sea. The differences between the new species and C. cristatum Tixier-Durivault, 1961, the other known species of the genus, are discussed, and the genus Crassophyllum is critically compared with the other two related genera Pteroeides Herklots, 1858 and Sarcoptilus Gray, 1848.     

Age and growth of the hollowsnout grenadier, Caelorinchus caelorhincus (Risso, 1810), in the Aegean Sea

Age and growth of the hollowsnout grenadier was studied based on samples collected seasonally in the Agean Sea between March 2003 and January 2004. Total length ranged from 9.0 to 21.6 cm. Length–weight relationship was described as a = 0.0032, and b = 3.008. Age determinations based on otolith readings were between 1 and 10 years. The von Bertalanffy growth curve fitted to observed lengths‐at‐age provided parameters of L_∞ = 24.9 cm, k = 0.115 and t_o = ?3.494.