Community structure of deep-sea demersal fish in the North Aegean ...

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... M. J., B. A. Roel, A. Badenhorst & J. G. Field, 1993. Analysis of the demersal community of fish and cephalopods on the Aguilas Bank, South Africa. J. Fish Biol.
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Hydrobiologia 440: 281-296, 2000. M.B. Jones, J.M.N. Azevedo, A.I. Neto, A.C. Costa & A.M. Frias Martins (eds), Island, Ocean and Deep-Sea Biology. O 2000 Kluwer Academic Publishers. Printed in the nether land.^.

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Community structure of deep-sea demersal fish in the North Aegean Sea (northeastern Mediterranean) M. Labropoulou & C. Papaconstantinou National Centre for Marine Research, Agios Kosmas, Hellinikon, 16 604 Athens, Greece E-mail: mlabro@ncmsgr Key words: demersal fish, depth zonation, species diversity, habitat width, Eastern Mediterranean

Abstract The spatial structure and seasonal changes of the demersal fish assemblages on the continental shelf (100-200 m) and upper slope (200-500 m) in the North Aegean Sea (Northern Aegean and Thracian Seas, northeastern Mediterranean, Greece) were analysed. Seasonal experimental trawl surveys, carried out from summer 1990 to autumn 1993, provided a total of 15 1 demersal fish species. Analysis of 259 bottom trawls showed the existence of four groups associated with the continental shelf and the upper slope; each group was dominated by a small number of species. The bathymetric distribution of the species, established using measures of the centre of gravity and habitat width, revealed that most of the species had a wide distributional range within the study area, although a few were restricted to the greatest depths. Density, biomass, species richness and diversity decreased significantly with depth, and were also indicative of distinctive characteristics between these fish assemblages. Mean fish weight exhibited two different trends: a bigger-deeper phenomenon at the continental shelf and a smaller-deeper phenomenon at the upper slope. The variability in assemblage structure was determined mainly by depth and, to a lesser extent, by season and geographical location. For some species, results suggest a pattern of gradual species replacement along the depth gradient coupled with ontogenetic habitat shifts.

Introduction Information of soft-bottom fish assemblages in the eastern Mediterranean, where demersal fish are heavily exploited as principal targets or by-catch components, is particularly scarce. Demersal fishes of the North Aegean continental shelf and slope are subjected to intensive fishery carried out by trawl, gillnet and longline fleets. The gillnets and longlines catch a small number of species, whereas the trawl fleet exploits a multi-species fishery targeting several demersal and benthic species. Results of experimental trawl fishing in the North Aegean indicated that all the commercially important demersal and inshore stocks suffer from over fishing. As a result, commercial catches consist mainly of young immature individuals and a variety of non-commercial species that are discarded (Stergiou et al., 1997). Reduction of catch rates and mean size of individuals is a well documented trend in world fisheries (Pitcher, 1996). Consequently, new approaches to the

study of exploited populations have been suggested, including the study of the fish assemblage structure in relation to environmental variables, and the characterization of seasonal changes to improve management practices. As pointed out by Caddy & Sharp (1988), this type of study is a necessary step toward understanding multispecies stocks. Such work can then be extended to descriptive community dynamics to find which general patterns of species compositions can be expected under given environmental conditions and fishing effort. Changes in species composition with depth on continental shelf and slope have been well established for many areas (e.g. Haedrich et al., 1980; Carney et al., 1983; Abelld et al., 1988; Hecker, 1990; Cartes & SardB, 1993; Koslow, 1993; Smale et al., 1993; Cartes et al., 1994; SardB et al., 1994; Gordon et al., 1995; Fariiia et al., 1997a). Both physical and biological factors have been discussed as causes responsible for faunal zonation with depth. Hydrographic conditions, the steepness of the continental slope and sub-

stratum type are amongst the major physical factors considered. Resource availability, predator-prey relationships and interspecific competition are the most important biological factors reported. However, most studies have examined megafaunal assemblages, while little attention has been paid to the structure of the highly exploited demersal fish assemblages, apart from the degree to which different fish species are zoned with depth. Deep-water fish assemblages tend to be more diverse and less dominated by a single species than shelf assemblages, and thus impacts on any one particular species are very likely to be reflected in the responses of others as well as the community as a whole (Merrett & EIaedrich, 1997). Only recently, studies of fish community structure have focused on the patterns of spatial and temporal variation on composition, abundance and distribution of demersal fish assemblages of the continental shelf and slope at several latitudes (Markle et al., 1988; Bianchi, 1991, 1992a, 1992b; Fujita et al., 1995; Fariiia et al., 1997b; Garcia et al., 1998; Moranta et al., 1998). In the present study, the trawl catch data obtained seasonally in 3 successive years (1990-1993) from the continental shelf and the upper slope of the north Aegean Sea were analysed to explore the structure of the demersal fish community. The main objectives were to define the faunal composition, the spatial structure and the main faunistic assemblages in the area, and to investigate whether there are any general trends in the distribution of the fish fauna in relation to environmental factors (mainly depth), season and geographical location.

Material and methods Study area and sampling procedure The North Aegean Sea is one of the least studied regions of the northern part of the Mediterranean. It is an almost rectangular basin, separated from the South Aegean by the archipelago of the Cyclades Islands. The bottom topography of the North Aegean is characterized by a series of deep trenches and troughs (with depths reaching 1600 m), separated by shallow sills and shelves. The northern part of the sea, the Thracian Sea, lies over an extended shelf and is separated on its west from the Thermaikos Gulf by the peninsula of Chalkidiki. The North Aegean trough, having a SW to NE direction separates the Thracian Sea from the rest of the North Aegean (hereafter: Northern Aegean Sea)

and is characterized by a highly irregular coastline, the presence of many islands and a very narrow continental shelf (Fig. 1). The North Aegean basin is the region where the eastern Mediterranean receives the Black Sea outflow. Black Sea water is the major source of freshhrackish water for the region, as the contribution of all the rivers flowing into the Aegean is smaller than the input of the Black Sea by at least one order of magnitude (Poulos et al., 1997). The North Aegean Sea is also influenced by nutrient inputs from outflowing Black Sea waters as well as by freshwater runoff along its northern rim. Therefore, it is characterized by higher nutrient and plant pigment concentrations, in relation to the rest of eastern Mediterranean, and is one of the most oligotrophic marine regions of the world (Stergiou & Pollard, 1994). Environmental parameters (temperature, salinity) are fairly constant along the slope below 200 m (13.5-14 " C and 38.039.0 %o, respectively) (D'Onghia et al., 1995), while muddy sediments generally predominate on the shelf and slope from 100 to 1000 m depth (Lykousis & Collins, 1987). A total of 259 hauls was taken during sixteen experimental bottom trawl survey cruises on a seasonal basis (summer 1990-spring 1992 in the northern Aegean Sea, autumn 1991-winter 1993 in the Thracian Sea) from standard depth stations between 100-500 m (Fig. 1). Sampling stations were selected on a depthstratified random decision and the otter trawl used (foot-rope length: 65.7 m, headline height: 1.5 m) was equipped with a cod-end bag liner of 16 mm stretched mesh size. Samples were collected during daylight between 0800 and 1700 h. The duration of each trawl (bottom time) was 30-60 min, and the trawling speed fluctuated from 2.5 to 3.0 knots depending on the depth and the nature of the substratum. The catch from each haul was sorted and identified to species; each species was enumerated and weighed individually on board. Part of the catch was frozen or preserved in formalin for later study in the laboratory. Since all hauls were carried out using the commercial trawl vessel 'Ioannis Rossos' and the same fishing gear it was assumed that gear selectivity was constant. Those species regarded as markedly pelagic or semi-pelagic in behaviour were disregarded from the analyses since they had not been sampled quantitatively.

Data analysis Species abundance and biomass were calculated for each haul after standardization of the data to a 1 h

Figure 1. Sampling stations on the continental shelf and the upper slope of the North Aegean Sea. (+) Thracian Sea, (a) northern Aegean Sea.

tow, malung it possible to allow comparisons between sampling stations. To identify zonation patterns, principal components analysis and cluster analysis were applied to the species abundance matrix. Principal component analysis was performed on the 259 sample correlation matrix of 151 species (excluding pelagic and semi-pelagic species). Before the analysis, abundance values were log (x+l) transformed. Cluster analysis (group average) employed the Bray-Curtis similarity index (Field et al., 1982) and was performed on the standardized abundance values of the species using the PRIMER algorithms (Plymouth Marine Laboratory). To normalize the data and avoid skew, a square root transformation was applied to the abundance data prior to cluster analysis (Field et al., 1982). Multidimensional scaling (MDS) ordination analysis was also performed with the same configuration as in cluster analysis with respect to similarity index and transformation. The typifying and discriminating species of the cluster of stations were determined using the SIMPER procedure (Clarke, 1993). This procedure indicates the average contribution of each species to the similarity (typifying species) and dissimilarity (discriminating species) between groups of samples.

The bathymetric distribution of the dominant species, according to their abundance rank in each station group identified by cluster analysis, was calculated in a quantitative way using the 'centre of gravity' (COG) (Daget, 1975; Stefanescu et al., 1992a; Moranta et al., 1998) and 'habitat width' (HW) (Pielou, 1969) analyses. The COG model allows the calculation and location with precision of the centre of species distribution by means of a descriptor (such as depth), while the HW model gives a measure of heterogeneity of the species distribution. The ecological parameters of abundance, biomass, mean fish weight, number of species (S), species diversity, Shannon-Wiener index ( H f = (Hurlbert, 1978), species richness (d

n

pi In p i )

r=l = (S=-ll_

(Marlog(^) galef, 1968), and evenness ( I f = -(Pielou, 1966) log(s) were calculated for each of four 100 m depth intervals, where pi = proportion of total sample belonging to ith species and N = the number of individuals. Furthermore, regression analyses were used to determine how these attributes, as well as the scores of principal components analysis, changed with water

depth. Before using parametric tests, the assumptions of normality and homoscedasticity were tested, and when these assumptions were not met, the data were log ( x + l ) transformed (Sokal & Rohlf, 1981; Zar, 1984). All statistical inferences were based on the 0.05 significance level.

Results Overall catch A total of 151 demersal fish species belonging to 61 families was collected in the study area (see Appendix 1). Of these, 106 species were found at depths between 100 and 200 m, and 94 in the bathymetric range of 200-500 m. Twenty species dominated depths between 100-200 m (78.1% of the overall catches), while 1 1 dominated the depths below 200 m (82.7%). The remaining species made up a small and inconstant proportion of the catches. Depth patterns in species composition Principal components analysis for the pooled data revealed that some gradual changes in species composition occurred along the depth gradient. Many sites were grouped together but, in general, the shallowest (< 150 m depth) and the deepest (>400 m depth) stations were set apart in all years by the 1st and the 2nd axis, respectively (Fig. 2). The first 2 principal components, accounting for 48.9% of the total variance, were significantly correlated with depth in linear and polynomial regression, respectively. The score of the 1st axis was greater in deeper water and remarkably well correlated with depth in linear regression. The 1st axis increased with increasing depth because the minimum value was observed for the shallowest depths (Fig. 3a). The score of the 2nd axis was maximum in the intermediate depths around 300 m, indicated by much better fit of the polynomial regression for the pooled data (Fig. 3b). High positive load on the 1st component was found for the deeperwater species (i.e. Hymenocephalus italicus, Nezumia sclerorhynchus, Coelorhynchus coelorhynchus and Gadiculus argenteus argenteus) and high negative load for the shallower-water species such as Serranus hepatus, Mullus barbatus, Mullus surmuletus and Arnoglossus laterna. High positive load on the 2nd component was observed for the species Gadiculus argenteus argenteus, Argentina sphyraena, Lepidorhornbb~s boscii and Micromesistius poutassou poutassou that

dominated the intermediate depths. There did not appear to be any significant pattern of seasonal variation in composition of the catches for any of the station groups resulting from this analysis. Classification and ordination of the 259 trawl catch data in terms of species abundance revealed the existence of four groups associated with the continental shelf and the upper slope (Fig. 4a, b). Groups 1 and 4 consisted entirely of those samples taken from the continental shelf (100-200 m) in the Northern Aegean and Thracian Sea, respectively, while deeper stations for each area were subsequently classified in Groups 2 and 3. However, a relatively small nugber of species contributed most to the simil@@$-&ach group, -. but their relative abundances varied be;ween adjacent groups (i.e. Groups 1-4, Groups 2-3) (Table 1). The bathymetric distribution of the species established using the measures of the centre of gravity (COG) and habitat width (HW)revealed that for both areas most of the species presented a wide distribution range within the study area, although a few were restricted to the greatest depths (Fig. 5a, b). From a total of 26 demersal species analysed, only six were restricted to the depth intervals studied. There were three different species groups: (a) species limited to the 100-200 m depth interval (i.e. Serranus hepatus, Mullus barbatus, Mullus surmuletus and Arnoglossus latema), (b) species with a wide bathymetric distribution (i.e. Merluccius rnerluccius, Micromesistius poutassou poutassou, Lophius budegassa, Scyliorhinus canicula), and (c) species restricted to depths greater than 200 m (i.e. Hymenocephalus italicus, Nezumia sclerorhynchus, Coelorhynchus coelorhynchus, Galeus melastomus, Phycl~ blennoides and Molva dipterygia rnacrophthalma).

.

. . * > * a .

Depth patterns in abundance and species diversity Significant differences in mean species abundance, biomass and diversity indices existed between the four depth zones (Table 2). The highest values of these parameters were found in samples from the continental shelf (100-200 m) and decreased significantly for those from the upper slope. Significant negative regressions with depth were also found for species abundance, biomass and diversity indices for the pooled data from the 3 years of the study (Figs 6 and 7). However, species abundance appeared to be more or less uniform at depths between 200-400 m, while species biomass decreased sharply with depth. Mean fish weight exhibited two different trends within the

Figure 2. Principal component analysis of 259 samples based on demersal fish species abundance. ( A ) Thracian Sea, Sea.

studied depth-range. A steady increase was observed from 100 to 200 m, while the opposite trend was noted from 200 m down to the maximum depth sampled (Fig. 8).

Discussion Two distinctive demersal fish assemblages clearly associated with the topography of the study area have emerged from the analysis: a shallow assemblage reaching the 200 m depth limit which represents the continental shelf, and a deep assemblage beyond that depth which represents the upper slope. The first assemblage exhibits greater abundance and biomass, and contains species of larger size and cornmercia1 interest (such as Merluccius merluccius, Mullus barbatus, Mullus surmuletus and Trisopterus minutus capelanus). The second assemblage is characterized by the presence of species such as Gadiculus argenteus, Hymenocephalus italicus, Coelorhynchus coelorhynchus and Nezumia sclerorhynchus, which

(m) Northern

Aegean

are small and not commercially important. The main determining feature associated with the structure of the demersal fish assemblages is depth, as it reflects the changes from the continental shelf to the continental slope. However, other bottom and oceanographic characteristics do play a role in structuring the assemblages on the continental shelf between the two areas. The main factors which possibly contribute to such a geographical differentiation are the gradient in eutrophy, freshmrackish runoff, temperature and salinity of Aegean Sea waters along a NNW to SSE axis, and the differences in the extent of the continental shelf within these areas of the Aegean Sea. Nevertheless, the most important quantitative boundary for both areas was located around 200 m which separated the species of the continental shelf from those of the upper slope. At this depth, a remarkable decline of species richness, abundance and biomass was noted. In contrast, certain factors of the benthic environment were remarkably stable with depth below 200 m. Sediment structure consisted of a dominant silt-clay fraction

Figure 3. Relationships between the 1st (a) and the 2 nd (b) axes of the principal componenl analysis and depth

throughout and temperature above the sediment was fairly constant. Perhaps this is the major reason for the high degree of similarity observed in the faunistic composition of the upper slope for both the Northern Aegean and the Thracian Sea. Changes in composition of the demersal fish species along the depth gradient were reflected by changes in both abundance and occurrence, even though the species-examined were found over relatively broad depth ranges in the study area. The faunistic differences observed were quantitative, at least with regard to the distribution of the characteristic species in the sampled stations. Not only did the abufid-

ance of the species examined varied significantly with depth but, when the depth ranges of species' occurrence overlap, they appear to have different depths where they reach their maximum abundance. Hecker (1990) suggested that changes in species composition between different megafaunal assemblages were due to the substitution of the dominant and subdominant species throughout the depth gradient by a continuous faunistic turnover. A somewhat similar distribution pattern, with species showing overlapping depth range but with different depths of maximum density, has been also demonstrated for deep-water crustacean spe-

N.Aegean Sea

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Thracian Sea Figure 4. Classification (a) and ordination (b) of the sampling stations based on the species abundance from the Noah Aegean Sea

cies in the Atlantic (Wenner & Boesch, 1979) and in the western Mediterranean (Ahell6 & Cartes, 1992). Depth zonation and community classification studies should take temporal persistence into account, although until now most studies of the zonation of demersal fish do not consider temporal variation (Markle et al., 1988; Bianchi, 1991, 1992a, 1992b; Moranta et al., 1998). Multivariate analyses did not detect any temporal change in the overall structure of the assemblages between the seasonal cruises. These results suggest that changes in the assemblage composition are weakly associated with seasonal changes at least

for our cruise dates. This means that the communities persisted over the three years of the study and that the species ranking also remained constant. Nonetheless, it should be noted that to track temporal persistence of deep-water populations, the length of the time series available must be considered. Comes et al. (1995) identified population shifts during the period 1978 1991 in many demersal species on the northeast Newfoundland shelf. Stock size was declining steadily for many years before changes could be detected in the standard survey catches.

Northern Aegean Sea

Depth (m) Figure 5u. Rathymetric distribution of the dominant fish species from the Northern Aegean Sea. Black circles represent the centre of ~ a v i t y (COG), thick black lines correspond to the habitat width (HW). Black arrows indicate a displacement in real terms of COG, but included in the depth range considered. Numbers 1-8 on the top axis corresponQto the 8 sectors into which the sampled depth interval was divided.

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Figure 56. Bathymetric distribution of the dominant fish species from the Thracian Sea within the depth range studied. Black circles represent the centre of gravity (COG), thick black lines correspond to the habitat width (HW). Black arrows indicate a displacement in real terms of the COG,but included in the depth range considered. Numbers 1-8 on the top axis correspond to the 8 sectors into which the sampled depth interval was divided.

Figure 6. Relationship between species abundance (N) and biomass (W) with depth, calculated by regression analysis for the demersal fish from the North Aegean Sea.

Richness h

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Table I . Dominant fish species based on abundance rank for each station group identified by cluster analysis. Densities (%N) are averaged over all samples in each group

%N

Northern Aegean Sea

Cum.%

Thracian Sea

%N

Cum.%

100-200 m (Group 4) Trisoprerus rninutus capelanus Merluccius merluccius Argentina sphyraena Serranus hepatus Laphrus budegassa Scyliorhinus canicula Lepidorhombus boscii Gadrculus argenteus

100-200 rn (Group 1) A rgentina sphyraena

Merluccius rnerluccius Lepidotrigla cavillone Scyliorhinus canicula Mullus barbatus Capros aper Serranus hepatus Aspitrigla cuculus Trisopterus rninutus capelanus Trigla lyra

Callionyrnus maculatus Arnoglossus laterna Lepidotrigla cavillone Cepola rubescens Mullus barbatus Capros aper Phycrs blennoides

Lepidorhornbus boscii Citharus linguatula Mullus surrnuletus Lophius budegassa Raja clavata

200-500 rn (Group 2) Hymenocephalus italicus

200-500 m (Group 3) Gadiculus argenteus Hyrnenocephalus italicus Lepidorhombus boscii Micromesistius poutassou Lophius budegassa Phycis blennoides Coelorhynchus coelorhynchus Merluccius merluccius

Coelorhynchus coelorhynchus Nezumia sclerorhynchus Lepidorhombus boscii Phycis blennoides Micrornesistius poutassou Merluccius rnerluccius Lophius budegassa Galeus melastomus Molva dipterygia macrophthalma

Table 2. Ecological parameters by depth zone and summary of statistical tests for the demersal fish community in the No~thAegean Sea

Depth

Biomassa

Abundancea

Mean fish

Number of

Richness

Diversity

Evenness

(g h 1 )

(fish h-')

weight (g)

species (S)

(dl

(HI)

(J')

a Mean and SE were calculated using log ( x

+ 1) -transformed data

all cases P < 0.001.

Overall in the Greek seas, a total of 447 fish species belonging to 129 families has been reported (Papaconstantinou, 1988). Thus, the number of species recorded in the present study represents 38.9% of the total marine ichthyofauna of Greece. However, specks

diversity reveals different trends along the entire range of the depths examined. The continental shelf was characterized by high species richness and diversity, but both parameters decreased remarkably with depth. On the other hand, although evenness was negatively

Figure 8. Relationships between mean fish weight and depth calculated by regression analysis for the demersal fish from less than and greater than 200 m depth in the North Aegean Sea.

correlated with depth, it appeared to be more or less uniform along the depth gradient, indicating a small variability in the numerical co-dominance of species over the depth range examined. The bigger-deeper trend on the continental shelf (100-200 m) resulted primarily from the 'withinspecies' positive size-depth relationships observed for the dominant species (i.e. Mullus barbatus, Mullus surrnuletus, Merluccius rnerluccius, Trisopterus rninutus capelanus). These species inhabit shallow coastal areas and undertake ontogenetic migrations towards deeper waters as they grow larger (Macpherson & Duarte, 1991). The decrease in biomass below 200 m, coupled with the uniformity in abundance values, resulted in a smaller-deeper trend at these depths. Large-sized species were scarcer and were replaced by smaller ones such as Macrouridae which dominated the upper slope. Depth-size trends in deep-sea fish have been a controversial subject in recent years. A general tendency for larger fish to occur in deeper water has long been known with respect to deep-sea fishes (Haedrich & Rowe, 1977); however, it has also been reported for many demersal fishes of the continental shelf (Macpherson & Duarte, 1991). Contrary to these findings, Stefanescu et al. (1992b) observed a smaller-deeper trend for the demersal fish species in the Catalan Sea between 1000 and 2250 m depth, while Moranta et al. (1 988) reported a bigger-deeper phenomenon for fish from the upper and middle slopes of the Balearic Islands and an opposite trend at depths

below 1100 m. It appears that bathymetric trends in fish size are not a generalized phenomenon but these relationships are determined largely by factors such as the species under consideration, the study area and the depth ranges examined. Moreover, Merrett et al. (1991) concluded that an accurate indication of ichthyofaunal structure with increased soundings can only be achieved through a detailed knowledge of the size structure of each species over its entire sounding range synthesized from a multi-trawl investigation via analyses of species fidelity. Despite the enforcement of management regulations for demersal and inshore fisheries in Greek waters (i.e. closed seasons and areas, Limited issue of licenses, minimum legal landing size and mesh size regulations), the fishing effort in the North Aegean, as well as in the rest of the Aegean Sea, is very high (Stergiou & Pollard, 1994). Studies in other areas, based on extended time series during which major increases in fishing effort took place, indicated that this factor causes a decrease in the catches of exploited species and increases in other non-commercial species (Overholtz & Tyler, 1985; Rothschild, 1992). In the present study, the fish assemblages under consideration have suffered a long history of fishery exploitation. Therefore, overfishing has affected the population structure and density of the demersal fish communities, at least at depths up to 200 m, where most of the fishing activity is focused. According to Stergiou & Pollard (1994), who analysed the commercial catch weights of

10 fishing sub-areas of the Aegean Sea for the period 1982-1987, the mean catch of the northern group was dominated by grey mullet, hake and soles, representing 10.376, 8.3% and 5.4% of the mean catch, respectively. However, the results from the present study indicate that most of the dominant species (according to their abundance rank in each station group) are non-commercial species. It is possible that the organization of the demersal fish assemblages analysed are determined to a great extent by an unidirectional trend induced by the fishery, the particular bottom topography and the oceanographic characteristics of the study area. In summary, depth gradient, with its associated environmental and biological changes, is the main factor responsible for faunal changes in demersal fish community of the North Aegean Sea. Differences noted were more consistent with depth-related changes in community structure than with the geographical location of the study sites. Changes in demersal fish community were reflected by changes in both abundance and occurrence along the depth gradient, but the faunistic differences observed were more quantitative than qualitative, at least with regard to the distribution of the characteristic species in the stations sampled. Acknowledgements The authors would like to thank all those involved in demersal trawl surveys in the Northern Aegean and Thracian Seas, carried out by the Fisheries Department of the National Centre for Marine Research, for their valuable help. This work was partially supported by the EU, DG XIV under the Contract No MA-1-90, and the Greek General Secretariat for Research and Technology.

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Appendlx I. Spccles list of demcrsal fish In the North Aegean shelf and upper slope Hexanchidae Scyllorhinidac

Triakidac Oxynot~dae Torped~nidae

Hepfra~zchiasperlo

Myctophidae

Aspitrigla cuculus

Lampanycrus crocodilus

Dentex macrophthalmus

Eufrigla gurnardus

Scyl~orhinusstr1lrzrz.s

Mycfophum puncfufus

Diplodus annularis

Lepidotr~glacavlllone

Mustelus asterias

Nntoscopelus elongatus

Diplodus vulgaris

Lepidotrigla dieuzeidei

Oxynotu.~centrrna

Myctophzdae sp.

Pagellus acame

Trrgla l ~ l c e r n a

Torpedo marmnrata

Neftasfnma melanurum

Pagellus bogaraveo

Trigla b r a

Conger conger

Pagellus eryfhrinus

Echelur myrus

Pagrus pagrus

Ophlsurus serpens

Sparus aurata

Nofocanfhus banapartel

Spondyliosoma canfharus

Squalus hluinvrllrt Squafrno ocularo Squarina squatrnu

Congridae Ophichithidae Notocanthidae Belonidae Macrorarnphosidae Syngnathidae Macrouridae

Belone belone gracilis

Phrynorhombus regius

Coelnrhynchus coelorhynchus

Spicara smaris

Trachyrhynchus frachyrhynchus Merlucczus merluccius Gadiculus argenfeus argenfeus

Labridae Trachinidae Uranoscopidac Gempylidae Trichiuridae Gobiidae

Acanfholabrus palloni

Arnoglossus rucppelli Arnoglossus rhori

Uranoscopus scaber Lcpidopus caudafus

Microclzirus variegatus

Delfenfosfeus quadrimaculatus

Monochirus h~spldus Solea kleinii

Rnja oxyrit~chus

Mlcromesrsfius poufassou poufassou

Gobius niger

Raja polysrlgma

Molva dzpterygia macrophthalma

Gnbius paganellus

Raja radula

Phycis blennnides

Lcsueurigoblusfriesii

Dasyatis pastinoca

Phycls phycrs

Myliobatis a q u ~ l a

Trlsnpterus minutus capelanus

Callionymus macularus

Gadella m a r a l d ~

Callionymus risso

Chauliodus s l o a n ~ Stomias boa

Capros aper Anthias anfhias

Arger~tirzasphyraena

Callanfhias ruber

Glossanodon 1e1nglossu.r

Serranus cabrilla

Microsfoma mlcrosfoma

Serranus hepatus

Synodus SaUrUS

Apogonidae

Chlorophfhalmus agassizi Cerafoscopelus maderen Diaphus mefopoclampus

Cepolidae Mullidae

Epignnus denticulatus

Blennidae By thitidae Ophidiidae

Blennius ocellaris Bellotria apoda Ophidion rochei Ophidion vassali

Carapidae Centrolophidae Scorpaenidae

Solea v ~ ~ l g a r i s

Cynoglossidae

Calllonymus lyra

Synchiropus phaeton

Hoplosterhus mediferraneus

Bugloss~diumlureum Microchirus ocellarus

Gaidropsarus sp.

Zeus faber

Soleidae

Ruveffus prefiosus

Merlangius merlangus eminus

Maurolicus muelleri

Arnoglossus laterna

Trachinus draco

Raja IILIEVUS

Callionymidae

Scophrhalmus rhombus

Bothidae

Symphodus mediferraneus

Rnla monfogui

A rgyropelecus hemigymnus

Cifharus linguafula Lepidorhombus hoscii Lepidorhombus whifiagonis

Nezumia sclerorhynchus

Moridae Trachichthyidae Zeidae Caproidae Serranidae

Dactyloprerus ~ ~ o l i f a n s

Spicara flexuosa

Rajo brachyuro

Chimaera monsfrnsa

Perisfedion cataphractum

Spicara maena

Rnjo nsrerrns

Merlucciidae Gadldae

Centracanthidae Centracanfhus cirrus

Trigloporus lastovizn

Peristeiidae Dactylopteridae Citharidae Scophthalmidae

Macroramphosus scolopru

Hymenncephalus ifalicus

Raja mzlorefus

Scorpaena scrofa

Boops boops

Syng~lafhussp.

Raja alba

Rajo clavora

Synodontidae Chlorophthalrnldae Myctophidae

Triglidae

Scyllorhirzus conicula

Squalus acanthia.~

Chauliodontidae Stomiidae Argentinidae

Scorpaena porcus

Denrex denrex

Etmopferus splnax

Sternoptychidae

Scorpae~dae

Hygophum benoifi

Sornniosus rostratus

Dasyatidae Myliobatidae

Mullus surmulefus

Galcus mclasfomus

Dalatias licha

Rajldae

Mullidae Sparidae

Diaphus sp.

Torpedo torpedo

Squatinidae

Diaphus rajinesqei

Hexanchus griseus

Carapus acus Cenfrolophus niger Helicolenus dactylopferus

Epigonus telescopus

Scorpaena elongala

Cepola rubescens

Scorpaena loppei

Mullus barbatu.~

Scorpaena nofafa

Symphurus ligulatus Symphurus nigrescens Symphurus sp.

Gobiesocidae Lophidae

Lepadogaster lepadogaster Lophius budegassa Lophius piscatorius