LONG-TERM CHANGES IN THE SPECIES COMPOSITION OF THE LANDINGS BY SUBAREA AND GEAR IN GREEK FISHERIES,

LONG-TERM CHANGES IN THE SPECIES COMPOSITION OF THE LANDINGS BY SUBAREA AND GEAR IN GREEK FISHERIES, 1928-2007 Moutopoulos D.K. 1, Stergiou K.I. 2 1 Technological Educational Institute of Mesolonghi, Department of Aquaculture and Fisheries, Nea Ktiria, 30200 Mesolonghi, dmoutopo@teimes.gr 2 Aristotle University of Thessaloniki, School of Biology, Department of Zoology, Laboratory of Ichthyology, BOX 134, 54124 Thessaloniki, kstergio@bio.auth.gr Abstract In the present study, the historical change in the species composition of Greek landings per fishing subarea and gear (i.e. trawlers, purse-seiners, beach-seiners and small-scale gears) during 1928-2007 was studied. To identify critical periods of time when significant changes of species composition occurred, a multivariate analysis was applied on the mean landing percentages of 69 species per year. The classification indicated two major groups of years; one for 1928-1969 and another one for 1970-2007. Spicara smaris, Sardinella aurita, Sardina pilchardus, Mullus surmuletus and Sarda sarda each decreased in more than six subareas from 1928-1969 to 1970-2007, depending on the species and gear. In contrast, Boops boops, Engraulis encrasicolus, Merluccius merluccius, Mugilidae, Octopus vulgaris, Thunnus spp., Trachurus mediterraneus, Scomber japonicus and Xiphias gladius each increased in more than seven subareas from 1928-1969 to 1970-2007, depending on the species and gear used. The factors related to such differences are discussed. Keywords: Species composition, long-term trends, multi-gear fisheries, multi-species fisheries, Greek fisheries

1. Introduction Temporal changes in species composition of fisheries landings might reflect the combined effect of fisheries (e.g. Jennings & Kaiser, 1998) and environmental (e.g. Lloret et al., 2001) changes. However, a serious limitation in such studies is their relatively short duration (< 30 years), a common situation in Mediterranean and Greek fisheries (CIESM, 2003). This might mask the between-year variability in species landings. Greek fisheries landings have been collected by various organisations during 1928-2007 (for an extended discussion see Moutopoulos & Stergiou, 2011). Recently, Moutopoulos & Stergiou (in press) reconstruct Greek marine fisheries landings per gear and subarea for the period 1928-2007. Reconstructed landings refer only to commercial landings as they do not include discards, illegal and unreported catches as well as recreational fisheries landings. In the present study, we estimated the historical change in the species composition of the landings in Greek waters per fishing subarea and gear during 1928-2007, in order to identify: (a) critical periods of changes in the representative species; and (b) the spatial variability in species composition in relation to the different gear used. 2. Materials and Methods Species composition of the landings per gear and subarea during 1928-2007 was estimated from the reconstructed landings per species disaggregated for each of the 16 fishing subareas (Fig. 1) and gear (i.e. trawlers, purse-seiners, beach-seiners and small-scale gears) given in Moutopoulos & Stergiou (in press). The reconstruction was based on the landings reported by two organizations: (a) Hellenic Statistical Authority (HELSTAT) that recorded the landings per species/gear/subarea during 1990-2007 but have never been published/presented before (provided to us by Mrs Aik. Nasiakou, HELSTAT) in the annual bulletins; and (b) Agricultural Statistics of Greece that recorded the landings by prefecture from small-scale vessels with engine power < Fig. 1. Map of Greek waters showing the division of the fishing subareas allocated by Hellenic Statistical Authority (legends S3 to S18 each enclosed by lines). Subareas 1 and 2 are outside Greek waters (Atlantic Ocean and North African Mediterranean coasts, respectively). 19 HP during 1974-2007. A complete description of the reconstruction is presented in Moutopoulos and Stergiou (in press). Firstly, in order to identify critical periods of time when significant changes of species composition occurred, a matrix [(rows X columns) comprising the mean (all 16 subareas combined) landing percentages of 69 species (henceforth called species) per year (80 years: 1928-2007) was used. Then, the matrix was

transformed into a triangular matrix of similarities using the Bray-Curtis coefficient. To assess whether groups formed by multivariate analysis differed from each other, a one-way analysis of similarities (ANalysis Of SIMilarities) (Clarke & Gorley, 2001) was used. SIMPER (SIMilarity PERcentages) (Clarke & Gorley, 2001) was used to identify the contribution of each species to the average Bray-Curtis similarity within the groups formed. Secondly, we estimated and compared the species composition of the landings per gear and subarea for the groups of years defined from multivariate analysis. 3. Results 3.1. MULTIVARIATE ANALYSIS The classification of the mean landing percentages of the 69 species per year during 1928-2007 indicated two significant (ANOSIM Global R: 0.91; P<0.001) main groups of years; one for years 1928-1969 and another one for the years 1970-2007 (Fig. 2). SIMPER analysis showed (with decreasing order of importance) that five species contributed more than 58% to the similarity for 1928-1969 (i.e. Sardina pilchardus, Spicara smaris, Engraulis encrasicolus, Boops boops and Trachurus mediterraneus) and eight species (i.e. Sardina pilchardus, E. encrasicolus, other Osteichthyes, B. boops, T. mediterraneus, Merluccius merluccius S. smaris and Mugilidae) during 1970-2007 (Fig. 2). 3.2. SPECIES COMPOSITION OF LANDINGS PER TIME PERIOD AND SUBAREA Percentage differences < -2.5% or > 2.5% of the species composition per fishing subarea and gear between 1970-2007 and 1928-1969 are shown in Table 1. These species contributed 54% of the total landings per gear/subarea combination (with the exception of trawl landings in S16, due to the high percentage of other Osteichthyes landings). Trawlers and small-scale vessels exploited numerous (17 and 22 species, respectively) demersal and benthopelagic species. In contrast, purse-seiners and beach-seiners targeted small- and medium-sized pelagic species (9 and 10 species, respectively) (Table 1). For 58 out of 64 subarea/gear combinations the number of species contributing 90% to the landings per gear/subarea combinations generally decreased from 1928-1969 to 1970-2007. S. pilchardus (for purse-seiners in S3) and Natantia (for trawlers in S4) showed the highest percentage decrease (-31.2% and -30.7%, respectively) from 1928-1969 to 1970-2007, whereas E. encrasicolus (for purse-seiners in S4 and S13) showed the highest percentage increase (24.2% and 26.8%, respectively) from 1928-1969 to 1970-2007 (Table 1). S. smaris (for all gears), Sardinella aurita (for purse-seiners), S. pilchardus (for purse-seiners, beach-seiners and small-scale vessels), Mullus surmuletus (for trawlers and small-scale vessels) and Sarda sarda (for purse-seiners, beach-seiners and small-scale vessels) decreased in more than six subareas from 1928-1969 to 1970-2007, depending on the species. In contrast, B. boops (for purse-seiners and beach-seiners), E. encrasicolus (for purse-seiners), M. merluccius (for trawlers and small-scale vessels), Mugilidae (for small-scale vessels), Octopus vulgaris (for small-scale vessels), Thunnus spp. (for

small-scale vessels), T. mediterraneus (for purse-seiners and beach-seiners), Scomber japonicus (for purse-seiners) and Xiphias gladius (for small-scale vessels) all increased in more than seven subareas each from 1928-1969 to 1970-2007, depending on species (Table 1). Fig. 2. Dendrogram (group-average clustering) of the species (69 species) composition landings for all gears combined per year (during 1928-2007) based on Bray-Curtis similarities (%), Greek waters, 1928-2007 and percentage contribution of each species to the average Bray-Curtis similarity within each of the groups (C%). 4. Discussion The results of the present study refer to the historical evolution of the species composition of the landings in Greek waters per fishing subarea and gear during an 80-year period, 1928-2007. During this period the following developmental phases of the Greek fisheries have been identified: pre-development phase (1928-1946), growth phase (1947-1969), fully to overexploited phase (1970-1994) and collapse phase (1995-2007) (Moutopoulos & Stergiou, 2011, modified from Hilborn & Walters, 1992). Species composition changes between 1928-1969 and 1970-2007 might be related to the combined effect of several factors. In particular, the modernization of the Greek fisheries changed

the fishing operational activities since 1970. During 1928-1969, each gear exploited the shallower water depth zone (< 200 m) and targeted the species limited to this zone, such as Spicara smaris, S. maena (Froese & Pauly, 2011), Mullus barbatus, M. surmuletus (e.g. Tserpes et al., 2002) and Pagellus erythrinus (e.g. Tserpes & Peristeraki, 2002; Labropoulou et al., 2008). However, after the entrance of Greece to European Union (1981), funding oriented to the fisheries sector triggered the modernization of Greek fisheries towards the: (a) spatial expansion of operational activities from 200 m (Ananiadis, 1984) to more than 400 m (Anonymous, 2001); and (b) increase the fishing time on annual basis from 150-170 fishing days in 1938 (Ananiadis, 1970) to about 240 fishing days in the late 1990s (Anonymous, 2001). These changes led, especially for trawl and small-scale fisheries, to the engagement to the large pelagic (i.e. Thunnus spp., X. gladius) and deep water fisheries (e.g. Lophius spp. landings for trawlers and small-scale vessels and Dentex macrophthalmus and Polyprion americanus for small-scale vessels). The same has been also observed from field studies in Greek waters during the last decade (Anonymous, 2001; Politou et al., 2003). Notable exception from the above-mentioned pattern was the case of beach-seiners that was gradually withdrawn since 1980 (Papaconstantinou & Farrugio, 2000) till its complete banning in 2013 (ER 1967/2006). In addition, since 1953 various technical measures were gradually established in Greek fisheries legislation (Moutopoulos & Stergiou, 2011) that also changed the operational activities in Greek fisheries. For instance, until 1967 trawlers were allowed to fish species such S. smaris, using a trawl-net with electric light, a technique similar to that used by purse-seiners to catch small-pelagics (Ananiadis, 1968). During the same period, midpelagic trawl, targeting small-pelagics was also operating in Greek waters and its landings might be probably included together with the trawl landings. However, since 1967 both fisheries were prohibited by national law (R.D. 917/66; P.D. 244/21-6-91, respectively). Market aspects might also be responsible for changes related with E. encrasicolus S. pilchardus landings during the last 80 years. Since 1970 fisheries are gradually oriented more on E. encrasicolus rather than S. pilchardus, possibly because of the higher prices for the former species (Stergiou, 1989). Finally, eutrophication changes, originated either from large scale and/or localized effects, generally enhance fisheries productivity, especially for small-pelagics (e.g. B. boops, E. encrasicolus, S. smaris) (Caddy & Garibaldi, 2000) in certain subareas (i.e. S4, S10, S13, S14). The latter case requires the combined analysis of species landings and primary productivity estimates that is outside the scope of the present study. 6. References ANANIADIS, K.I. 1968. Greek fisheries. Prospects and perspectives of development. Athens, Centre of National Programme & Economic Research, 281 pp. Ananiadis, K.I. 1970. The effects of trawl fishing on the stocks of different commercial species in Greek waters. Proceedings of the Hydrological Institute of Athens Academy, pp. 493-497. ANANIADIS, K.I. 1984. History of Fishery. Athens, 222 pp. (Reprint from Marine Encyclopedia, 1962. Athens, 450 pp.). ANONYMOUS, 2001. Patterns and propensities in Greek fishing effort and catches. Report to the EU (DGXIV), Project 00/018, 36 pp + 179 pp appendices.

Caddy, J.F. & Garibaldi, L., 2000. Apparent changes in the trophic composition of world marine harvests: the perspective from FAO capture database. Ocean & Coastal Management, 43: 615-655. CIESM, 2003. Mediterranean biological time series. Workshop Series, Split, 11-14 June 2003. CLARKE, K.R. & GORLEY, R.N., 2001. Primer v5: User Manual/Tutorial. Primer-E: Plymouth, 91pp. Jennings, S. & Kaiser, M.J., 1998. The effects of fishing on marine ecosystems. Advance Marine Biology, 34: 201-352. HILBORN, R. & WALTERS, C.J., 1992. Quantitative fisheries stock assessment. New York, Chapman & Hall, 570 pp. Froese, R. & Pauly, D., 2011. FishBase. World Wide Web electronic publication. www.fishbase.org. version (2/2011). Labropoulou, M., Damalas, D. & Papaconstantinou, C., 2008. Bathymetric trends in distribution and size of demersal fish species in the north Aegean Sea. Journal of Natural History, 42(5-8): 673-686. Lloret, J., Lleonart, J., Sole, I. & Fromentin, J.M., 2001. Fluctuations of landings and environmental conditions in the north-western Mediteranean Sea. Fisheries Oceanography, 10(1): 33-50. Moutopoulos, D.K. & Stergiou, K.I., 2011. The evolution of Greek fisheries during 1928-1939. Acta Adriatica, 52(2). Moutopoulos, D.K. & Stergiou, K.I., in press. Spatial disentangling of Greek fisheries landings by gear during 1928-2007. Journal of Biological Research. Papaconstantinou, C. & Farrugio, H., 2000. Fisheries in the Mediterranean. Mediterranean Marine Science, 1(1): 5-18. Politou, C.Y., Kavadas, S., Mytilineou, C., Tursi, A., Carlucci, R. & Lembo, G., 2003. Fisheries resources in the deep waters of the eastern Mediterranean (Greek Ionian Sea). Journal of Northwest Atlantic Fisheries Society, 31: 35-46. Stergiou, K.I., 1989. A seasonal autoregressive model of the anchovy Engraulis encrasicolus fishery in the Eastern Mediterranean. Fisheries Bulletin, 88: 411-414. Stergiou, K.I., Christou, E.D., Georgopoulos, D., Zenetos, A. & Souvermezoglou, C., 1997. The Hellenic Seas: Physics, Chemistry, Biology and Fisheries. Oceanography and Marine Biology: an Annual Review, 35: 415-538. Tserpes, G., Fiorentino, F., Levi, D., Cau, A., Mureni, M., Zamboni, A. & Papaconstantinou, C., 2002. Distribution of Mullus barbatus and Mullus surmuletus (Osteichthyes: Perciformes) in the Mediterranean continental shelf: implications for management. Scientia Marina, 66(Suppl. 2): 39-54. Tserpes, G. & Peristeraki, P., 2002. Trends in the abundance of demersal species in the southern Aegean Sea. Scientia Marina, 66(Suppl. 2): 243-252.

Table 1: Percentage difference (< -2.5%, > 2.5%) of the species composition between 1970-2007 and 1928-1969 per gear and subarea (S), Greek waters, 1928-2007. Bold values indicated the highest (+/-) changes in each gear-subarea combinations. Numbers indicated mean (±SE) % contribution of total (i.e. all species combined) landings per subarea. * indicated high contribution (>10%) of other Osteichthyes landings. Trawlers S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 B. boops 4.3 9.1 5.0 E. encrasicolus -14.7 4.6 Lophius spp. 3.4 5.6 2.7 M. merluccius 8.6 16.5 3.1 5.3 4.9-6.9 4.1 4.9 5.1 7.2 5.5 M. poutassou 4.0 5.4 3.8 3.3 3.4 M. barbatus -11.8 M. surmuletus -3.1-3.3-3.5-5.9 N. norvegicus 5.5 Octopodidae -3.0-14.5-3.0-6.6 P. kerathurus 4.1 7.6 S. sarda -14.6 S. pilchardus -3.6-2.8-4.3 S. officinalis -3.1-11.7-5.2 S. flexuosa -12.3-3.6 S. smaris -4.9-11.6-26.0-13.5-5.8-4.1-14.8-14.2-9.0-13.3-4.5-11.5 Squalidae -6.7-10.3 T. mediterraneus 7.6 4.8 Mean % 28-07 73.4 79.5 67.7 80.4 96.2 66.9 77.2 63.0 78.7 58.9* 65.6* 60.3* 76.6 36.9* 54.0* 78.2 Purse-seiners S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 B. boops 5.3 4.6-14.4 4.3 4.5 15.1 E. encrasicolus 18.1 24.2 9.3-12.0 3.0-3.9 23.6 26.8 22.2 6.1 S. sarda -8.0-7.3-10.4-3.0-16.8 S. pilchardus -31.2-26.4-18.8 9.6 4.6 3.4-5.4 3.0 5.9 2.6-16.6-15.4-9.9-3.7-3.9 S. aurita -4.7-5.8-4.1-2.8-11.0-3.8-3.0-4.0-5.6-5.9-4.4 S. japonicus 8.8 6.8 3.4 7.9 3.3 2.6 3.2 2.7 4.0 14.8 3.5 6.7 S. smaris -3.9-7.9-11.9-2.8-4.8-2.7-3.4-6.4-6.7 Thunnus spp. 2.8 7.1 3.0 T. mediterraneus 3.1 3.3 9.6 6.4 2.9-4.2 6.0 Mean % 28-07 91.2 95.2 89.8 91.7 94.7 91.2 97.3 88.3 94.2 89.3 92.8 90.5 88.8 79.8 85.2 84.7 (to be concluded)

Table 1: (concluded) Beach-seiners S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 B. boops 15.1 2.9 3.3 3.1 5.2 5.4 3.5 3.3 6.1 7.9 4.5 8.8 E. encrasicolus 2.7 10.1 9.3 4.9 M. merluccius 5.2 S. sarda -2.6-3.3-3.6-21.3-2.6 S. pilchardus -7.2-5.8-3.3 4.7 2.6-3.7 6.9 6.9 5.2 S. aurita -3.4-3.0-2.9 S. japonicus 2.9 3.0 S. officinalis -4.0-3.6 S. smaris -13.9-15.2-20.5-9.9-16.5-9.0-16.6-16.3-13.1-23.0-26.4-18.7-15.6-12.9-11.6 T. mediterraneus 4.9 4.3 2.7 2.7 2.8 Mean % 1928-2007 88.9 93.9 72.6 89.9 89.5 79.6 78.7 76.9 85.5 71.0 75.2 64.6 87.5 84.9* 83.9 72.6 Other small-scale S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 B. boops -6.8-4.2 2.9-5.3-6.3 D. macrophthalmus 4.6 2.9 4.8 3.1 17.3 D. labrax 7.1 7.9 4.5 9.2 E. encrasicolus -14.5 3.0 5.2 Lophius spp. 6.1 7.5 4.2 6.9 M. merluccius 5.6 7.6 4.3 7.9 4.7-5.2 3.5-4.4 2.7 8.2 3.2 Mugilidae -14.4-13.5 4.1 10.4 8.8 7.7 4.7 8.0 12.4 M. barbatus -5.5-2.6 M. surmuletus -4.0-11.1-6.4-3.8-4.6-6.0-6.8-6.6 O. vulgaris 3.4 4.1 3.6 4.0 3.6 2.5 3.3 2.7 8.6 15.2 2.7 3.2 P. erythrinus -2.7-3.2-3.2-3.0 4.1 3.0-2.8 P. pagrus -5.0-3.1-5.1 P. americanus -3.4-3.8-2.6 7.9 S. sarda -2.9 6.6-4.1-22.8-14.8-2.9 5.3-9.1 S. pilchardus -9.4-11.4-11.7-8.5-4.2 12.7-5.3 S. aurita -8.6-2.6 S. officinalis -6.5-3.8 2.6 4.3-7.2-11.6 S. flexuosa -3.4-5.3-4.2 S. smaris -2.7-10.6-10.8-9.1-5.5-7.3-5.8-4.7-9.5-11.7-7.2-5.9-3.9 Squalidae -5.1-4.8-5.8-10.8 Thunnus spp. 4.7 3.6 3.8 4.5 4.1 4.6-4.1 X. gladius 9.1 10.9 11.2 10.7 3.1 6.3 5.2 3.0 9.7 Mean % 1928-2007 56.1* 59.0* 58.2 56.0* 64.2 61.7 62.7 69.6 73.6 65.7 60.4* 70.3 72.0 61.3 57.7* 68.5*