ΑΛΙΕΥΤΙΚΗ ΠΑΡΑΓΩΓΗ 5 ΕΙΔΩΝ ΨΑΡΙΩΝ ΑΝΑ ΑΛΙΕΥΤΙΚΟ ΕΡΓΑΛΕΙΟ ΣΤΙΣ ΚΥΚΛΑΔΕΣ ΤΗΝ ΠΕΡΙΟΔΟ 1928-2007 Μουτόπουλος Δ.Κ. 1,2, Στεργίου Κ.Ι. 2 1, 2 ΤΕΙ Μεσολογγίου, Τμήμα Υδατοκαλλιεργειών & Αλιευτικής Διαχείρισης, dmoutopo@teimes.gr 2 Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης, Τμήμα Βιολογίας, Τομέας Ζωολογίας, Εργ. Ιχθυολογίας, Θ. 134, 541 24 Θεσσαλονίκη, kstergio@bio.auth.gr Περίληψη Στην παρούσα εργασία παρουσιάζεται η αλιευτική παραγωγή πέντε ειδών ψαριών (Diplodus annularis, Merluccius merluccius, Mullus surmuletus, Scorpaenidae και Serranus cabrilla) ανά αλιευτικό εργαλείο (μηχανότρατα, γρι-γρι, βιντζότρατα και άλλα παράκτια εργαλεία) για την περιοχή των Κυκλάδων την περίοδο 1928-2007. Η ανασύσταση των δεδομένων της παραγωγής βασίστηκε στα αδημοσίευτα δεδομένα της Ελληνικής Στατιστικής Αρχής (ΕΛΣΤΑΤ) ανά είδος, υποπεριοχή και αλιευτικό εργαλείο για την περίοδο 1990-2007 και τα δεδομένα που προέρχονται από τη μικρή παράκτια αλιεία ανά παράκτιο νομό που καταγράφονται από τη Γεωργική Στατιστική της Ελλάδας για την περίοδο 1970-2007. Τα πιο αντιπροσωπευτικά είδη διέφεραν ανά εργαλείο, όπου το μεγαλύτερο ποσοστό της παραγωγής στη μηχανότρατα να αποτελείται από την κατηγορία των «διάφορων ειδών ψαριών», στα γρι-γρι από τα είδη Boops boops, Trachurus mediterraneus και Scomber japonicus, στις βιντζότρατες από το είδος Spicara smaris και στα άλλα παράκτια εργαλεία από τα είδη B. boops, M. surmuletus και M. merluccius. Η ανασυσταμένη παραγωγή για τα πέντε είδη που μελετήθηκαν παρουσίασε αύξηση για την περίοδο 1928 έως τα τελευταία χρόνια των δεκαετιών του 80 και του 90, ανάλογα με το είδος και το αλιευτικό εργαλείο, ενώ για τα υπόλοιπα χρόνια μέχρι το 2007 εμφάνισε μείωση. Εξαίρεση αποτέλεσε η παραγωγή του είδους D. annularis, για την οποία παρατηρήθηκε αύξηση στα αλιεύματα της μηχανότρατας και των άλλων παράκτιων εργαλείων. Λέξεις κλειδιά: Ανασύσταση αλιευτικής παραγωγής, μακροχρόνιες τάσεις, πολύ-ειδική αλιεία, Κυκλάδες, Μεσόγειος. LANDINGS PER FISHING GEAR FOR FIVE FISH SPECIES IN CYCLADES (AEGEAN SEA) DURING 1928-2007 Moutopoulos D.K. 1,2, Stergiou K.I. 2 1,2 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, fisheries landings of five fish species (i.e. Diplodus annularis, Merluccius merluccius, Mullus surmuletus, Scorpaenidae and Serranus cabrilla) caught by different gear in Cyclades were reconstructed and presented for 1928-2007. The reconstruction was based on the available data landings per species, gear (i.e., trawlers, purse-seiners, beach-seiners and other small-scale vessels with engine power 19 HP ) and subarea during 1990-2007 that have been recorded by Hellenic Statistical Authority but have never been published/presented before, and the data landings derived from small-scale vessels (i.e. with engine power < 19 HP) per coastal prefecture that have been reported by Agricultural Statistics of Greece during 1970-2007. The species dominating the landings in Cyclades varied with gear, with trawl landings mostly represented by the other Osteichthyes group, purse-seine landings by Boops boops, Trachurus mediterraneus and Scomber japonicus, beach-seine landings by Spicara smaris and those of small-scale vessels by B. boops, M. surmuletus and M. merluccius. The reconstructed landings for the five studied species increased from 1928 up to the late 1980s-late 1990s, depending on species/gear, and then declined for the remaining years, with the exception of those for D. annularis for which trawl and small-scale landings increased during the same period. Keywords: Landing reconstruction, long-term trends, multi-gear fisheries, Cyclades, Mediterranean.
1. Introduction One of the problems when studying the effects of fishing on marine ecosystems is that generally fisheries monitoring takes place well after such impacts started. Shifting the baseline (Pauly, 1995) backwards to the pre-industrialization phase of fisheries using pieces of information (Zeller & Pauly, 2006) is a valuable repository of knowledge (Zeller et al., 2005). The lack of historic fisheries statistics and/or poorly developed data collection systems, that are common in Mediterranean and Greek fisheries (Ciesm, 2003), calls for such a reconstruction. Cyclades (south Aegean Sea) is an excellent case study area for developing and testing methods for data poor fisheries (Stergiou & Tsikliras, 2007) because: (a) is a highly fisherydependent area (Tzanatos et al., 2006); (b) the traditional small-scale fisheries component is strongly represented (Stergiou et al., 2006); and (c) the demand for fish is very high especially in the summer months due to touristic activity. Thus, in the present study our aim was to present the reconstructed landings for five fish species (i.e. Diplodus annularis, Merluccius merluccius, Mullus surmuletus, Scorpaenidae and Serranus cabrilla) caught by the most common fishing gears used (i.e. trawlers, purse-seiners, beach-seiners and small-scale vessels) in Cyclades during 1928-2007. These five species are the Mediterranean case study species used in the FP7 project ECOKNOWS (www.ecoknows.eu), which aims to reduce the uncertainty related to various biological parameters used for management by using Bayesian inference and existing knowledge. This will eventually improve knowledge in fisheries science and management. 2. Materials and Methods In Greece, the first organized effort for the collection of fisheries statistics from marine and freshwater systems was established in 1928 (Moutopoulos & Stergiou, 2011). Since then fisheries statistics have been collected by various organizations (Moutopoulos & Stergiou, in press), with those of the Hellenic Statistical Authority (HELSTAT) being more robust, reliable and consistent (Papaconstantinou et al., 2002, Tsikliras et al., 2007). Moutopoulos and Stergiou (in press) reconstructed the species landings by gear and subarea in order to obtain a continuous time series of marine fisheries landings per gear and subarea during 1928-2007. The reconstructed landings refer only to commercial landings and they do not include discards, illegal, unreported and unregulated catches, as well as recreational fisheries landings. In the present study the landings for five fish species (i.e. Diplodus annularis, Merluccius merluccius, Mullus surmuletus, Scorpaenidae and Serranus cabrilla) caught by gear in Cyclades during 1928-2007 were analysed. The reconstruction was based on the landings per species, gear (i.e., trawlers, purse-seiners, beach-seiners and other small-scale gears operated from vessels with engine power 19 HP; henceforth called large vessels) and subarea (Fig. 1a) during 1990-2007 that have been recorded by HELSTAT but have never been published/presented before in the
annual bulletins and thus were not accessible at large (provided by Mrs K. Nasiakou, HELSTAT). In addition, landings from small-scale vessels operated from vessels with engine power < 19 HP by prefecture reported by Agricultural Statistics of Greece (ASG) were disaggregated for each of the 16 HELSTAT subareas during 1975-2007 and were added to the reconstructed landings derived from large vessels during this period. A complete description of the reconstruction is presented in Moutopoulos and Stergiou (in press). Fig. 1. (a) Map of Greek waters showing fishing subareas (i.e., S3 to S18 indicate the 16 fishing subareas of the Hellenic Statistical Authority, and grey parts indicate the prefectures allocated by the Agricultural Service of Greece), the circle in the map indicate the study area; (b) reconstructed and original total (i.e. all species and gears combined) annual landings (in t) in Cyclades, 1928-2007 (c) total (i.e. all species combined) annual landings (in t) per gear (i.e., trawlers, purse-seiners, beach-seiners and small-scale vessels), in Cyclades, 1928-2007; (d) annual gear contribution (%) of total landings (i.e., all species combined) per gear (mean ±SE % gear contribution), in Cyclades, 1964-2007. 3. Results The total (i.e., all species/gears combined) reconstructed landings in Cyclades (Fig. 1a) increased by 5246 % between 1928 and 2007, ranging between 160 t, in 1928, and 8423 t, in 2007, with a maximum of 33742 t, in 1994 (Fig. 1b). The mean contribution of Cyclades landings was
5.4% (±0.02%) of the total Greek landings during 1928-2007 and 44.2% (±1.8%) of these landings were derived from small-scale vessels. Reconstructed total annual landings for each gear showed a considerable increase in Cyclades during 1928-1994 (Fig. 1c). During 1995-2007, purse-seine, beach-seine and small-scale vessel landings gradually decreased with those of small-scale vessels exhibiting a less pronounce decrease (by 23.8%) than those of the remaining two gears (> 83%). In contrast, trawl landings decreased during 1994-1999 and then increased again almost to the 1994 level (Fig. 1c). The percentage contribution of each gear to the total landings during 1964-2007 is shown in figure 1d. The contribution of purse-seiners and beach-seiners gradually decreased during 1964-2007 (from 26.1% and 21.8% to 5.2% and 3.3%, respectively), whereas those of trawlers decreased during 1964-1993 (from 24.1% to 1.6%) and then increased again to the mid-1960s level (mean % during 1994-2007: 21.8%). With respect to small-scale vessels, the percentage contribution of the landings gradually increased from 28.1%, in 1964, to 55.0%, in 2007, with a maximum of 77.5% in 1991 (Fig. 1d). The species dominating the landings in Cyclades varied with gear (Table 1). Thus, for trawlers, the other Osteichthyes group represented 21.3% of the total landings, followed by Spicara smaris, M. surmuletus, M. merluccius and Trachurus mediterraneus (9.9%, 9.1%, 9.0% and 8.7%, respectively). For purse-seiners, Boops boops, T. mediterraneus and Scomber japonicus represented 66.6% of the total landings, whereas for beach-seiners the same percentage was almost attributed only to S. smaris (67.9%). Finally, for small-scale vessels, B. boops was the most representative species (12.6%), followed by the other Osteichthyes group (10.2%) and, to a lesser extent, by M. surmuletus and M. merluccius (6.9% and 6.1%, respectively). Table 1: Mean species composition (% ± SD%) of the annual landings per fishing gear in Cyclades, 1928-2007. Bold values indicate the most representative species per gear. Species are listed alphabetically (only species with percentages > 3.5% are shown). Species All gears Trawlers Purse-seiners Beach-seiners Small-scale % SD% % SD% % SD% % SD% % SD% Boops boops 14.0 0.05 27.2 0.07 9.3 0.04 12.6 0.05 Gurnards 4.6 0.03 Merluccius merluccius 4.3 0.03 9.0 0.04 6.1 0.03 Mullus barbatus 4.5 0.03 Mullus surmuletus 5.1 0.03 9.1 0.04 6.9 0.03 Other Osteichthyes group 10.3 0.04 21.3 0.06 4.7 0.03 7.3 0.03 10.2 0.04 Pagellus erythrinus 3.6 0.02 Sarda sarda 3.5 0.02 4.0 0.03 5.2 0.03 Sardina pilchardus 4.1 0.03 Scomber japonicus 6.2 0.03 19.2 0.06 Scorpaenidae 3.7 0.02 Spicara smaris 14.7 0.05 9.9 0.04 6.7 0.03 67.9 0.10 5.5 0.03 Spondyliosoma cantharus 3.5 0.02 Thunnus spp. 3.7 0.02 Trachurus mediterraneus 8.5 0.04 8.7 0.04 20.3 0.06 4.4 0.03 Other species 33.4 29.4 13.9 15.5 38.4
The landings of two out of the five studied species, M. merluccius and M. surmuletus, represented a significant part (> 4.27%) of the total landings derived from both trawlers and smallscale vessels in Cyclades, whereas Scorpaenidae landings were mainly derived from small-scale vessels (Fig. 2). The landings of the remaining species contributed less than 2.0% of the total landings per gear. During 1928-2007, the landings of the five studied species per gear exhibited high variability and increased to a maximum during the late 1980s-late 1990s, depending on species/gear combination, and declined thereafter, with the exception of those of D. annularis for all gears (Fig. 2). 4. Discussion Reconstructing fisheries landings back in time and disentangling landings by gear and subarea are useful for evaluating the status of the Greek fisheries at an ecosystem-based context by using various ecological (e.g. Marine Trophic Index: Pauly & Watson, 2005) and fisheries (e.g. catch-effort models: Hilborn & Walters, 1992) indices. The results of the present study showed that the reconstructed total landings in Cyclades as well as those of each gear separately parallels the pattern shown in Moutopoulos & Stergiou (in press) for Greek waters, in which four different phases were identified in the evolution of Greek fisheries (1928-1946: pre-development phase ; 1947-1969: growth phase ; 1970-1994: fully tο over-exploited phase ; 1995-2007: collapse phase ). In addition, the general trends for the study species landings per gear showed an increase from 1928 up to late 1980s - late 1990s, with the exception of those for D. annularis. The general pattern of the landing trends for the different species/gear combinations might be related to the effect of one or more of the following factors during 1928-2007: (a) the historical increase in effort that went along with the fleet modernization in the last decades (e.g. Papaconstantinou & Farrugio, 2000); (b) the geographic/bathymetric expansion of the fisheries because of (a) above (Anonymous, 2001), which is of importance for Cyclades because of its highly narrow continental shelf; (c) the presence of numerous islands a fact that might imply that more than one stock of the less mobile species exist; (d) historical development of a wellorganized transportation system (Ananiadis, 1968) so that landings can be directed to main central areas, especially during the winter time; (e) the gradual withdraw of beach-seiners in Cyclades (a decrease by 27.5% during 1991-2007), a fact that might explain along with other factors the decline in the beach-seine landings of all 5 species during the last years; and (f) climate change (e.g. temperature, wind intensity) that might potentially influence fishing effort by changing the number of days that small scale vessels can work at sea (e.g. Stergiou & Lascaratos, 1997). The high percentage contribution of the small-scale landings in Cyclades, especially during 1990-2007 (mean percentage contribution: 57% ± 0.50%) also highlights the significant importance of small-scale fishery for Greece in general and for Cyclades in particular. It should be also noted that the above-estimated values do not include a significant part of the small-scale
landings that are directed to the local market, hotels and restaurants (Tzanatos et al., 2006), without passing from the wholesale markets. It is quite probable that small-scale landings are highly underestimated and their illegal, unreported and unregulated (IUU) (Tinch et al., 2008) part is probably very high. Thus, increasing the accuracy of landing data with the inclusion of accurate estimates of IUU catches should be the next step in order to better evaluate Greek fisheries resources. Fig. 2. Annual species landings for the studied species per gear (i.e. trawlers, purse-seiners, beach-seiners and small-scale vessels) in Cyclades, 1928-2007. Numbers indicate mean (±SE) % contribution of landings per gear-subarea. 5. Acknowledgements The present study was funded from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n 244706/ECOKNOWS project. However, the paper does not necessarily reflect EC views and in no way anticipates the Commission s future policy in the area.
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