Eastern mediterranean sea

Abstract: Data used to produce figures come from the STECF working group on Fisheries Dependent Informations . Please not that time series might be incomplete for some countries/indicators.

Landings

The Eastern Mediterranean (EM) case study will focus in the Aegean Sea which is one of the major basins of the Eastern Mediterranean Sea, covering an area of 240,000 km2. Its coastline is very irregular and its topographic structure very complicated. It corresponds to the General Fisheries Commission for the Mediterranean (GFCM) statistical grid system for Aegean Sea, Geographical Sub-Area (GSA) 22. FAO has also defined Aegean Sea as Division 3.1 of Eastern Mediterranean Sea Subarea 37.3 in Area 37 which refers the Mediterranean and Black Sea as one of the world’s Major Fishing Areas.

The Aegean Sea includes territorial waters of Greece (6 nm), Turkey (6 nm) and international waters. Each fleet operates in its own territorial waters and both operate in international waters. So far, no Exclusive Economic Zone (EEZ) has been declared.

Fisheries in Greek waters are characterized as multispecies and target mainly demersal and pelagic fish stocks. The demersal species such as hake, red mullet, cephalopods and shrimps are mainly caught by trawlers, while small pelagics such as sardine, anchovy, bogue, Mediterranean horse mackerel and other Scombridae are caught by purse seiners. Among highly migratory fish (tuna and tuna like species), the main commercially valuable species are bluefin tuna, swordfish and albacore. About 50 - 60% of total domestic fisheries production in Greece consists of small pelagics. Reported Greek catches amounted to 60,318.7 t in 2014, of which 51,688.7 were in GSA 22.

In more detail, the Greek fleet is comprised of the following segments:

• Small scale vessels, the largest fleet segment of the Greek fishing fleet that uses mainly nets, longlines, pots, and traps (5,361 small vessels 0-6m, 8,310 vessels 6-12m and 163 vessels 12-18m), that captures more than 60 species of fish, shellfish and cephalopods.
• Longliners, with 137 vessels 2-18m, targeting pelagic species such as white sea bream (Diplodus sargus), hake (Merluccius merluccius), common sea bream (Pagrus pagrus), common pandora (Pagellus erythrinus), swordfish and tunas.
• Bottom trawlers have multi-species characteristics, captures numerous fish species, such as red mullets, hake and shrimps. This fleet segment includes 120 active vessels of 18-24m with a total employment that corresponds to 682 FTEs and 167 vessels of 24-40m and 1,007 FTEs.
• Purse seiners, consisted of 87 vessels 12-18m, 134 vessels 18-24m and 31 vessels 24-40m targeting mainly anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Aegean Sea.

In Discardless, we focus on Northwestern (NW) Aegean Sea that includes the Gulfs of Thessaloniki (also known as inner Thermaikos) and Thermaikos as well as the gulfs of Chalkidiki Peninsula. Thermaikos Gulf is the main fishing ground, which is considered one of the most productive in the Greek Seas. Thermaikos Gulf is a shallow water area having a maximum depth of 50 m (Figure 1). Large river systems (Gallicos, Axios, Loudias and Aliakmon) discharge into Thermaikos Gulf about 207m3/s, with significant temporal variability. Reported catches in 2014 for Thermaikos Gulf and Gulf of Chalkidiki were 11,212.8 t.

Proportion of landings in each rectangle

Landing 2004-2014

[STECF MED & BS data (2015)]

Landing 2013

[STECF MED & BS data (2015)]

Landings 2014

[STECF MED & BS data (2015)]

Trends in landings by gears

[STECF MED & BS data (2015)]

Average Landings by gears

Years 2004-2014

[STECF MED & BS data (2015)]

Year 2013

[STECF MED & BS data (2015)]

Year 2014

[STECF MED & BS data (2015)]

Trends in landings

By vessel length

[STECF MED & BS data (2015)]

By countries

[STECF MED & BS data (2015)]

Average Landings by countries

Years 2004-2014

[STECF MED & BS data (2015)]

Year 2013

[STECF MED & BS data (2015)]

Year 2014

[STECF MED & BS data (2015)]

According to the Fleet Register (KAM 2014), in 2014, 1460 vessels were registered in 7 ports of Thermaikos Gulf (Thessaloniki: 739 vessels; Skala Katerinis: 251 vessels; Nea Moudania: 232 vessels; Nea Michaniona: 82 vessels; Platamonas: 71 vessels; Agiokampos: 66 vessels; Stomio: 19 vessels). Based on the main gear used, 58 of these vessels are trawlers (using bottom trawls, OTB), 29 are purse seiners (using purse-seines, PS) and 1373 are small-scale coastal vessels using a variety of fishing gears. The percentage of active vessels to the total will be determined within the framework of this project.

Following Thracian Sea, Thermaikos Gulf concentrates the second highest fishing effort of trawlers in the Aegean Sea (GSA 22). In total, 47.6% of trawling in the Aegean takes place in Thermaikos Gulf and Thracian Sea. As far as purse-seiners are concerned, 20.23% of purse-seining in the Aegean Sea (GSA 22) takes place in Thermaikos Gulf.

Average Landings by species

Years 2004-2014

[STECF MED & BS data (2015)]

Year 2013

[STECF MED & BS data (2015)]

Year 2014

[STECF MED & BS data (2015)]

Trends in landings by species

[STECF MED & BS data (2015)]

Discards

Causes of discarding

All métiers used in Thermaikos Gulf share the same market and regulation causes for discarding. The general fisheries regulations for the Greek seas, based on the European legislation, apply in Thermaikos Gulf. For example, Minimum Landing Size (MLS) is the main reason for discarding hakeMerluccius merluccius, red mullet Mullus barbatus and cuttlefish Sepia spp., while low market demand is the reason of discarding spottail mantis shrimp Squilla mantis and other crustaceans. Discarding practices are influenced by fishing processes and fishers’ decision making, which, at least in Greek waters, is affected by several factors, including weather conditions, economic pressure, market demands, fishing strategies, skipper’s knowledge and skills (Tsitsika and Maravelias 2006).

Based on the classification by Eliasen and Christensen (2012), the factors affecting discards in the Mediterranean may be divided into four categories: (a) natural conditions that include species composition and abundance, resource availability, species invasions, and environmental factors (depth, seabed, productivity); (b) community (haul duration, sorting practices, soak time); (c) states and regulations that include technical measures (gear selectivity), spatiotemporal closures, MLS, control mechanisms; and (d) market influence that includes economic value of species (damaged, unwanted catch), resource use related to socio-economic factors, storage capacity of the vessel and sortingcapacity of the crew (Eliasen and Christensen 2012). These factors often act in synergistic manner that may not be straightforward to disentangle, especially in multispecies fisheries, which is the case in the Mediterranean (Tsagarakis et al. 2014). As a result, high regional, seasonal, and interannual fluctuations are observed even within the same fishing gear (Tsagarakis et al. 2014).

Effects of discarding

The survival rates of discards have not been evaluated in the northern Aegean Sea. With the exception of some species, survivability is considered to be very low in the area. There is a study on the survival rates of three fish species, the brown comber (Serranus hepatus), black goby (Gobius niger) and annular seabream (Diplodus annularis), after their escape from a 40 mm stretched diamond mesh polyethylene (PE) codend that has been conducted in eastern Aegean Sea (Duzbastilar et al. 2010). With very short (15 in duration) hauls, the mean survival mean survival percentages of open codend and experimental cages were found to be 97.1% and 98.3% for brown comber, 69.0% and 77.2% for black goby, and 97.5% and 98.6% for annular seabream respectively. The “Choke effect” is not applicable in any of Thermaikos Gulf fisheries because, contrary to several north Atlantic fisheries, there are no quota restrictions in the study area.

Although the ecological effects of discards have not yet been evaluated in Thermaikos Gulf, the cascading effect across the marine food wed is expected to be high (e.g. seabirds: Arcos and Oro 2002) at all level of biological organization (Sarda et al. 2015). Data on the effect of purse-seine discards exists only for Thracian Sea (Tsagarakis et al. 2012), while the general effects of discards have been recently reviewed (Tsagarakis et al. 2014).The potential impacts of discard landing obligation may be dramatic for theMediterranean Sea,where a large part of discards is already composedof juvenile fishes with body sizes smaller than theminimum landing sizes and of invertebrates (Sarda et al. 2015).

The economic, operational and technical costs associated with the manipulation and storage of discards on board may be high (Sarda et al. 2015). These costs may include additional crew and storage costs and landings costs (boxes, storage, ice). The monitoring and controlling costs to prevent fishers from discarding when at sea are also expected to be high (Sarda et al. 2015).

Catches (Landings+Discards)

[STECF MED & BS data (2015)]

Disclaimer : Following graphs are made using discards rates at high spatial level and the landings at statistical rectangle level as raising factor. We assume that it's not the more statistically consistent way to proceed. However we consider that, with available data, it's a first step to use the data.

Discards by species

Year 2013

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Year=2014

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Discards by Species for most important gears (year=2014)

Second Gear (GNS)

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Third Gear (GTR)

[STECF MED & BS data (2015) for landings and National Data for discards rate]

First Gear (in terms of total discards) (OTB)

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Trends in discards by Country (5 most important countries in Landings)

Total Discards

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Discards ratio (Discards/(landings+discards))

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Trends in discards by Gear (5 most important Gear in Landings)

Total Discards

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Discards ratio (Discards/(landings+discards))

[STECF MED & BS data (2015)for landings and National Data for discards rate ]

The most abundant species in the bottom trawl catches in Thermaikos Gulf are red mullet Mullus barbatus, cuttlefish Sepia spp., spottail mantis shrimp Squilla mantis, caramote prawn Melicertus kerathurus, deep-water rose shrimp Parapenaeus longirostris, musky octopus Eledone spp., anglerfish Lophius spp., European hake Merluccius merluccius, spotted flounder Citharus linguatula, and octopus Octopus spp. (Apostolidis et al. 2013). Red mullet Mullus barbatus and surmullet Mullus surmuletus, caramote prawn, deep-water rose shrimp, European hake, cuttlefish and octopus are the main target species of the trawl fishery in Thermaikos Gulf.

Overall 191 species (137 fishes, 29 crustaceans and 25 cephalopods) were collected in the northern Aegean Sea by the experimental bottom trawl survey (MEDITS) in 2013 (DCF dataset). Species with the highest biomass (kg/km2) rates were: European anchovy Engraulis encrasicolus (220.32 kg/km2), Illex coindetti (87.95 kg/km2), European sardine Sardina pilchardus (51.43 kg/km2), blue whiting Micromesistius poutassou (38.03 kg/km2), Atlantic horse mackerel Trachurus trachurus (34.06 kg/km2), European hake Merluccius merluccius (31.72 kg/km2), deep-water rose shrimp Parapenaeus longirostris (25.44 kg/km2), red mullet Mullus barbatus (24.05 kg/km2), argentine Argentina sphyraena (23.39 kg/km2) and silver scabbardfish Lepidopus caudatus (23.22 kg/km2).

Anchovy Engraulis encrasicolus, sardine Sardina pilchardus and Atlantic chub mackerel Scomber colias are the main target species of purse seines in the area.

The small-scale coastal fleet of Thermaikos Gulf targets a wide variety of species some of which are also targeted by the trawling fleet (e.g. red mullet and surmullet, and caramote prawn) and one by the purse seiners (European sardine).

The discarded species and the discards (D) to catch (C) ratio per gear and species in northern Aegean Sea (data from DCF 2013) are shown in Table 4.Onboard observations to all gears/vessels were confined to the last trimester of 2013 (October to December).

According to recent research in Thermaikos Gulf (Apostolidis et al. 2013), in which samples were collected between November 2012 and March 2013, trawl discard to catch ratios in Thermaikos Gulf are different (Table 5) compared to those reported by DCF, indicating a potential seasonal effect (Tsagarakis et al. 2014).

Trends in discards by Gear (5 most important species in Landings)

Total Discards

[STECF MED & BS data (2015) for landings and National Data for discards rate]

Discards ratio (Discards/(landings+discards))

[STECF MED & BS data (2015)]

En savoir plus

Apostolidis C, Karachle PK, Maravelias CD (2013)Bottomtrawl discarding rates and practices in Thermaikos Gulf (NW Aegean Sea):preliminary results.Hellenic Conference of Ichthyologists15: 25-28

Arcos JM, Oro D(2002) Significance of nocturnal purse seine fisheries for seabirds: a case study off the Ebro Delta (NW Mediterranean). Marine Biology141: 277-286.

Duzbastilar FO, Aydin C, Metin G, Lok A, Ulas A, Ozgul A, Gul B, Metin C, Ozbilgin H, Sensurat T, Tocac A (2010) Survival of fish after escape from a 40 mm stretched diamond mesh trawl codend in the Aegean Sea. Scientia Marina74: 755-761

EC (2008) Council Regulation (EC) No 199/2008 of 25 February 2008 concerning the establishment of a Community framework for the collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy.

Eliasen S, Christensen A-S(2012) The institutional basis fordiscard behaviour. The Badminton project: report in theBadminton project work package 4: Socio-economic and institutionalincentives for discarding. 16 pp.

Kallianiotis AA, Vidoris P, Sylaios GK (2004)Fish species assemblages and geographical sub-areas in the North Aegean Sea, Greece. Fisheries Research68: 171-187

Sarda F, Coll M, Heymans JJ, Stergiou KI (2015) Overlooked impacts and challenges of the new Europeandiscard ban. Fish and Fisheries16: 175–180

Tsagarakis K, Vassilopoulou V, Kallianiotis A, Machias A(2012)Discards of the purse seine fishery targeting small pelagic fish in theEastern Mediterranean Sea. Scientia Marina76: 561–572

Tsagarakis K, Palialexis A, Vassilopoulou V (2014) Mediterranean fishery discards: reviewof the existing knowledge.ICES Journal of Marine Science71: 1219-1234

Tsitsika EV, Maravelias CD(2006) Factors affecting purse seine catches: an observer-based analysis. Mediterranean Marine Science7: 27-40

Citation :

Fiche Eastern mediterranean sea, Author(s) : Ioanna Argyrou and George Triantaphyllidis


DiscardLess Atlas [on line]. 2017. Guitton J., Ulrich, C., Vermard Y., Afonso P., Andonegi E., Argyrou I., Calderwood J., Fauconnet L., Quetglas A., Morato T., Prellezo R., Robert M., Savina-Rolland M., Triantaphyllidis G., Vaz S.
http://www.discardless.eu/atlas/