SCRS/2010/072 Collect. Vol. Sci. Pap. ICCAT, 66(4): 1471-1479 (2011)

THE TURKISH SWORDFISH FISHERY

Okan Akyol1, Tevfik Ceyhan

SUMMARY

The swordfish fishery in Turkish waters is carried out by harpoon, longline, pelagic gillnet and purse seine in both the Aegean and the Levantine Seas. This study was carried out at some main fishing ports along the Turkish coasts between August 2008 and April 2010. Recently, about 150 fishing boats, ranging from 6.2 to 36 m LOA and from 9 to 680 hp, from 21 fishing ports are participating in the swordfish fishery from Istanbul to Iskenderun. The lower jaw fork length (LJFL) distribution of 1203 specimens of swordfish ranged from 51 to 242 cm. The average lengths according to fishing gears were 140.8 ±2.8 cm for gillnetting (GN), 85.9 ±1.3 cm for longlining (LL) and 81.3 ±0.7 cm for purse seining (PS). A high percentage (65%) of fish had a LJFL less than 80 cm. Results of the Kruskal-Wallis test indicated that differences among the gear distributions were highly significant (P<0.001). The length-weight relationship for all individuals indicated positive allometric growth (b=3.34).

RÉSUMÉ

L’espadon est capturé, dans les eaux turques, au harpon, à la palangre, au filet maillant pélagique et à la senne à la fois dans la mer Egée et la mer Levantine. La présente étude a été réalisée aux principaux ports de pêche situés sur le littoral de la Turquie entre le mois d’août 2008 et le mois d’avril 2010. Ces derniers temps, environ 150 navires de pêche mesurant entre 6,2 et 36 m de longueur hors-tout et dotés de 9 à 680 CV de puissance motrice, originaires de 21 ports de pêche, ont participé à la pêche de l’espadon d’Istanbul à Iskenderun. La distribution de la longueur maxillaire inférieur fourche (LJFL) de 1.203 spécimens d’espadon a fluctué entre 51 et 242 cm. Selon les engins de pêche, les longueurs moyennes étaient de 140,8±2,8 cm pour le filet maillant (GN), 85,9±1,3 cm pour la palangre (LL) et 81,3±0,7 cm pour la senne (PS). Un pourcentage élevé (65%) de poissons avait une LJFL inférieure à 80 cm. Les résultats du test de Kruskal-Wallis ont indiqué que les différences dans les distributions d’engins étaient très considérables (P<0.001). La relation longueur-poids pour tous les spécimens a indiqué une croissance allométrique positive (b=3.34).

RESUMEN

La pesquería de pez espada en aguas turcas se lleva a cabo mediante arpón, palangre, redes de enmalle pelágicas y cerco, tanto en el mar Egeo como en el mar de Levante. Este estudio se ha realizado en algunos de los principales puertos pesqueros de las costas de Turquía entre agosto de 2008 y abril de 2010. Recientemente, aproximadamente 150 buques pesqueros, de entre 6,2 y 36 m de eslora total y de entre 9 y 680 cv, procedentes de 21 puertos pesqueros, participaban en la pesquería de pez espada desde Estambul a Iskenderun. La distribución de longitud mandíbula inferior a la horquilla (LJFL) de 1203 ejemplares de pez espada oscilaba entre 51 a 242 cm. Las tallas medias según los artes de pesca eran 140,8 ±2,8 cm para las redes de enmalle (GN), 85,9 ±1,3 cm para el palangre (LL) y 81,3 ±0,7 cm para el cerco (PS). Un elevado porcentaje (65%) de peces tenía una LJFL inferior a 80 cm. Los resultados del test de Kruskal-Wallis indicaron que las diferencias entre las distribuciones de los artes eran muy significativas (P<0,001). La relación talla-peso de todos los ejemplares indicaba un crecimiento alométrico positivo (b=3,34).

KEYWORDS

Swordfish, Xiphias gladius, fishery,

1 Ege University Faculty of Fisheries, 35440 Urla, Izmir, Turkey e-mail: [email protected] 1471

1. Introduction

The swordfish (Xiphias gladius) is a commercially important fish in all over the world and it has been exploited since ancient times. Ward et al. (2000) expressed that the swordfish fishing by mostly using harpoon thousands of years ago as near shore subsistence activities in subtropical areas.

The exact time when swordfish fishery starts in Turkey is unknown. However, Turkish swordfish fishery dates back to XVIIth century. In 1630’s, swordfish had been caught via tuna trap nets, deployed along the coast of Beykoz, Istanbul according to “Evliya Çelebi’s Travel Notes” (Kahraman and Dağlı 2008). Quite later, in early 1900’s, Deveciyan (1915), the old director of the Istanbul fish market, stated that the fishing season for swordfish in the Sea of Marmara had been carried out by using harpoon and drift nets in Bosphorus from 15 August to 8 November, and then swordfishes were disappeared due to the colder weather conditions in formerly. Afterwards, Artüz (1963) and Onat (1970) reported that in 1960s, swordfish fishery in the same area was done with gillnet, longline, traps, but mostly by harpoon; the harpooning started in April and it sustained during May and early June, and also gillnetting carried out on moonless nights between September and November in the Bosphorus.

The catch statistics indicated that there were unstable catch amounts between 7 tons in 1976 and 589 tons in 1988 (FAO, 2000). In 2007, the catch amount of swordfish was only 423 t. This is about 3% of total landings from GFCM area. However, swordfish fishing is expanding activity in Turkey. Nowadays, more than 150 fishing boats including albacore boats are participated in swordfish fishery, while there was only about 65 boats in early 2000’s (Ceyhan and Akyol, 2009).

Although the Turkish swordfish fishery is an old activity, there are only a few studies on swordfish’s biology and fishery (Demir et al., 1956; Artüz, 1963; Onat, 1970; Tokaç et al., 1991; Gökoğlu and Oray, 1992; Alıçlı and Oray, 1995, 1996; Öztürk et al., 2001; Akyol et al., 2005, 2008; Erdem and Akyol, 2005; Akyol and Ceyhan, 2007; Alıçlı, 2008; Ceyhan and Akyol, 2009).

After the swordfish fishing in the had been reported by Ceyhan and Akyol (2009), the present paper provides the first comprehensive description of the swordfish fishery in all of Turkish waters.

2. Materials and methods

This study was carried out some main swordfish fishing ports along the Turkish coast between August 2008 and April 2010. The fishery-dependent survey was made with onboard observations. For each fishing boat, the following data by using questionnaire were recorded: (i) the type and technical characteristics of the boat and gears; (ii) fishing areas, periods and fishing methods. Additionally, we interviewed with some old fishermen for historical stories of swordfish.

The measurements (±1 cm LJFL and ±50 g RWT) of swordfish were made in both landing site and wholesale fish market. The length-weight relationship of all individuals was calculated as W=aLb, where W is round weight (g), L is lower jaw fork length (LJFL, cm) and a and b are constants. All of means were given with standard error (±SE).

3. Results

3.1 Fishing ports and grounds

The swordfish fishery in Turkish waters is carried out by harpoon, longline, pelagic gillnet and purse-seine in both Aegean and Levantine Seas. Although, any swordfish existing in the Sea of Marmara, a total of 50 fishing boats from Marmara coasts are participated to swordfish fishery along the Aegean and Levantine coasts. In general, approximately 150 fishing boats from 21 fishing ports are participated to swordfish fishery from Istanbul to Iskenderun (Figure 1).

3.2 Fleet characteristics, fishing gears and seasons

A total of 100 swordfish vessels (67%) were examined and their length of overall (LOA, m), gross tonnage (GT), machine power (hp), age (year), daily fuel consumption (l) and number of personnel were shown in Table 1. Fifteen albacore vessels were also included to fleet. Because, albacore vessels are caught the considerable amount of swordfish as by-catch. At the same time, most of the boats from albacore fleet are usually joined to

1472

swordfish fishery. The fleet was sorted according to fishing gears and the preference of the gears were ordered as gillnet (30%), both gillnet and longline (24%) and harpoon (21%), respectively (Figure 2).

3.2.1 Harpooning Harpooning involves stalking via sighting platform a swordfish that is basking at the sea surface, and then spearing it with a 3-4 m long harpoon with a metal heads attached to a rope. Harpooning started in early 1950’s in the Bosphorus and pair metal heads harpoon, which was invented by fisherman A. Torlak in Poyrazköy (Istanbul), was replaced of the single metal head in a short time (T. Torlak, pers.comm.) and currently, the pair metal heads harpoon is still used by fishermen from Marmara and Gökçeada Islands. Although there is a small portion of catch in limited season, fishermen explain to this method as a hobby. Harpooning is an excitement activity for them. While, harpooning for swordfish in Bosphorus and whole of Marmara Sea was effectively being used until 1970’s, but nowadays, the Saroz Bay is the unique harpooning area. Thirty boats from Marmara and Gökçeada Islands are hunting with harpoon in Saroz Bay between April and June.

3.2.2 Longlining Longlining in the Sea of Marmara was used between early 1960’s and 1975 (R. Ertaş, pers.comm.). In 1974, longlining started in Fethiye (SE Aegean Sea) and this longlines with 30-40 hooks had been used as stable until 1986. The fishermen have been using drifting longlines at the deeper zones since then (O. Somyürek, pers. comm.).

Currently, longlining is usually used during autumn and winter months when not in use of the nets. Ozdere, Datça, Selimiye and Fethiye are the main longliners’ ports. A total of 40 boats are deployed its longlines off Kuşadası, Gökova and Yeşilova Bays and open seas of Fethiye between December and May.

The non-target catches from swordfish longlining are as follows: bluefin tuna (Thunnus thynnus), Atlantic black skipjack (Euthynnus alletteratus), Mediterranean spearfish (Tetrapturus belone), bullet tuna (Auxis rochei), oilfish (Ruvettus pretiosus) and some sharks.

3.2.3 Gillnetting Between early 1900’s and end of the 1950’s, the cotton gillnets had about 110 m length and this gillnets were using in Bosphorus by 20-25 boats in moonless nights of summer months (N. Taşcı, pers. comm.).

Pelagic gillnetting has currently been tended to decrease due to banning since 2006. However, most of fishermen have made some modifications in their nets and put some weights and buoys on both sides of the nets in order to get out of scope of conventional drift net definition in Notification 2/1 Regulating Commercial Fishing. A sample modified net (Figure 3) was made of multifilament polyamide (PA) netting yarn, 23 tex/54 no rope thickness, 440 mm mesh size and 50 meshes depth for lower swordfish part, while 23 tex/18 no rope thickness, 85 mm mesh size and 20 meshes depth for upper part. A total of 30 plastic buoys (10 no) were attached head (upper) rope. Total length of these nets was 2325 m.

There are 22 boats in Babakale and Sivrice ports for gillnetting. Some of the boats in these ports usually go to the coast of Doğanbey Bay for swordfish gillnetting. The fishing season is between May and September. Some boats from Fethiye and Kaş fishing ports are also used the pelagic gillnetting between April and July. This fishery is also spreaded eastwards to Gulf of Antalya for albacore (T. alalunga). Totally 40 vessels are using pelagic gillnets in this area. Especially, the vessels from Istanbul (Rumelifeneri, Poyrazköy) and Kaş, Alanya, Gazipaşa, Karataş, Iskenderun are joined in this region both albacore and swordfish fishery between mid May and mid July.

The non-target catches from swordfish gillnetting are as follows: bluefin tuna (T. thynnus), albacore (Thunnus alalunga), Atlantic black skipjack (E. alletteratus), Mediterranean spearfish (T. belone), bullet tuna (A. rochei), dolphinfish (Coryphaena hippurus), manta ray (Mobula mobular), sunfish (Mola mola), blackfish (Centrolophus niger), pelagic stingray (Dasyatis violacea), blue shark (Prionace glauca), tope shark (Galeorhinus galeus), sandbar shark (Carcharhinus plumbeus), striped dolphin (Stenella coeruleoalba), bottlenose dolphin (Tursiops truncatus), Risso’s dolphin (Grampus griseus) and loggerhead sea turtle (Caretta caretta).

3.2.4 Purse seining Although, purse seiners do not target the swordfish, sometimes young swordfish aggregated with sardine and anchovies under the light boats of purse seiners can also be caught incidentally. This fishery is sustained between

1473

September and April, and juvenile swordfish especially comes from Dikili and Çandarlı Bays, off Karaburun, Çeşme, Didim and Bodrum.

According to fishing methods, the histories of Turkish swordfish fishery above were summarized in Table 3.

3.3 Length distribution and length-weight relationship of swordfish

A total of 1203 specimens of swordfish were measured during the study period. Length-frequency indicated that the length distribution of swordfish was ranged from 51 to 242 cm. The average lengths according to fishing gears were 140.8 ±2.8 cm for gillnetting (GN), 85.9 ±1.3 cm for longlining (LL) and 81.3 ±0.7 cm for purse- seining (PS) (Table 3). The high percentage (65%) of fish had a LJFL less than 80 cm and LL and PS were responsible from this phenomenon (Figure 4). Results of the Kruskal-Wallis test indicated that differences among the gear distributions were highly significant (KW=525.9, P<0.001).

Length-weight relationship in all fish indicated positive allometric growth (b=3.34) (Figure 5).

4. Discussion and conclusion

Currently, the swordfish fishery in Turkish waters is carried out by harpoon, gillnet and longline in both Aegean and Levatine seas. Some swordfish is also caught incidentally by purse-seiners. According to Turkish fishery regulation circular (TFRC), the seasonal closure for swordfish fishery is between Oct, 15 and Nov. 30 in all of Turkish territorial waters, and every fishing boats have to get registration licence for swordfish fishing (Anon. 2008). This fishery is carried out only about 6-7 months per year due to the meteorological conditions and phase of the moon. When not fishing for swordfish and during the closed season, many of swordfish fishermen are engaged to the other coastal fisheries and trawling, and tourism or farming.

Harpooning has been used for thousands of years as near shore subsistence activities in subtropical areas (Ward et al., 2000). In Turkey, Artüz (1963) firstly reported that the harpoon fishing was carried out between May and June during the calm and sunny days in the Sea of Marmara. However, since the disappeared of swordfish in the Sea of Marmara, this fishery has been gone towards to the Gökçeada Island, northern Aegean Sea for the last three decades. Despite being considered inefficient method, harpooning has still been used to catch swordfish in the certain area.

Longlining is a developing method in recent years, and all of longliners in Fethiye region have used a semi- mechanized system since 1998. Additionally, there are wide varieties of pelagic longlines for swordfish in Turkey (Erdem and Akyol, 2005; Akyol and Ceyhan, 2007). In Özdere, longlining for swordfish, started in 2003 is new activity for Kuşadası Bay and last year, it extended to Gümüldür port in the same bay. ICCAT (2008) reported that the swordfish longline fishing was the most important fisheries in the Mediterranean with this target, accounting more than 76% of the total Mediterranean catches of swordfish in 2006, whereas using of this gear is still lower percentage in Turkey.

More than 18 species were found as by-catch for both gillnetting and longlining. However, gillnet fishermen claimed that a few dolphins and sea turtles were tangled to the net incidentally, but they can be saved its life mostly. According to them, dolphin and sea turtle casualties are met by chance occasionally and they never seen to the whale and sea birds. Öztürk et al. (2001)’s study verified this state that the only 10 specimens of dolphins, S. coeruleoalba (7), T. truncates (2), G. griseus (1) in the Aegean Sea were reported from swordfish gillnet fishery during May and June 1999 and 2000. But increasing of it’s casualties is likely towards to Levantine.

The length distribution of swordfish was ranged from 51 to 242 cm and the average lengths according to fishing gears shown that the GN was the most size selective gear among the others. The about 65% of swordfish had a LJFL less than 80 cm and LL and PS were responsible from this phenomenon. Really, Ceyhan and Akyol (2009) reported that the gillnetting was caught the larger specimens (>130 cm) in the highest percentage (90%) than longline.

Length-weight relationship in all fish indicated positive allometric growth (b=3.34), and equation was W=0.0022LJFL3.34, R2=0.976. In general, there are positive allometric growth in swordfish according to b coefficients (b>3) in recent Turkish studies (Alıçlı, 1996; Alıçlı and Oray, 2001; Akyol et al. 2005; Erdem and Akyol, 2005; Alıçlı, 2008).

1474

In 2002 and 2003, EU and ICCAT enforced a recommendation prohibiting the use of drift-nets in the Mediterranean. Afterwards, drift-netting in Turkey was also banned in 2006 (Anon., 2006). But many of fishermen, used pelagic gillnet for swordfish has been shown the reaction againts to the drift-net prohibition. Afterwards, they were found the “Association of the Fishing for Swordfish and Albacore” in Poyrazköy, Istanbul in 2008, and more than 60 fishermen enrolled to this association. Moreover, they have been started the struggle for their rights since then. They have been applied to the supreme court. They claimed that the pelagic gillnet fishery, dates back to early of the 1900’s were traditional and it was uncomparable with the large scale Mediterranean drift-net fishery. Fishermen do not want abandon their nets unless getting any compansate from the fishery authority. The fishermen hope the using of their pelagic gillnets till transition process, which includes converting to longlining and financial supporting, will be completed. Finally, management of swordfish in Turkey should include the plan, covering appropriate fishing capacity, swordfish size limitations, observing programme etc., for sustainability.

Acknowledgements

This study is funded by TUBITAK project (108 O 210) and we also thank to chair and members of the Association of the Fishing for Swordfish and Albacore for their valuable help during the fish measurements and for given the opportunity to work freely onboard.

References

Akyol, O., Erdem, M., Ünal, V. and Ceyhan, T 2005, Investigations on drift-net fishery for swordfish (Xiphias gladius L.) in the Aegean Sea. Turk J. Vet. Anim. Sci., 29:1225-1231. Akyol, O. and Ceyhan, T. 2007, Characteristics of Three Various Types Longline for Swordfish (Xiphias gladius L.) in Datça- Peninsula, Southern Aegean Sea. The ICES/FAO Meeting of Working Group on Fishing Technology and Fish Behaviour, 22-27 April, Dublin, Ireland. ICES CM 2007/FTC:06 Ref. ACFM, 191 p. Akyol, O., Karakulak, F.S., Ceyhan, T. and Dede, A. 2008, Driftnets, used in Turkish seas and the regulations. E.Ü. Su Ürünleri Dergisi, 25(2):153-157. (in Turkish). Alıçlı, Z. 1996, Investigations on length-weight relationships of swordfish (Xiphias gladius L.,1758) in South- eastern Mediterranean. İst. Üniv. Fen Bil. Enst., Ph.D. Thesis, 112 p. (in Turkish). Alıçlı, T.Z. and Oray, I.K. 1995, A preliminary report on the investigation of swordfish (Xiphias gladius L.1758) caught in the Turkish waters. Collect. Vol. Sci. Pap. ICCAT, 44(1): 148-150. Alıçlı, T.Z. and Oray, I.K. 1996, Second report on the investigation of swordfish (Xiphias gladius L.,1758) caught in the Turkish waters. Collect. Vol. Sci. Pap. ICCAT, 45(1): 141-143. Alıçlı, T.Z. and Oray, I.K. 2001, Age and growth of swordfish (Xiphias gladius L.,1758) in the eastern . Collect. Vol. Sci. Pap. ICCAT, 52(2): 698-707. Alıçlı, T.Z. 2008, Biometric relationships and condition factor of swordfish, Xiphias gladius L., 1758. İstanbul Universitesi Su Ürünleri Dergisi, 23:29-39. Anon. 2006, Turkish Fishery Regulation Circular (37/1) for Marine and Inland Commercial Fisheries in Fishing Season 2006-2008. T.C. TKB-KKGM, R.G. Sayı: 26269 Ankara, 108 p. (in Turkish). Anon. 2008, Turkish Fishery Regulation Bulletin (2/1) for Marine and Inland Commercial Fisheries in Fishing Season 2008-2012. T.C. TKB-KKGM, R.G. Sayı: 26974, No: 2008/48, Ankara, 112 p. (in Turkish). Artüz, M.I. 1963, Contribution to the knowledge of the biology of the swordfish (Xiphias gladius L.) in the Sea of Marmara. Proc. Gen. Coun. Medit., 7: 459-471. Ceyhan, T. and Akyol, O. 2009, Swordfish (Xiphias gladius L.) fishery in Turkish Aegean Sea. Collect. Vol. Sci. Pap. ICCAT, 64(6): 2069-2078. Demir, M., Acara, A. and Arımk, N. 1956, Investigations on swordfish (Xiphias gladius L.). Hidrobiologi Mecmuası, Ist. Univ. Fen Fak. Hidr. Araş. Enst. Yayınları Seri A, 3:137-143. (in Turkish). Deveciyan, K. 1915, Fish and Fishery in Turkey. Çeviri: Erol Üyepazarcı, 2006, Aras Yayıncılık, İstanbul, 574 p. (in Turkish). Erdem, M. and Akyol, O. 2005, A preliminary study on longlining of swordfish (Xiphias gladius L., 1758) in Fethiye Region (Mediterranean). E.Ü. Su Ürünleri Dergisi, 22: 201-204. (in Turkish).

1475

FAO. 2000, Fishstat Plus: Universal Software for Fishery Statistical Time Series. Ver. 2.3. FAO Fish. Dept., Data and Statistics Unit, Rome. Gökoğlu, M. and Oray, I.K. 1992, An Investigation on lonlining of swordfish and characteristics of longlining boats and their operations in Antalya Bay. Su Ürünleri Avlama ve İşleme Tek. Seminer Tebliğleri, İst. Beyoğlu Rotary Kulübü yayınları No:14, 48-51 pp. (in Turkish). ICCAT 2008, Statistical Bulletin (1950-2006). Vol. 37, July 2008, pp. 194. Kahraman, S.A., Dağlı, Y. 2008, Evliya Çelebi’s Travel Notes with Current Turkish: Istanbul, (in Turkish). 1.Cilt, 2. Kitap, Yapı Kredi Yayınları 1808, Istanbul, 765 p. Onat, S. 1970, Pelagic fishes and their catching periods. Balık ve Balıkçılık Dergisi, EBK Yayınları, İstanbul, 18(3): 39-40. (in Turkish). Öztürk, B., A.A. Öztürk and A. Dede. 2001, Dolphin by-catch in the swordfish driftnet fishery in the Aegean Sea. Rapp.Comm. Int. Medit., 36, pp.308. Tokaç, A., Metin, C., Lök, A. and Gurbet, R. 1991, Swordfish (Xiphias gladius L.,1758) fishery by using drift nets in northern Aegean Sea. Eğitiminin 10. Yılında Su Ürünleri Sempozyumu, 12-14 Kasım, İzmir, 653- 661 s. (in Turkish). Ward, P., Porter, J.M. and Elscot, S. 2000, Broadbill swordfish: Status of established fisheries and lessons for developing fisheries. Fish and Fisheries, 1: 317-336.

Table 1. Swordfish fleet’s characteristics.

Mean ±SE n (min.-max.) Σ Boat length (m) 100 12,4 ±0,55 1243 (6,2–36,0) Tonnage (GT) 82 20,2 ±3,07 1653 (1,8–130) Machine Power (hp) 100 162,4 ±13,69 16244 (9–680) Boat age (year) 96 18 ±0,76 636 (2–34) Fuel Consumption (l.day-1) 100 89,9 ±8,20 8986 (6–400) Personnel 100 3,6 ±0,17 356 (1–10) GT, Gross tonnage; hp, Horse power; SE, Standard error.

Table 2. Summary statistics on the length of samples according to fishing gears.

Summary Fishing gear statistics GN LL PS Mean 140.8 85.9 81.3 Standard Error 2.8 1.3 0.7 Median 98.0 75.0 77.0 Minimum 68.0 60.0 51.0 Maximum 242.0 172.0 185.0 n 286 280 636

1476

Table 3. History of swordfish fishery in Turkey.

Fishing Period Starting area Present status Season Source gears TP 1630s - 1970 Bosphorus Abandoned April - February Evliya Çelebi’s Travel Notes1, O. Torlak2 and Deveciyan (1915) HP 1950s - 1970s Bosphorus and Only off Gökçeda Formerly and Artüz (1963), N. Taşcı3, Sea of Marmara Nowadays, May- T. Torlak4 and Onat June (1970) LL 1960 - 1975 Sea of Marmara Since 1974, Fethiye Formerly, Autumn R. Ertaş5, O. Somyürek6 Since 2003, Özdere months and H.H. Can7 Nowadays, Dec.- May GN 1900s - 1960s Bosphorus Musellim Strait, Formerly, June- Deveciyan (1915), Doğanbey Bay and October N. Taşçı and Onat (1970) off Fethiye in the Nowadays, April - Aegean Sea September PS 1960s - 1970s Bosphorus and Whole of Aegean Sea Formerly, Autumn N. Taşcı Sea of Marmara months Nowadays, Sept. - April 1Kahraman and Dağlı (2008); 2Torlak, O., Pers. comm. Jan. 13, 2009 Poyrazköy (İstanbul); 3Taşcı, N., Pers. comm. July 05, 2009 Poyrazköy (Istanbul); 4Torlak, T., Pers. comm. Aug. 27, 2009 Poyrazköy (Istanbul); 5Ertaş, R., Pers. comm. Oct. 26, 2009 Marmara Island (Balıkesir); 6Somyürek, O., Pers. comm. Oct. 27, 2008 Fethiye (Muğla); 7Can, H.H., Pers. comm. Sept. 24, 2008 Özdere (Izmir).

Figure 1. Distribution of fishing ports and fishing areas according to operation types in Turkish waters (numbered circles indicate the total number of swordfish boats).

1477

1% 12% Fishing Gears

24% GNalb. GNswo. LL HP

30% GN+LL GNalb+swo

21%

12%

Figure 2. Proportion of fishing gears in sum of swordfish boats.

Figure 3. A modified gillnet, sampled from Poyrazköy, Istanbul.

1478

100 )

80

60 GN 40 LL PS 20 Cumulative frequency (% 0

0 50 70 90 1 30 70 10 30 1 1 150 1 190 2 2 LJFL (cm)

Figure 4. Percentage cumulative length frequency distribution of swordfish according to fishing gears.

180000 160000 W = 0,0022LJFL3,3446 140000 R2 = 0,976 n=1203 120000 100000 80000

Weight (g) 60000 40000 20000 0 50 75 100 125 150 175 200 225 250 LJFL (cm)

Figure 5. Length-weight relationship of swordfish in Turkish seas.

1479