REPORT ON THE TURKISH BONITO (Sarda sarda) FISHERY IN 2000/2001

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1 SCRS/23/123 Col. Vol. Sci. Pap. ICCAT, 56(2): (24) REPORT ON THE TURKISH BONITO (Sarda sarda) FISHERY IN 2/21 Isik K. Oray 1,2, F. Saadet Karakulak 2, Mustafa Zengin 3 SUMMARY A bonito fishery, which is very important for Turkey, is carried out during the migration of the bonitos from the Black Sea to the Mediterranean Sea. In this study, the bonito fishery in Turkish waters, catch at size and the length-weight relationship are explained. RÉSUMÉ La pêche à la bonite à dos rayé, qui revêt une grande importance pour la Turquie, s effectue au cours de la migration des bonites à dos rayé de la Mer Noire vers la Mer Méditerranée. Le présent document décrit la pêcherie de la bonite à dos rayé dans les eaux turques, la prise par taille et le rapport longueur-poids. RESUMEN Durante la migración de los bonitos desde el Mar Negro al Mar Mediterráneo se desarrolla una pesquería de bonito muy importante para Turquía. En este estudio se explica la pesquería de bonito en aguas turcas, la captura por clases de talla y la relación talla-peso. KEY WORDS Bonito, size composition, length-weight relationship, Turkey 1 European University of Lefke; isikoray@yahoo.com 2 University of Istanbul, Faculty of Fisheries Ordu cad. No: 2, 3447 Laleli, Istanbul, Turkey; karakul@istanbul.edu.tr 3 Central Fisheries Research Institute, 61 Trabzon, Turkey ; mzengin@hotmail.com 784

2 1 Introduction Bonitos are important for the Turkish fishery. The purse seiners and the artisanal fishermen fish bonitos in Turkish waters. Bonitos in the Mediterranean and in the Aegean Sea pass to the Sea of Marmara and to the Black Sea for spawning in the spring. They migrate back to the Sea of Marmara and to the Mediterranean Sea in autumn (Devedjian, 1926; Slastenenko, ; Nümann,1955). The bonito fishery is conducted after spawning during the intensive migrations (Oray and Karakulak, 1997). The history of the bonito fishery is very old. The fishery which was carried out by dalians (traps), lines, trammel nets, and cast nets previously, is conducted by purse seines since the 195s. 2 Materials and Methods In 2-21, 1168 bonitos caught in the Black Sea and in the Sea of Marmara were sampled. The length of the fish were measured as and their weight determined as TW (g). 3 Results 3.1. Description of Fisheries Bonitos are fished by dalian (traps), purse seiners, trammel nets, drift nets, beach seines and hand lines. Fishing starts in September and ends in December. In some months the fishery goes on till January. Bonitos are fished in the Black Sea, in the Sea of Marmara, and in the Northern Aegean sea. Purse seiners stationed in the Black Sea and in the Sea of Marmara fish bonitos. As these purse seiners carry two different mesh sized nets during the bonitos season; anchovy, bluefish, horse mackerel are also fished. According to the years, the catch figures show fluctuations (Figure 1). The catch in 1983 which was 2934 tons declined to 4667 tons in In 1998 the catch figure for bonitos increased to 24 tons (DIE, ) Size Composition The length frequency of the measured bonitos is shown in Figure 2 and 3. The length frequency of the individuals for the year of 2 (Table 1) was between cm; the mean size being 32.6±.17 cm for 21 (Table 2); the lengths varied between cm, the mean length being 29.8 ±.59 cm. In 21 the mean length of the caught fish was less. In this study, most of the caught bonitos were found to be in the size interval of 3-34 cm, which comprised 47.6 % of the measured fish, followed by the cm size interval with % and the cm size interval with %. The ratio of the individuals between cm was 9.75 %. Looking at the length and weight parameters of bonitos caught in 2 an increase in the size is clearly seen. Due to the low sample numbers in 21, this increase in the size cannot be seen clearly Length-weight relationship Regression analyses of bonito body weight as a function of length for both sexes are shown in Fig 4. The regression of weight on length was highly significant (r 2 =.925). The fork length ranged between 21.8 cm and 7.5 cm and body weight from 11 g to 5 g. 785

3 The mathematical relationship between the bonito length and weight can be described by following equation: W =.39 FL Conclusion Due to the reproduction period of the pelamides, the catch of bonitos in Turkish waters is restricted between 1 April- 1 September. The minimum size is determined as 25 cm. Bonitos in the Turkish waters reach in the first year 41 cm, in the second year cm and in the 3 rd year cm (Nümann, 1954). In our study, the ratio of the bonitos over 25 cm is 91,81 %; the ratio of the fish smaller than the minimum size 8,19 %. Even though catches comply with the catch restrictions, the fluctuations in the catches probably indicate the unstability in the stock. The caught bonitos are with 9.75 % in the size interval of cm. These fish are probably in the age group and 1. Probably due to the fishing pressure on these immature fish, the stock cannot renew itself. Investigations on the biology of these fish in Turkish waters are not numerous. Studies on the maturity has to be determined. The minimum size as well other studies on the biology of bonitos have to conducted. References DEVEDJIAN, K., Pêche et Pêcheries en Turquie. Imprimerie de l Administration de la Dette Publique Ottomane, Istanbul, 48 pp. DIE (198-21). Fisheries Statistics. State Institution of the Statistics Prime Ministry Republic of Turkey, p.3, Ankara, Turkey. (in Turkish) MINISTRY OF AGRICULTURE AND RURAL AFFAIRS, Turkey Denizlerde ve Içsularda Ticari Amaçli Su Ürünleri Avciligini Düzenleyen Av Dönemine ait Sirküler. Ankara, 84 pp. (In Turkish). NUMANN, W Croissance et Migrations des Pelamides (Sarda sarda) dans Les Eaux de La Turquie. FAO, Document Technique No.42, 54/9/5326, Rome -Italy. NUMANN, W Die Pelamiden des Schwarzen Meeres, des Bosporus, des Marmara und der Dardanellen (Sarda sarda). Istanbul Üniversitesi Fen Fakültesi, Hidrobiyoloji Arastirma Enstitüsü Yayinlarindan. Cilt III, Sayi 2-3, pp , Istanbul. ORAY, I.K., Ozberk, G., Karakulak, F.S Investigations on the purse-seine fishing of bonitos, Sarda sarda (Bloch,1793), in turkish waters in ICCAT, Coll. Vol. Sci. Pap., Vol. XLIV (4): pp , Madrid. SLASTENENKO, E Karadeniz Havzasi Baliklari. Et ve Balik Kurumu Umum Müdürlügü Yayinlarindan, s , Istanbul. 786

4 Table 1. The mean length and weight according to the months in 2. 2 September October November December Mean FL 31.5± ±.2 33.± ±.1 Max FL Mean TW ± ± ± ±1.9 Max.TW Table 2. The mean length and weight according to the months in 21. Mean FL Max. FL Mean TW Max.TW 21 Jan. Febr. September October November December ± ± ± ± ± ± ± ± ± ± ± ± Catch (MT) Year Figure 1. Catch of Bonitos (MT/year). 787

5 % Frequency N = Figure 2. The fork length composition of bonitos caught by purse seiners in 2. % Frequency N = Figure 3. The fork length composition of bonitos caught by purse seiners in TW (g) y =,39x 3, Figure 4. Length weight relationship of bonito in Turkish waters. 788