BLUEFIN TUNA CAUGHT BY SENEGALESE BAITBOAT AND LANDED IN DAKAR IN 2013

Transcription

1 SCRS/204/58 Collect. Vol. Sci. Pap. ICCAT, 7(3): (205) BLUEFIN TUNA CAUGHT BY SENEGALESE BAITBOAT AND LANDED IN DAKAR IN 203 Fambaye Ngom Sow and Sidi Ndaw 2 SUMMARY This study presents a summary of the data and information available regarding bluefin tuna catches and landings in the port of Dakar by the Senegalese baitboat fishery in December 203. The data are presented by gear, geographical area, fishing day, landing day, mean length, mean weight and size composition of the fish landed. RÉSUMÉ Le présent document résume les quelques données disponibles et des informations sur du thon rouge capturé et débarqué par un canneur sénégalais à Dakar en décembre 203. Les données présentées portent sur la taille moyenne, le poids moyen, la composition par tailles des poissons débarqués et le type d'échantillons tissulaires prélevés. RESUMEN Este documento resume la información y los datos disponibles acerca del atún rojo capturado y desembarcado por un cañero senegalés en Dakar en diciembre de 203. Los datos que se presentan son talla media, peso medio y composición por tallas de los peces desembarcados, así como el tipo de muestras de tejido recopiladas. KEYWORDS Bluefin tuna, Catches, Baitboat, Dakar Introduction In East Atlantic, the southern theorical ecologic limit of bluefin tuna is the Cap Blanc (2 N). Bluefin tuna catches are always very uncommon in the south of the Canary Islands. The tuna baitboat fishing operating in Senegal coastal area between 2 to 2 N (West Africa) target primarily three species of tropical tunas yellowfin, Skipjack and Bigeye. In December 203, 5800 kg of bluefin tuna were landed by one Senegalese baitboat based in Dakar. These catches were sold on local market. It is in this context that this note is produced in order to give the relative information to these catches carried out by one Senegalese baitboat based in Dakar. The data are the total landings and the size composition. Methodology adopted Following the information collected, the Centre de Recherches Océanographiques de Dakar/Thiaroye (CRODT) and the Direction des Pêches Maritimes of Senegal conducted jointly the investigations in order to compile documents and information relative on bluefin catches in 203. Thus, many sources were collected. This paper is based upon: Documents from the customs office. Chercheur au Centre de Recherches Océanographiques de Dakar/Thiaroye; famngom@yahoo.com 2 Responsable du Bureau des statistiques de la Direction des pêches Maritimes, sidindaw@hotmail.com 499

2 Sampling in port done by the technicians from the Centre de Recherches Océanographiques de Dakar- Thiaroye (CRODT). Biological samples were collected, white skeletal muscle near caudal fin and fin clip were sampled on each individual fish. The sampling protocols for the GBYP biological sampling was used. (Appendices and 2). All samples were sent to Azti. All the fishery data corresponding were selected to be analyzed. For calculation we used the equation relationship between L- W; W= *FL (Anon. 984) Results and discussion In total, 23 specimens were unloaded in Dakar port during the fourth quarter of 203. The total catches were kg. Bluefin tuna were fished in Mauritania area around the latitude 8 and longitude 7. They were mixed with the school of tropical tunas. The mean size is around 245 cm and the mean weight 252 kg. These measurements indicate that the captured individuals were adults. The sizes varied between 223 and 272 cm (Table ). The Figure indicates the fishing areas of the baitboat fleet based in Dakar in 203 (2-2 N) and the bluefin tuna catches area. The Figure 2 shows the size distribution in weight and number of bluefin caught by this boat. Conclusion The presence of bluefin in this southern area could be linked to trophic migration of bait and environmental changes. More attention should be devoted in Mauritanian area. As a reminder, in 200 there were accidental catch of bluefin tuna by Spanish baitboat based in Dakar in the same area (Ngom and Ndaw, 20). References Anon. 984, Report of the Bluefin Tuna Workshop, Japan September 983. Collect. Vol. Sci. Pap, ICCAT, 9: Bard, F.X., Bach, P. and Josse, E. 998, Habitat et écophysiologie des thons : Quoi de neuf depuis 5 ans? Collect. Vol. Sci. Pap, ICCAT, 50(): Ngom F. and Ndaw S. 20. Bluefin tuna caught by Spanish baitboat and landed in Dakar in 200. Collect. Vol. Sci. Pap, ICCAT, 66(2):

3 Table. Size, number and weight off individual bluefin tuna. Sizee (cm) Total Taille moyenne Poids moyen (Kg) Number 23 Weight (Kg) Figure. Fishing areas and catch distribution of the baitboatt fleet based in Dakar 203 and the BFT catches area. 50

4 Figure 2. Size frequencies distribution in weight and number. 502

5 Appendix Sampling information INDIVIDUAL FISH CODE CODE AREA PARTNER FISHING GEAR ID INDIVIDUAL NUMBER SIZE CLASS CODE CRODT Centre de Recherches Oceanographiques de Dakar / Thiaroye MS Mauritanian Sea BB Baitboat L= Large M = Muscle F = Fin TISSUE COLLECTED TISSUE TISSUE CODE CODE 2 CRODT MS BB L M F CRODT MS BB 2 L M F CRODT MS BB 3 L M F CRODT MS BB 4 L M F CRODT MS BB 5 L M F CRODT MS BB 6 L M F CRODT MS BB 7 L M F CRODT MS BB 8 L M F CRODT MS BB 9 L M F CRODT MS BB 0 L M F CRODT MS BB L M F CRODT MS BB 2 L M F CRODT MS BB 3 L M F CRODT MS BB 4 L M F CRODT MS BB 5 L M F CRODT MS BB 6 L M F CRODT MS BB 7 L M F CRODT MS BB 8 L M F CRODT MS BB 9 L M F CRODT MS BB 20 L M F CRODT MS BB 2 L M F CRODT MS BB 22 L M F CRODT MS BB 23 L M F 503

6 Appendix 2 Sampling data Catch Date Sampling Date Latitude Longitude Length [cm] Length Type Weight (Kg) Notes 8/2/203 03/04/ N 700W 264 FL 309 Fin clip & white skeletal muscle 8/2/203 03/04/ N 700W 255 FL 280 Fin clip & white skeletal muscle 8/2/203 03/04/ N 700W 250 FL 264 Fin clip & white skeletal muscle 8/2/203 03/04/ N 704W 233 FL 25 Fin clip & white skeletal muscle 8/2/203 03/04/ N 704W 277 FL 355 Fin clip & white skeletal muscle 8/2/203 03/04/ N 704W 249 FL 26 Fin clip & white skeletal muscle 8/2/203 03/04/ N 655W 269 FL 326 Fin clip & white skeletal muscle 8/2/203 03/04/ N 655W 233 FL 25 Fin clip & white skeletal muscle 8/2/203 03/04/ N 655W 23 FL 66 Fin clip & white skeletal muscle 8/2/203 03/04/ N 655W 234 FL 28 Fin clip & white skeletal muscle 8/2/203 03/04/204 89N 754W 254 FL 276 Fin clip & white skeletal muscle 8/2/203 03/04/204 89N 754W 267 FL 39 Fin clip & white skeletal muscle 8/2/203 03/04/204 89N 754W 255 FL 280 Fin clip & white skeletal muscle 8/2/203 03/04/204 89N 754W 246 FL 252 Fin clip & white skeletal muscle 8/2/203 03/04/204 88N 759W 254 FL 276 Fin clip & white skeletal muscle 8/2/203 03/04/204 88N 759W 24 FL 237 Fin clip & white skeletal muscle 8/2/203 03/04/204 88N 759W 238 FL 229 Fin clip & white skeletal muscle 8/2/203 03/04/ N 74W 247 FL 255 Fin clip & white skeletal muscle 8/2/203 03/04/ N 74W 250 FL 264 Fin clip & white skeletal muscle 8/2/203 03/04/ N 74W 276 FL 352 Fin clip & white skeletal muscle 8/2/203 03/04/ N 720W 227 FL 99 Fin clip & white skeletal muscle 8/2/203 03/04/ N 720W 23 FL 20 Fin clip & white skeletal muscle 8/2/203 03/04/ N 720W 255 FL 280 Fin clip & white skeletal muscle 504