SCRS/2002/040 Col. Vol. Sci. Pap. ICCAT, 55(1): 131-137 (2003) DESCRIPTION OF THE JAPANESE LONGLINE FISHERY AND ITS FISHERY STATISTICS IN THE MEDITERRANEAN SEA DURING THE RECENT YEARS N. Miyabe 1 SUMMARY The Japanese fishery in the Mediterranean Sea entirely targets on bluefin tuna with the use of longline gear. In this fishery, a small amount of swordfish is caught incidentally. Recently, Japanese bluefin catch in the Mediterranean Sea has been decreasing from about 800 MT in 1995 to about 400 MT in 1999, though the fishing effort has been maintained approximately at the same level. Large adult fish migrating for spawning are predominant in the catch. Research activities by Japan in the Mediterranean Sea include archival tagging for juveniles using farmed bluefin tuna in Croatia. RÉSUMÉ La pêcherie japonaise en Méditerranée cible exclusivement le thon rouge au moyen de la palangre. Dans cette pêcherie, une faible quantité d espadon est capturée accidentellement. Ces dernières années, les captures japonaises de thon rouge en Méditerranée ont diminué, passant de 800 t en 1995 à environ 400 t en 1999, bien que l effort de pêche ait été maintenu approximativement au même niveau. Les gros poissons adultes qui migrent pour se reproduire prédominent dans les captures. Les activités de recherche menées par le Japon en Méditerranée consistent notamment à marquer des juvéniles au moyen de marques-archives en utilisant le thon rouge élevé en Croatie. RESUMEN La pesquería japonesa en el Mediterráneo se centra sólo en el atún rojo capturado con palangre. En dicha pesquería, se capturan pequeñas cantidades de atún rojo de forma incidental. Recientemente, la captura de Japón de atún rojo en el mar Mediterráneo ha experimentado un descenso, pasando de aproximadamente 800 t en 1995 a 400 t en 1999, aunque el esfuerzo pesquero se ha mantenido aproximadamente en el mismo nivel. Los grandes adultos que migran para desovar predominan en las capturas. Las actividades de investigación desarrolladas por Japón en el Mediterráneo incluyen el marcado con marcas archivo de los juveniles utilizados en la cría de atún rojo en Croacia. KEY WORDS Fishing grounds, Long lining, Fishery statistics, Tuna fisheries, Pelagic fisheries, Size composition, Bluefin tuna, Swordfish, Mediterranean Sea. 1. TREND OF CATCH, EFFORT AND SIZE OF FISH FOR BLUEFIN TUNA Japanese longline fishing for bluefin in the Mediterranean Sea started in 1972 and the catch peaked in 1974 at 2195 MT. Table 1 and Figure 1 show historical data on fishing effort and catch by species. During the recent years, fishing season starts in March at the mouth of the Gibraltar Strait (Figure 2 1 NRIFSF. 5-7-1, Orido, Shimizu, Shizuoka, 424-8633. Japan. Miyabe@fra.affrc.go.jp. 131
and Figure 3). Apparently, the fishing boats target spawners that seem to migrate into the Mediterranean Sea for spawning. In the late April some boats entered into the Mediterranean and fish around the Balearic Islands, Sicily and off Libya. The Japanese boats have refrained from fishing during the spawning season. From 1975, the Fisheries Agency of Japan (FAJ), as a voluntary measure, prohibited Japanese longline vessels from operating in the Mediterranean Sea from May 21 to June 30 by Ministerial order. Then, in 1994, the FAJ amended this order to alter the closed season, from June 1 to July 31 in accordance with the 1993 ICCAT Recommendation. The motivation for this limit comes from the fact that this is better utilization of the stock as the price of the fish in a spawning condition is much less than the pre-spawning fish, which usually gets the highest price, while the fishing effort is limited to some extent. During the rest of months, there has been no significant fishing in this area except some in July. The limited size data indicate that most of the bluefin catch are composed of large fish larger than 200 cm in fork length (Figure 4). The same data for swordfish indicate that the size caught ranges from 90 to 230 cm in eye-fork length but majority is 120 to 200 cm (Figure 4). 2. BLUEFIN TUNA FARMING Bluefin tuna farming, in which several Japanese companies are often involved, has been developing rapidly and spreading to various Mediterranean countries. No farmed bluefin were imported to Japan from the Mediterranean Sea before 1997. The amount of import increased from 670 MT (whole weight) in 1997 to about 5200 MT in 2000, 6950 MT in 2001, according to ICCAT Bluefin Tuna Statistical Document (BTSD) provided by the Fisheries Agency of Japan (Miyake et al., 2002). More detail on the production and activities of bluefin tuna farming in the Mediterranean Sea is provided by the same data source. 3. RESEARCH Research activities for bluefin tuna in the Mediterranean Sea have been conducted under the ICCAT Bluefin Year Program (BYP), in collaboration with GFCM. The BYP covers general biological surveys, improvement of statistics and stock assessment. Japan continues to participate in the BYP. The Bluefin Statistical Document Program (BTSD) provides valuable information for improvement of basic catch statistics and for identifying possible under reporting of the bluefin catches. Japan conducted archival tagging for Mediterranean bluefin tuna in 1999 and 2000. The original plan for releasing adult bluefin from the eastern Atlantic including the Mediterranean has to be modified for juveniles to be tagged, due mainly to the high cost to buy sample fish for release. The plan was further changed from wild to farmed bluefin, again due to the high cost to charter boats for catching them. Finally, a Croatian farming company kindly offered to carry out archival tagging on their fish kept in cages for about four months. A total of 76 juveniles were released in the two years mentioned above and 17 fishes were recovered as of the end of March 2002. The brief result of this experiment (Yamashita and Miyabe 2001) was presented to the Joint GFCM/ICCAT meeting held in Malta in 2000. All the fish recovered, 1 to 15 months at liberty, seem to have remained around the Adriatic Sea. Japan, jointly with other longline countries in the Indian Ocean under the framework of the Indian Ocean Tuna Commission, started a survey, from 2000 globally, on predation of tunas and tuna-like-fishes by marine mammals (mostly false killer whale) and sharks. This survey was motivated by serious the predation problem in the tuna longline catches by small cetaceans as well as by sharks in the Indian Ocean. As much as 30 % of the longline catches could be eaten by marine mammals, to a lesser degree by sharks before the catches are retrieved on board. This project forms a part of multi-species or ecosystem approaches for sustainable use of marine organisms, especially the sustainable utilization and control of whale stocks, which have become more and more important subject for study. As of 2001, there has been no report of predations from Japanese longline boats operating in the Mediterranean Sea. 132
With respect to bluefin farming, environmental pollution around the farms and safety as food of farmed bluefin tuna such as dioxin contents in farmed tunas should be carefully monitored in order to meet the recent requirements on increased transparency of cultured fish from the view point of public domain including consumer. In this respect, according to the FAO Code of Conduct for Responsible Fisheries and responding to public awareness and growing interest in safe foods, Japan established a domestic law for the purpose of sustainability in aquaculture that prevents epidemic diseases and any adverse effects on environment that might be caused by aquaculture. 4. MONITORING AND REGULATORY MEASURES For monitoring the fishing activities of Japanese longline boats as well as large foreign longline boats in the Mediterranean Sea, the Japanese Fisheries Agency routinely sends the patrol boats there and presents the sighting information on FOC/IUU boats to the ICCAT. Japan is prepared for present the sighting information on request. It should be stressed that publicity aimed at ordinary people regarding the problems of the FOC/IUU activities is very important to make consumers aware of how these activities affect the sustainable use of the fisheries resources. See more information regarding FOC/IUU problems (http://www.jfa.maff.go.jp/fochp/main/index.htm). Currently, longline fishing by large boats over 24m LOA is prohibited in the Mediterranean Sea during June and July by the ICCAT regulation. REFERENCES MIYAKE, P. M. et al. 2002. General review of bluefin tuna farming in the Mediterranean area. SCRS/02/36. Presented to the 6th GFCM/ICCAT Joint Meeting, Malta, May 2002. YAMASHITA, H. and N. Miyabe. 2001. Report of bluefin tuna archival tagging conducted by Japan in 1999 in the Adriatic Sea. ICCAT, Col. Vol. Sci. Pap. 52:809-823. 133
Table 1. Japanese Catch (MT) of bluefin tuna and swordfish in the Mediterranean Sea. Year Sets Hooks in thousand BFT SWO 1972 84 122 112 1973 95 145 246 1974 816 1413 2195 1975 785 1470 1260 1976 722 1493 968 1 1977 208 447 520 0 1978 53 111 61 2 1979 108 207 99 3 1980 116 262 119 1 1981 57 122 100 0 1982 365 868 961 5 1983 437 1021 677 6 1984 815 1945 1036 19 1985 826 2069 1006 14 1986 436 1128 341 7 1987 308 811 280 3 1988 320 844 258 4 1989 172 448 127 1 1990 116 323 172 2 1991 104 287 85 1 1992 188 505 123 2 1993 448 1260 793 4 1994 638 1736 536 2 1995 471 1216 813 4 1996 1009 2725 765 5 1997 427 1167 185 5 1998 453 1242 361 7 1999 506 1463 381 5 2000 363 1072 136 1 C atch (M T ) 3000 2500 2000 1500 1000 500 Effort and Catch 0 1972 1976 1980 1984 1988 1992 1996 2000 Year Fig. 1. Trend of fishing effort (in number of hooks) and catch by species for the Japanese longline fishery in the Mediterranean Sea (east of 5 W). 134 BFT SW O H ooks 3000 2500 2000 1500 1000 500 H ooks (in 1000)
Fig. 2. Annual distribution of fishing effort in number of hooks in the Mediterranean Sea and adjacent waters during 1997-2000. 135
Fig. 3. Average monthly distribution of fishing effort by the Japanese longline fishery in the Mediterranean Sea and adjacent waters during March to June in 1997-2000. 136
14 12 B FT Length Frequency 1996 1998 N um ber of F ish 10 8 6 4 2 0 100 120 140 160 180 200 220 240 260 280 300 Fork Length (cm ) N um ber of F ish 10 8 6 4 2 S W O Length Frequency 1984 1985 0 60 80 100 120 140 160 180 200 220 Eye-Fork Length (cm ) Fig. 4. Sample length frequencies of bluefin tuna and swordfish in the Mediterranean Sea caught by the Japanese longline fishery. 137