National Research Institute of Far Seas Fisheries
5–7–1 Orido, Shimizu, Shizuoka 424, Japan
The utilisation of elasmobranchs has a long history in Japan. For example, shark fin trade to China begun more than 200 years ago. Japan harvests more than 20 000t of elasmobranchs annually1. Bonfil (1994) classified Japan as a major elasmobranch fishing country in the world. Although world elasmobranchs harvests continue to increase, Japanese landings of elasmobranchs, including both sharks and batoids, are gradually decreasing and have been between 20 000 and 40 000t during the last decade (Figure 1). The economic importance of elasmobranchs to the Japanese fisheries products is relatively small. Japanese landing of elasmobranchs in 1995 was 22 271t and 0.3% of total marine product of Japan (MAFF 1997a).
The fisheries that catch sharks are classified into three groups in terms of the method of capture: (1) tuna longline fisheries, (2) trawl fisheries, and (3) other fisheries. The third group includes the high seas drift gillnet fishery, other gillnet fishery, bottom longline, and set net fisheries. The major sources of batoids landings are: (1) the trawl fishery operating in the East China Sea, (2) other trawl fisheries operating around northern part of Japan, and (3) other fisheries.
2. THE RESOURCE
2.1 Species composition of fishery
The major elasmobranchs species groups caught by Japanese fisheries are classifies into three groups of elasmobranchs; pelagics, benthic and coastal. Tuna longline and high seas driftnet fisheries mainly catch pelagic species. Blue shark is the dominant species among pelagic fisheries and comprises more than 70% in the tuna longline fishery. Taniuchi (1990) reported twenty-five species, which were caught by the Japanese tuna longline fishery, however his report was based on research conducted in the late 60s, and early 70s. In that period, Japanese tuna longline fisheries operated inside of EEZs of nations in the tropical Pacific Ocean. Also, Japanese tuna longline fishery also changed their target species from yellowfin tuna in the tropical waters to bigeye tuna in the temperate waters from the late 70s (Suzuki et al. 1977). Therefore the species composition of Japanese tuna longline fisheries changed and coastal species became very rare in the bycatch of this fishery (see Table 1, for old and new tuna longline research).
Pelagic species of sharks caught as bycatch in the northern pacific areas are shown as Table 1. The proportions of each species of pelagic sharks caught by salmon gillnet, flying squid driftnet, large mesh driftnet, and tuna longline fisheries are reported by Nakano (1996). Blue shark (Prionace glauca), salmon shark (Lamna ditropis) and spiny dogfish (Squalus acanthias) are major components of shark bycatch for salmon gillnet fisheries and consisting of 63.1%, 18.3% and 16.8%, respectively. Blue shark and salmon shark were two major bycatch species for flying squid driftnet fishery. These species comprise 93.0% and 5.8% of total shark bycatch of the fishery. Blue shark, shortfin mako shark Isurus oxyrinchus, cookie cutter shark Isistius brasiliensis, and salmon shark are mainly caught by large mesh driftnet fisheries as bycatch. The proportions taken of each species to total shark bycatch are 84.2%, 6.5%, 3.3% and 1.5% in respectively. The major pelagic shark species caught by the tuna longline fishery are blue shark, bigeye thresher shark (Alopias superciliosus), oceanic whitetip shark (Carcharhinus longimanus), silky shark (Carcharhinus falciformis), and shortfin mako shark and crocodile shark (Pseudocarcharias kamoharai). The proportion of pelagic sharks caught by the tuna longline fishery are 41.9%, 1.8%, 29.4%, 19.4%, 3.8%, and 0.2% in respectively in research during 1967–1970 and 75.3%, 14.7%, 3.9%, 1.7%, 1.3% and 1.2%, in respectively in research during 1992–1994. Almost all species caught by coastal longliners are utilised, but sharks caught by offshore and distant water longliners only use some species, and especially short-fin mako shark and all fins.
1 The major source of information used in this report comes from fishery statistics collected by the Statistics and Information Department of Ministry of Agriculture, Forestry and Fisheries (MAFF) of Japan. These statistics are published and widely distributed as bulletins entitled Annual Statistics of Fishery and Aquaculture Production and Annual Statistics of Fishery Products Marketing.
World elasmobranch catch (above) and Japanese elasmobranch catch (below)
|Kind of research/Species||Salmon driftnet||Squid driftnet||Large-mesh driftnet||Tuna longline 1992–1994||Tuna longline 1967–1970|
|Nb. of caught||Frequency (%)||Nb. of caught||Frequency (%)||Nb. of caught||Frequency (%)||Nb. of caught||Frequency (%)||Nb. of caught||Frequency (%)|
|Lamna ditropis||724||18.28||10 172||5.76||132||1.45||55||0.13|
|Prionace glauca||2 498||63.08||164 415||93.02||7 692||84.22||31 078||75.34||7 555||41.94|
|Carcharhinus longimanus||1 614||3.91||5 288||29.36|
|Carcharhinus falciformis||706||1.71||3 499||19.43|
|Alopias supercilosus||6 075||14.73||315||1.75|
|Total||3 960||176 746||9 133||41 250||18 012|
* Is caught, but data are not available.
Major elasmobranch species caught incidentally by trawl fisheries are stingrays (Dasyatis spp.) for the trawl fishery operating in the East China Sea and spiny dogfish and skates (Raja spp.) for the trawl fisheries operating in northern Japan. These species are landed and utilised into domestic markets. Coastal species including, Lamna ditropis, Spyrna spp., Mustelus spp., etc., are caught bymany coastal fisheries and are sometimes landed and utilised. Generally, it is difficult for the fishermen to utilise sharks, caught as non-target species and sometimes hard to sell due to lack of commercially sufficient amounts. In addition with major fisheries, there are some fisheries directly targeting sharks in Japan. For example coastal tuna longline fishery seasonally targets salmon shark offshore of Tohoku region. Some bottom longline fishery and driftnet fishery target spiny dogfish in the coastal waters.
2.2 Distribution of fishery
As mentioned above, the major methods of capture can be classified into three groups, i.e. tuna longline fisheries, trawl fisheries and other fisheries. Tuna longline fisheries include three groups, i.e. distant water, offshore and coastal tuna longline fisheries classified by size of vessels. The coastal tuna longline fishery operates in the area near Japan. The offshore tuna longline fishery operates in the northwestern Pacific Ocean, mainly from the equator to the waters near Japan and west of date line. The fishing grounds of the distant water tuna longline fleet include the Pacific, Atlantic and Indian Oceans.
The fishing grounds of the trawl fisheries consist of the southern and northern areas of Japan. The East China Sea is one of the major southern fishing grounds for the Japanese trawl fishery. The other fishing ground is along the coast of northern Japan including coastal waters of the Tohoku region and the waters around Hokkaido. The fishing effort exerted by these fisheries is declining owing to the reduction in the fleet size. High seas driftnet fisheries operated in the northern north Pacific and temperate waters of the South Pacific Ocean before the moratorium was set (Figure 2). The other coastal fisheries including bottom longline, other driftnet fisheries and set net fisheries distributed along the coastal line of Japan.
3. THE FISHERIES AND CURRENT HARVESTING METHODS
3.1 The harvesting process
The history of the expansion of the Japanese tuna longline fishing ground was well described by Suzuki (1988). Since the end of areal limitations on fishing by the US occupation force in 1952, the Japanese tuna longline fishery expanded their operations eastward reaching the eastern Pacific by the end of the 1950s (Figure 3). The fleet aimed at yellowfin tuna for export by the mid-1960s, and then gradually shifted the target to bigeye tuna for domestic fresh fish markets stimulated by demand from the recovery of the Japanese economy. Profitability of the bigeye tuna fishery in the cold waters drove the longliners toward higher latitudes along the American continents up to Lat. 30°N and Lat. 30°S by 1970. To harvest the deep swimming layer of bigeye tuna, the fishermen began to set their longlines deeper than before in 1975, thus reducting fishing effort for yellowfin tuna (Suzuki et al. 1977).
Following the Japanese longliners, Taiwanese and Korean longliners came to the eastern Pacific Ocean. These fleets are interested in albacore and bigeye tuna rather than yellowfin tuna in offshore and southern areas, mainly west of Long. 120°W and south of the equator.
Japanese squid driftnet fishing area (above) and large-mesh driftnet fishing area (below)
Schematic map showing the historical expansion of Japanese longline fishing grounds (Suzuki 1988) Numbers in the figure denote last digits of calendar year.
The Japanese distant water tuna longline fleet more recently focuses on bluefin, southern bluefin and bigeye tuna, which have high market values and their fishing grounds are concentrated in several areas in the oceans. The industrial Japanese salmon fishery began in 1894 on the south coast of Kamchatka peninsula using set nets. Salmon driftnet fishery started in 1931 and the number of vessels rapidly increased up to 200 in 1939. Then it was halted during the World War II and restarted in 1952. The fishing rapidly expanded in the high seas of northern North Pacific Ocean after restarting; however, this fishery has been under a moratorium since the end of 1992. The following two driftnet fisheries also stopped their operations on the high seas.
Yatsu et al. (1993) described the history of Japanese squid driftnet fisheries. Fishing for flying squid (Ommastrephes bartrami) started in 1974 when fishermen began jigging off the Pacific coast of Japan. Driftnet was introduced in 1978 and was found to be much more effective than jigs in catching large flying squid. Thus, jigging effort decreased and driftnet fishing effort and catch rapidly increased. The annual flying squid catch by jigging was about 124 000t in 1978, and gradually decreased to about 20 000t in the late 1980s. The rapid expansion of the squid driftnet fishery was also influenced by a combination of: (1) the decline of the distant-water fisheries, especially the salmon driftnet fishery in the late 1970s and early 1980s mainly due to the exclusion of Japanese fleets from the 200-mile zone of many countries; and (2) discovery of squid driftnet fishing grounds in the high seas of the North Pacific.
The number of squid driftnetters was estimated to be over 800 in November 1978. This resulted in a conflict over the fishing area with the existing jigging fishery. To avoid this conflict, the Japanese Government separated the grounds for these fisheries at 170°E longitude in 1979. Although the number of vessels decreased from over 800 in 1978 to 534 in 1981, the driftnet catch rapidly increased in early 1980s. This presumably resulted from the development of new fishing grounds and from the increased size of vessels. In response to the rapid increase in fishing effort and catch, the Government established a limited entry system for the squid driftnet fishery in 1981.
Nakano et al. (1993) describes the general history of the Japanese large-mesh driftnet fishery. The Japanese large-mesh driftnet fishery started in the 19th century in the coastal waters of Japan. The modern large-mesh driftnet fishery, starting in the 1970s and gradually expanded to offshore waters in the North Pacific Ocean. This fishery changed its target from striped marlin (Tetrapturus audax), in early stages of development, focusing on albacore (Thunnus alalunga). The Government of Japan took regulatory measures for the large-mesh fishery in 1973 by issuing a ministerial ordinance and notice. These measures were designed to effectively regulate this fishery and to solve gear conflicts with coastal fisheries or skipjack pole-and-line and tuna longline fisheries. Further, in 1982, in order to avoid the potential incidental catch of salmonids in the North Pacific, time and area closures similar to that for the squid driftnet fishery was implemented.
Trawl fishery operating in the East China Sea started in 1908. It developed rapidly and the number of fishing boats reached 139 in 1914. Then the government limited its fishing ground to the area west of 130°E, i.e. mainly the East China Sea. After decline of the fishery during the World War II, it rapidly expanded and number of boats reached 856 in 1947. The government reduced the number of fishing boats in 1950 and again in 1971 by 15%. According to this measure, total catch of this fishery should have been decreasing. Since the fisheries of China and Korea operated this fishing ground, the fishery was managed by fishery agreements established between the Government of Japan and China in 1955 and between Japan and Korea in 1965.
The other trawl fishery operates along the coast of the Tohoku district, from Chiba to Aomori prefectures and around Hokkaido. This fishery developed in the same period as the fishery in the East China Sea and also experienced a reduction of number of fishing boats through government measures.
The other major fishery catches elasmobranchs incidentally in the set net fishery. The set net fishery consists of salmon set nets, large scale set nets and small scale set nets which are located around the Japanese coast. These fisheries catch migrating yellow tail, and are distributed around Japan. In 1977, the numbers of set nets around Japan were 664 for salmon, 779 large scale set nets and 13 300 of small scale set nets. As these set net fisheries occasionally catch elasmobranchs; due to the huge number of set nets they contribute a significant portion of elasmobranch landing.
3.2 Evolution of catch
Figure 4 shows the historical catch of tuna and sharks caught by tuna longline fisheries. Following statistical figures were published by the Ministry of Agriculture, Forestry and Fisheries (MAFF 1977a–1997a). The total catch of tuna longline fisheries are relatively stable, although it shifted the catch level between 300 000 and 350 000t to a level between 250 000 and 300 000t. The landing of sharks increased from 24 000t in 1975 to about 30 000t in 1980 and it decreased to 13 000t in 1995. The proportion of sharks landing to the total catch was between 4.6 and 8.1 % during the periods.
The total catch of driftnet fisheries rapidly decreased after 1990 from about 17 200t to about 3400t in 1995 due to the decline in number of fishing vessels (Figure 5). The shark landings of driftnet fisheries gradually decreased during the periods. Now, the coastal driftnet fishery contributes the major part of the landings rather than the high seas driftnet fisheries.
The total catch of the trawl fishery operating in the East China Sea continued to decrease, from around 200 000t in the late 1970s to less than 5000t in 1995 (Figure 6). The landing of rays shows a drastic decline after the peak of 5300t in 1980. In 1995, the landing of rays was less than 500t. The landing of sharks also decreased substantially from the peak of 1093t in 1976 to 46t in 1995.
The landings of other trawl fisheries, mainly operating around the northern Japan shifted from a level of around 1 200 000t in the late 1970s and early 1980s to the level of 900 000t from the middle of 1980s (Figure 7). The landing of sharks revealed a gradual decline during these periods. The landing of sharks caught by the trawl fishery decreased from the peak of about 10 000t in 1975 to 1523t in 1995. The landings of batoids showed fluctuation between 800t and 1600t, but indicated neither a decreasing nor increasing trend during these periods.
3.3 Fleet characteristics, evolution of the fleet and fishing effort
Tuna longline vessels are classified into three categories by vessel size: (1) distant water, (2) offshore and (3) coastal longliners. The distant water tuna longline boats are usually larger than 120 GT and small number of boats less than 120 GT. The size of the offshore longliners is mainly from 50 to 100 GT. The coastal longline boats are less than 20 GT. The total number of tuna longline fishing vessels has decreased during the two decades mainly due to the decline in number of distant water and offshore longliners. The distant water longline fishery decreased from a peak of 892 vessels in 1981 to 744 in 1995 (Table 2). Offshore longliners also decreased from a peak of 637 vessels in 1980 to 222 in 1995. The number of the boats used in the coastal tuna longline fishery has fluctuated between 523 and 827 during this period.
The number of boats used in driftnet fisheries is shown in Table 2. The boats used in the coastal driftnet fishery categorised into four groups: (1) boats without engine, (2) less than 5 GT, (3) from 5 to 10 GT, and (4) larger than 10 GT. The size of boats in the salmon driftnet fisheries operating within the EEZ has two modes, between 100–150 GT, and 250–350 GT. The large-mesh driftnet fishermen use the boats up to 500 GT in size. Many boats are in 10–50 GT and 100–200 GT. Total number of boats operating the driftnet fisheries decreased from 680 in 1990 to 92 in 1996.
Several types of fishing boats are used in the trawl fisheries. The size of vessels operating in the East China Sea is about 150 GT. The other trawl fisheries operating around Japan are classified into offshore trawl fishery and small-scale trawl fisheries in which the vessel size is smaller than 15 GT. The number of vessels operating in the East China Sea is continuing to decease, from 218 in 1975 to 59 in 1995 (Table 2). The number of vessels in the offshore trawl fishery and small-scale trawl fisheries has also decreased during the two decades.
Total catch of Japanese tuna longline fishery (above) and shark catch by tuna longline fishery (below)
Total catch of Japanese drifnet fisheries (above) and shark catch by the fishery (below)
Total catch of Japanese trawl fisheries operating in the East China Sea (above) and catch of sharks
Total catch of offshore and small-scale trawl fisheries (above) and elasmobranch catch by the fishery
|Year||Tuna longline||Driftnet||Trawl||Small trawl|
|Distant water||Offshore||Coastal||Squid||Large mesh||East China Sea||Single trawl||Twin trawl||Small trawler||Other trawl|
The major landing ports for elasmobranch landings are listed in Table 3 based on the Annual Report of Fisheries Distribution (MAFF 1993b–1997b) and their locations are shown in Figure 8. Shark landings were classified into fresh, chilled and frozen meat. In regards to major landing ports for fresh or chilled shark meat, Hachinohe and Choshi are the mother ports of the northern trawl fishery. Major landed species are spiny dogfish and Mustelus spp. Kesennuma and Katsuura are base ports of coastal and offshore tuna longline fisheries and these fisheries sometimes target sharks. The major landed species are pelagic. Nagasaki is the mother port of the trawl fishery, which operates in the East China Sea. The major species landed here are benthic sharks and rays. Frozen shark meat is landed by distant-water longliners. Misaki and Shimizu are major ports for distant-water tuna longliners. Landed species are pelagic sharks. Kesennuma also has some frozen shark meat landings, however landings have declined after 1993. Wakkanai, Nemuro and Kushiro are mother ports for the trawl fishery around Hokkaido, northern Japan, which lands skates and rays. Main components of Batoids are Raja species. Shimonoseki and Nagasaki are base for trawl fishery operating in the East China Sea. Stingrays, Dasyatisspp. are major components of batoid bycatch. The following descriptions of utilisation for shark products are from Kiyono (1996).
|Kesennuma||13 981||14 172||15 034||12 758||12 712|
|Others||1 579||1 711||1 183||1 000||904|
|Total||18 248||18 498||18 376||15 428||15 136|
|Shimizu||1 854||1 037||1 085||917||912|
|Total||3 505||2 492||1 531||1 336||1 253|
|Skate and rays|
|Total||2 833||2 545||2 642||2058||1823|
Landed meats are utilised in several forms, e.g. fresh meat, “surimi” and processed meat. Some species caught by tuna longline fisheries are used for domestic consumption as meat except for the blue shark which is not suitable to be used as either fresh or frozen meat, but can be used as raw material for processed foods such as “surimi”. Some of the landings of frozen shortfin mako shark meat are exported, mainly to the EU.
Location of major landing ports of elasmobranchs in Japan
Spiny dogfish, Smooth hounds (Mustelus spp.), swell sharks (Cephaloscyllium spp.) and webbegongs (Orectolobus spp.) caught by trawl and coastal fisheries are eaten in “Sashimi” and boiled meat in local areas. Spiny dogfish is also sold grilled in Shiogama, the northern part of Japan. Batoids are utilised for domestic consumption either fresh or processed.
Shark fins from many species are consumed in domestic or export markets. Fins are removed from the shark on board, in markets or factories. Large amounts of fins are removed at Kesennuma port and the meat sold. The major part of distant-water longliners bring at least shortfin mako shark meat, some bring a variety of species. Factories process fins supplied by fisheries and some fins are exported for processing, i.e. peeling skin and drying for re-export to Japan.
There are statistics of shark fin products in Kesennuma City, the largest shark landing port in Japan (Table 4). Shark fin products are classified as dried, boiled and dried, freeze-chilled, and frozen fin. The peak production of dried fin product was 634t in 1988, then it decreased slightly. The price of dried shark fin, 4890 ¥/kg, was highest in 1993. The highest price and year for the product categories of boiled and dried fin, freezen/chilled fin and frozen and dried fin were 25 380 ¥/kg in 1992, 7220 ¥/kg in 1992 and 7194 ¥/kg respectively. These prices seemed to be determined mostly by the high cost of processing.
The shark foin dealers supply processed fins primarily to the domestic market though some are exported to foreign markets. Some processed fins are imported from Brazil and Chile. The shark fins landed at Shimizu Port consisted of those from blue shark (70%); about 90% of these products are exported to Hong Kong and Singapore.
Shark liver oil contains squalene and vitamin A. Squalene is used in cosmetics and health foods. Liver oil is used for lubricating oil. Deep-sea sharks, Gulper shark (Centrophorus atromarginatus), and Roughskin shark (Centroscymnus owstonii) have much liver oil and are used for oil products. The liver of Basking Shark (Cetorhinus maximus) which is incidentally caught by set net fishery is also used. Kiyono (1996) reported the results of their interviews with Japanese cosmetics companies. One company reported that the annual import of squalene was about 10t. However synthetic squalene is also used, and the reported amount of squalene extracted from sharks is unknown.
Japan was one of the largest export countries of shark oil in the world (Tarumoto 1984). Suruga Bay and Sagami Bay, located in the central part of Japan, were famous fishing grounds fo deep-sea sharks. The demand for liver oil as a lubricant increased during World War II. After World War II oil was used as health food. There is no information on deep-sea shark catch during World War II.
Shark cartilage contains chondroitin and, although not used in traditional medicine, is used in western medicine for the treatment of eye fatigue and rheumatism. Shark cartilage is also reputed to be an effective preventive medicine against cancer. Such claims, although not scientifically proven, have resulted in increased demand for shark cartilage. Cartilage from the blue shark is believed to contain high levels of chondroitin. Cartilage is obtained from the shark fin dealers who sell it to wholesale dealers. After the wholesale dealers have dried the branchial gills and vertebrae, the dried product is sent to pharmaceutical factories.
Some sharkskin is used in Japan to produce leather products, i.e. handbags belts, watchbands, etc. Japanese used sharkskin as pieces of armor and sword grips. Some shoes were made from sharkskin during World War II. Skins are also used to produce the “Nikogori”, Japanese traditional gelatinous food.
3.4.2 Revenues from the fishery
As mentioned above, Japanese sharks landing continued to decline from 1956 to 1995. Although the landing of batoids also decreased, it was relatively gradual. The reasons for these declines are presumably a combination of overexploitation, reduction of fleets and decreased demand. In fact, the consumption of elasmobranchs is decreasing due to a change in dietary preferences.
Only export statistics of shark fin are available for the Japanese shark fin trade from the FAO statistics (Table 5). The amount of shark fin exports peaked in 1981 at 1073t, then declined; in 1995 it was only 380t.
Kiyono (1996) reported statistics on shark liver oil production in Japan (Table 6). Although the data for some years, and the year after 1981, were not available, the amount of production begun to decline in the 1970s. The statistics of utilisation on shark cartilage and skin are unavailable.
|Year||Production||Dried amount of money||Market price||Production||Boiled and dried amount of money||Market price||Production||Frozen amount of money||Market price||Production||Frozen and dried amount of money||Market price|
|(tonnes)||('000 ¥)||(¥/kg)||(tonnes)||('000 ¥)||(¥/kg)||(tonnes)||('000 ¥)||(¥/kg)||(tonnes)||('000 ¥)||(¥/kg)|
|1983||203||769 180||3789||18||81 958||4 553|
|1984||185||672 506||3635||167||133 064||796||17||122 300||7194|
|1985||187||432 665||2310||23||115 000||5000|
|1986||176||422 685||2400||123||1 427 600||11 610||22||85 085||3870|
|1987||206||768 701||3730||43||538 039||12 560||160||120 000||750|
|1988||634||1 630 790||2570||40||576 146||14 550||123||253 861|
|1989||486||1 348 689||2775||14||300 795||21 485||180||472 365||2624|
|1990||588||1 325 989||2260||12||142 764||11 900||158||622 238||3950|
|1991||320||1 287 500||4020||13||208 578||16 040||135||405 938||3010|
|1992||395||1 329 727||3370||36||913 510||25 380||86||619 309||7220|
|1993||265||1 296 248||4890||40||871 938||21 850||187||856 632||4580|
|1994||275||1 171 500||4260||37||577 066||15 600||136||605 962||4460|
|Year||Shark fins exported|
|Year||Shark liver oil production (tonnes)||Year||Shark liver oil production (tonnes)||Year||Shark liver oil production (tonnes)|
|1935||no data||1958||2514||1981||no data|
|1936||no data||1959||3222||1982||no data|
|1937||no data||1960||3831||1983||no data|
|1938||no data||1961||2247||1984||no data|
|1939||no data||1962||2201||1985||no data|
|1940||no data||1963||1266||1986||no data|
|1941||no data||1964||1142||1987||no data|
|1942||no data||1965||1071||1988||no data|
|1943||no data||1966||948||1989||no data|
|1944||no data||1967||1131||1990||no data|
|1945||no data||1968||729||1991||no data|
|1946||no data||1969||1112||1992||no data|
|1947||no data||1970||no data||1993||no data|
3.5 Economics of the fishery
In general the Japanese fisheries have infrastructure problems. Since fishery is hard work and it is getting more difficult to get high wage from fisheries, younger generations are less inclined to become fishermen. Although there were lots of fishery villages, even in such places, few people now like to go into fisheries.
In the developing stage of the tuna longline fishery during the 1950s, wages of the tuna longline vessel crews were relatively high compared with ordinary blue-collar workers on land. It was said that even young recruits could have their own houses after three years of tuna longline work. However, this is an old story now. There are many reasons why this is no longer the case in the tuna longline fisheries. The declaration of EEZs by many countries has reduced the tuna fishing grounds. If tuna longliners wish to continue to fish in the EEZ of some countries, they must pay expensive entry fees. The stock statuses of tunas are about MSY, or below MSY in many species. Environmental issues, e.g. shark conservation, bycatch of sea birds, etc., result in additional costs to the industry. And, the difference in wages between sea and land labourers became very small. Thus, some fishing boats hire foreign crews to reduce labour costs. The last reason is that the tuna industry mostly consists of small fishing companies that have only a few boats, sometimes one or two. It is difficult for such companies to keep up with changes in the economical situation. These reasons together have made the tuna longline fishery barely profitable.
Of the driftnet fisheries, including salmon, squid and large-mesh driftnet fisheries, the details of management of such companies have not been published. The increasing regulation of the salmon driftnet fishery through international negotiation has made salmon fishing precarious and many salmon fishing boats have moved into another driftnet fisheries. After the ban of high seas large-scale driftnet fishing, thw government needed extra budgets to compensate the withdrawal of vessels from their fishery. Some of fishermen lost their jobs and some moved into tuna fisheries.
In the case of trawl fisheries including those operating in the East China Sea and northern parts of Japan, the number of boats rapidly increased after World War II. It made the financial situation of trawl fishing companies difficult and caused conflicts in the fishing ground. The government then reduced the number of fishing vessels through a compensation scheme. In addition, the decline of fish stocks in the East China Sea fishing grounds added to the difficulties of the financial performance of the industry.
There is insufficient information to discuss the economic situation of the other fisheries including set net fishery and small-scale coastal fishery,. However, the activity of these fisheries is relatively stable in comparison to the other industrial fisheries.
3.6 The fisheries workforce
The number of crew on a distant-water tuna longline boat is about twenty. The offshore and coastal tuna longline boats, both have more than 10 men on board. In 1995, the number of tuna longline boats in the distant water, offshore and coastal tuna longline fisheries were 744, 222 and 738 respectively. If the number of crew on each boat was assumed to be 20, 10 and 5, the total number of Japanese tuna longline fishermen in 1995 would have been 20 790. All were full-time professional workers. However, as mentioned above, some companies hire foreigners as crew. They are sometime part-time, but in some cases foreign fishermen are hired and trained in Japan or a foreign country.
The average number of crew on squid and large-mash driftnet fishing vessels is about 15–16 people. The number of vessels in each fishery was 463 and 459, respectively, in 1988. Thus about 14 000 full-time professional fishermen have been employed in the driftnet fishery-related industries. Although most of them have left these fisheries on high seas, some remain in fisheries inside the Japanese EEZ.
The total amount of employment in the trawl fisheries is not known, but all fishermen are professional full-time workers. There is no available information of employment in the other fisheries including set-net fishery and small-scale coastal fishery. These workers are all fishermen, but some are temporary workers in the set net fisheries, in many cases, coastal fishermen in small-scale fisheries The number of employment on the other small-scale fisheries is unknown.
4. MANAGEMENT OBJECTIVES
4.1 The fisheries within the context of national fisheries policies
Japan has two fundamental law relating to the management of fisheries. One is the Fisheries Law and the other is the Fishery Resources Protection Law. The aim of the Fisheries Law is to establish basic management systems for the fisheries using adjustment mechanisms of the fisheries societies. It provides for the fishing rights, licensing of the fishery, and the adjustment mechanism among fisheries. The aim of the Fisheries Resources Protection Law is to conserve fishery resources and to develop and maintain sustainable fisheries. To conserve marine resources, the law contains; (1) restriction or prohibition on taking aquatic animals and plants; (2) restriction or prohibition on sales or possession of aquatic animals and plans; (3) restriction or prohibition on fishing gear or fishing vessels; (4) restriction or prohibition on discarding or leaking materials which are harmful to aquatic lives and of causing water pollution which is harmful to aquatic lives; (5) restriction or prohibition on taking or removal of objects which are necessary for protection and propagation of aquatic animals and plants; and (6) restriction or prohibition on transplanting aquatic animals and plants.
In addition to the law mentioned above, Japan ratified the UN Law of the Sea. This treaty was issued in 1996. Following the ratification of the treaty, three new laws were established: (1) declaration of Japanese EEZ, (2) establishment of Total Allowable Catch (TAC) for some species, and (3) prevention of diseases for aquaculture species by importing.
Almost all participants in commericial fisheries require licences or are fisheries based on fishery rights. In the case of fishery rights, fishermen need certification from the prefectural administrative authorities. There are three types of fishery rights; set-net fishery rights, demarcated fishery rights, and common fisheries rights. Set-net fishery rights are the rights to operate a set-net fishery, fixed at a designated site. Demarcated fishery rights are the rights to operate aquaculture in a certain area. Common fishery rights can be defined as the right of fishermen in a given community to use specified waters as a common fishery.
A fishery licence is required for the operation of certain types of fisheries. Depending on the type of fishery involved, relevant administrative agencies at various levels of government may issue a fishery licence. A fishery licence is different from a fishery right. Many important fisheries are licensed fisheries. There are two types of licensed fisheries: the minister-licensed fisheries and the governor-licensed fisheries. The minister-licensed fisheries are designated by Japanese government ordinance. Major minister-licensed fisheries including the offshore trawl fishery, large trawl fishery in the Yellow Sea and East China Sea, pelagic skipjack and tuna fishery, medium-type salmon driftnet fishery and mothership-type of salmon fishery.
4.2 Objectives for the management of the shark fisheries
There is no particular management objective on shark. However, the Fisheries Agency of Japan instructed the tuna longline fishermen to bring back both fins and carcass together when they land shark fins.
4.3 The objective setting process
The Fisheries Law provides for fishery adjustment mechanisms. The Marine Fishery Adjustment Commission and the United Marine Fishery Adjustment Commission undertakes the role of adjustment on fisheries. A Marine Fishery Adjustment Commission is set up for each specified sea area. There are 65 areas in Japan. At the ministerial level, the national government has the Central Fishing Council as an advising organ. When a minister introduces new, or revised regulations, the minister refers them to the Council for deliberation.
The aim of the Fisheries Law is to establish basic management systems for the fisheries using adjustment mechanisms of the fisheries societies. Existing management systems for the fisheries mostly focus on maintaining productivity of the fisheries and avoiding and reconciling conflict among the fisheries. However effective operation of management systems focused on elasmobranchs needs more information related to their resource and ecological situation. The Fisheries Resources Protection Law focuses more on details of conservation of aquatic species. In addition with those fundamental laws, new laws including (1) declaration of Japanese EEZ, (2) establishment of Total Allowable Catch (TAC) for some species, and (3) prevention of diseases for aquaculture species by importing were established. The TAC system, especially, works for conservation of marine resources.
5. MANAGEMENT POLICIES AND THE POLICY SETTING PROCESS
5.1 Identification and evaluation of policies
Following the principles provided by the Fisheries Law and the Fishery Resources Protection Law, the Marine Fishery Adjustment Commission, the United Marine Fishery Adjustment Commission, the Fisheries Agency of Japan issued several regulations and prohibitions. These included time-area closure of fisheries, limited entry systems of the fisheries, gear restrictions, and restrictions on vessel size. In addition to these, the Fisheries Agency of Japan also instructed fishermen to obey regulatory guidance for some fisheries and adopted international fisheries organisations' regulations.
5.2 Policies adopted
5.2.1 Resource access
The number of fishing licences issued by the government for the distant water tuna longline fisheries was limited. The number of the boats in the offshore and coastal tuna longline fisheries was also limited. Certain fishing grounds of the distant water tuna longline fishery, i.e. the southern bluefin tuna fishing grounds and northern bluefin tuna fishing grounds in the North Atlantic Ocean also have limited licences under government order.
There were strict regulation regarding the large-scale driftnet fisheries in high seas for time-area closures, mesh size and limited entry. For the trawl fisheries operating around Japan, these fisheries have strict regulation including a limited entry system, vessel size limitation, time and area closures, fishing gear limitations and the number of their vessels has been reduced twice by the government.
The government has controlled the number of boats operating in the distant water fisheries including tuna longline fisheries and high seas driftnet fisheries. Since high seas driftnet fisheries went into the moratorium, the prefectural governments have taken the role of management of driftnet fisheries operating inside the Japanese EEZ.
The trawl fisheries are licensed fisheries managed by the prefectural and central governments, so the government has controlled the number of boats and fishing conditions of the fisheries by issuing a limited number of licences. The other fisheries are also restricted by the prefectural governments that control such fisheries.
5.2.2 Gear restrictions
The salmon driftnet fishery regulation specifies a minimum stretched mesh size of 91 mm in Japan Seas. Nakano et al. (1985) estimated the selectivity of salmon driftnets on blue shark. Following the implementation of the mesh size regulation, the fisheries mainly caught only one to two year classes of blue shark. The other fishery regulation was mandatory marking of fishing gear for identification. Each driftnet vessel was requested to use marked gear to identify the driftnetters who deployed the gear. Each vessel is also required to refrain from discarding used or damaged driftnets, to stow them on the vessel and to return them to port for proper disposal after completion of the vessel's cruise. The location, date, and amount of lost fishing gear must be reported to the government.
The large-mesh driftnet fishery also had the same kind of gear management as the salmon driftnet fishery. Large-mesh driftnet vessels were allowed to carry gear that had a mesh size of at least 150mm. Some trawl fisheries have mesh size restrictions by the target species. For instance the trawl fishery operating in the East China Sea introduced mesh size restrictions of 54.5mm in 1963.
5.2.3 Vessel regulations
Tuna longline fisheries have been classified into three types terms of their GRT. Vessels larger than 80 GRT are classified as distant-water tuna longline; those between 20 GRT and 80 GRT are called offshore tuna longliners. Vessels less than 20 GRT are classified as coastal tuna longliners.
5.2.4 Biological regulations
Generally, there are no particular biological regulations in fisheries for elasmobranchs. However, the Fisheries Agency instructs large distant tuna fishing boats to record shark bycatch and to bring back carcass as far as possible. Several biological regulations have also been introduced relating to other species. For example, swordfish caught by tuna longline fishery in the Atlantic Ocean has minimum size limit set by ICCAT.
5.2.5 Catch/quota allocation
Japan declared its EEZ in 1996 following the ratification of the UN Law of the Sea, following which TACs for major target species of the fisheries were set. However, specific no catch/quota allocations are not set for elasmobranchs.
Almost Japanese fisheries have limited entry systems and each fishery is subject to various regulations including time-area closures, regulation of gear, vessel size regulations, etc. Although those regulations do not focus on managing elasmobranch stocks, they will contribute to the conservation of the elasmobranch stocks.
6. THE MANAGEMENT PLANNING PROCESS
6.1 Provision of resource management advice
There are seven National Institutes of Fisheries in Japan. Each Institute has a fishery management advisory council on the stock status of certain species, which report on an annual bases and stock statuses are reported to the government. If it is desired, the council will recommend management measures to the fishery management. However, elasmobranch species are not included in the management framework of the council.
So far there is no mechanism for provision of resource management advice on elasmobranchs in Japan. If it was desired, the fishery management advisory councils can include such species in their mandate.
6.2 Fishery statistics
6.2.1 Methods used for collection of catch and effort data
The licences issued by the minister to fisheries such as the distant water, offshore tuna longline, high seas driftnet and trawl fisheries requests fishermen to submit logbook reports to the government. Each National Research Institute of Fisheries compiles the logbook reports of the fisheries they have responsibility for. The database compiled for each fishery is used for stock assessment. The logbook reports include catch by species and fishing effort. In some cases, elasmobranch catch is compiled into the group of sharks and rays. The governor-licensed fisheries, including coastal tuna longline fishery and small-scale trawl fishery, also must submit logbook reports.
Besides logbook reporting system, the statistics and information department of the Ministry of Agriculture, Forestry and Fisheries (MAFF) assesses the landing of fisheries by a census of fishermen and fishing markets. They publish two kinds of fisheries statistical bulletins, one is the Annual Statistics of Fisheries and Aquaculture Production; the other is the Annual Statistics of Fishery Products Marketing. However, those two bulletins only compile the landings of elasmobranchs into two or three categories. The Annual Statistics of Fisheries and Aquaculture Production has two categories of elasmobranchs landings, sharks and batoids. The Annual Statistics of Fisheries Distribution has three categories, sharks fresh or chilled, frozen sharks and batoids.
6.2.2 Evaluation of the data collection process
The coverage of logbook data is generally high. For example, in the case of distant water tuna longline fishery, the logbook coverage is more than 90%, although the coverage of logbook reports of the coastal tuna longline fishery is significantly lower. The accuracy of the data is another problem, but in some cases including the tuna longline and high seas driftnet fisheries, the data have been evaluated by comparing the data of research cruise with that of the commercial fisheries' observer data.
The problem of the landing statistics is it is hard to divide the data compiled into groups back into species while it is necessary to collect the landing data of elasmobranchs by species. The government requires the collection of elasmobranchs' landing data by species only for the tuna longline fisheries.
6.2.3 Data processing and storage and accessibility
The logbook data are verified and compiled by each National Research Institute of Fisheries. Data are in storage in the electronic form and published. In many cases the Institute asks a private data processing company to input and compile the data. Since the data includes private information of each vessels, i.e. the position of fishing operations, etc., the distribution of the publication and access to the original data are limited.
The data describing the fisheries statistics landings and distribution are compiled and stored by the Statistics and Information Department of the Ministry of Agriculture, Forestry and Fisheries in electronic form. The department also publishes two types of statistics bulletins. These publications, the Annual Statistics of Fishery and Aquaculture Production and the Annual Statistics of Fishery Products Marketing are widely distributed.
6.3 Stock assessment
6.3.1 Measures of stock abundance
In the case of the tuna longline fisheries, the Fishery Agency of Japan uses a revised logbook reporting form that acounts for four categories of shark catch, i.e. blue shark, salmon shark, shortfin mako shark and other sharks. The shark research programme, uses about thirty research and training vessels and has been conducted since 1992. Also an observer programme including shark research has started in the southern bluefin tuna fishing ground mostly in the Indian Ocean since the 1992. In addition to those research activities, the National Research Institute of Far Seas Fisheries started a shark tagging programme from 1996. Stock assessments for the pelagic sharks caught by the Japanese tuna longline fisheries have been conducted using those data.
The high seas driftnet fisheries provide catch and effort data by species submitted through a logbook report. They also had observer programmes and there were several research cruises in the last stage of the history of the fishery. Preliminary assessments on the stock status of elasmobranchs caught by the fisheries were done in 1991. However these fisheries ceased before the collection of enough data for an assessment. The trawl fisheries also provide catch and effort data from the logbook reports and research activities. However, assessments of elasmobranch stocks have not been done yet.
Stock status is assessed by catch per unit effort, i.e. number of catch per certain units of hooks for the elasmobranchs caught by tuna longline fisheries. However, the configuration of the longline fishing gear has been changed, i.e. the number of hooks between floats on the longline. Fishermen have also adjusted the depth of longline hooks and changed the number of hooks between floats. Therefore the historical change of gear design should be considered in estimating the catch per unit effort.
For the high seas driftnet fishery, catch and effort data, and number of catch per unit net or length, were used for assessments. The selectivity of mesh size on elasmobranch catches should be considered for analysis in the driftnet fishery.
6.3.2 Biological advice review process
Biological data of pelagic elasmobranchs caught by tuna longline fisheries has been collecting since 1992. Since CPUE effort analysis for pelagic species did not show drastic changes, biological advice has not made yet been given. For the high seas driftnet fisheries, trawl fisheries and other fisheries, biological advice likewise has not been given.
6.3.3 Biological management reference points
There are no biological management reference points for elasmobranchs in Japan.
6.3.4 Sustainability of the resource
It is considered that the stock statuses of the pelagic species caught by tuna longline and high seas driftnet fisheries that exploited the same pelagic stocks are relatively healthy. From the point of view of recent assessment results, Matsunaga and Nakano (1996), Nakano (1996) and Nakano (1997) reported nominal and standardised CPUE for pelagic elasmobranch species and found no drastic changes in CPUE were evident during the two decades.
The quantity of rays and sharks caught by the trawl fishery in the East China Sea revealed drastic declines during the past two decades (Figure 6). The quantity of spiny dogfish and skates caught by trawl fisheries along the coasts of Tohoku region and Hokkaido, both northern parts of Japan, show a gradual decrease of abundance for those caught around Hokkaido and indicates a decline of abundance to one third original biomass during the last fifteen years. The quantity of spiny dogfish caught along the coast of Tohoku region declined in one area and was relatively stable in the other area. The stock of spiny dogfish probably decreased and became stable at a low level.
The landing of spiny dogfish caught in the northern part of Japan drastically decreased in the 1950s, and continues to decrease. Taniuchi (1990) pointed out that the cause of decreasing of spiny dogfish landings was possibly due to the overexploitation of the species and decrease of demands in the markets. With regard to sustainability of elasmobranchs of benthic and coastal species, lack of fishery statistics on a species basis makes it difficult to evaluate status of those species accurately.
126.96.36.199 The manager's perspective
On the pelagic fisheries, there is research, observer programmes and logbook reporting systems, that details shark catch by species. Several assessments are conducted for some species. However, other fisheries operating in the EEZ of Japan make relatively little effort to collect statistics on elasmobranchs. It is desired to collect continuously the catch and effort statistics by species of elasmobranchs in each fishery. And assessments, focusing on stock status of elasmobranchs, are also desired.
188.8.131.52 Users' perspective
Generally fishermen and industries do not welcome any kind of regulations, because they become the cause of extra costs, extra workload and make fishery operations more complex, although, fishermen and industries usually cooperate in the research conducted by the government. Elasmobranchs generally have low value for the fishermen and fishermen do not pay much attention to such species. Public education and instruction by the government of the industries is necessary to collect enough statistical data for stock assessments of elasmobranchs.
184.108.40.206 Evaluation of the management process
Although the Fisheries Agency of Japan has several Fishery Management Advisory Council under the Council of Fishery Research and Study, each council focuses more on important fish species. Those councils should consider about research and study of less important species whose sustainability is in question, including elasmobranchs. See also Section 5.
7. THE LAW AND ENFORCEMENT
7.1 Legal status
The Fisheries Law regulates fishery rights in Japan. The aim of the Fisheries Law is to establish basic management systems for the fisheries using adjustment mechanisms of the fisheries sector. The Fisheries Law includes three major components: (1) fishery rights, (2) fishery licences, and (3) fishery adjustment mechanisms. Fishery rights are the rights to operate certain types of fisheries in designated waters. Fishermen need certification from the prefectural government, when they exercise such exclusive rights of fishing. There are three types of fishery rights, for set-nets, demarcated rights, and common fisheries rights. Set-net fishery rights are the rights to operate set-net fishery fixed at a certain site. Demarcated fishery rights are the rights to operate aquaculture in a designated area. Common fishery rights can be defined as the right of fishermen in a given community to use designated waters as a common fishery. Local fishery co-operative associations establish rules for fishery rights, and management of fishery rights by controlling fishing areas, periods, and fishing methods.
A fishery licence is required for the operation of certain types of fishery. Depending on the type of fishery involved, relevant administrative agencies at various levels of government may issue a fishery licence. A fishery licence is different from a fishery right. Issuing the licence is legally interpreted as an administrative action lifting a ban where fishing has been prohibited with the view of conserving the fishery resources and ‘adjustment’ of fisheries interests.
Many important fisheries are licensed fisheries. There are two types of licensed fisheries, which are the minister-licensed fishery and the governor-licensed fishery. The minister-licensed fisheries are designated by the Japanese Government ordinance. Major minister-licensed fisheries are the offshore trawl fishery, large trawl fishery in the Yellow Sea and East China Sea, mothership-type whaling, pelagic skipjack and tuna fishery, medium-type salmon driftnet fishery, mothership-type of salmon fishery.
The Fisheries Law is established to develop fishery productivity and democratise fisheries. The fishery manager and fishery employees have formed a democratic fishery adjustment mechanism. There are two kinds of commissions to execute the mechanism; the Marine Fishery Adjustment Commission, and the United Marine Fishery Adjustment Commission. A Marine Fishery Adjustment Commission is set up for each specified sea area. There are 65 such areas in Japan.
The Fishery Resources Protection Law was established in 1951. The purpose of the law is to protect and propagate fishery resources, and develop sustainable fisheries. Some of the regulations arising from the law are as follows: (1) restriction or prohibition of taking aquatic animals and plants, (2) restriction or prohibition on sales or possession of aquatic animals and plants, (3) restriction or prohibition on fishing gear or fishing vessels, (4) restriction or prohibition on discarding or leaking materials which are harmful to aquatic lives and of causing water pollution which is harmful to aquatic lives, (5) restriction or prohibition on taking or removal of objects which are necessary for protection and propagation of aquatic animals and plants, and (6) restriction or prohibition on transplanting aquatic animals and plants. Each metropolitan and prefectural government has enacted the Fishery Adjustment Regulation for implementing detailed regulatory measures under the Fisheries Law and the Fisheries Resources Protection Law.
7.2 Enforcement problems
Since no regulations focusing on elasmobranchs are set, any problems relating enforcement of regulation is not identified.
The Fisheries Agency of Japan has several inspection boats to observe and regulate the fishery operations. The Agency also has a fishery adjustment office around Japan.
7.4 The legal process
Any person who has fished in violation of The Fishery Law and The Fisheries Resources Protection Act shall be subject to an imprisonment or a fine. They lose their licence by the order of the government or prefectural government.
8. MANAGEMENT SUCCESS
8.1 Profitability of the fishery
Japan is one of the largest fishing countries all over the world and the fishery industry is still important for the people of Japan. The total fishery production in 1994 was 8 100 000t, about US$ 20 billion (1$=120¥). This productivity sustains many fishery sectors including those of harvesting, wholesale, processing and etc.
8.2 Issues of equity and efficiency
Each Fishery Management Advisory Council executed by a National Research Institute of Fisheries and relating organisation can accept the attendance of observers. Petitions to the government are considered quite often for different problems. However, the Establishment Council of TAC does not accept observers in their meetings.
9. MANAGEMENT COSTS
The National Research Institutes of Fisheries and the operation of research vessels needs governmental budgets to fund their activities. Several chartered fishing boats are also used for research. In addition of these activities, each prefectural government has a fishery research station, research vessels, and fishery training vessels. National Research Institutes of Fisheries belong to the government and fishery research stations belong to the prefectural government, they mainly take the responsibility for stock assessment.
The Fisheries Agency of Japan, Fishery Division of prefectural governments, the Marine Fishery Adjustment Commission, the United Marine Fishery Adjustment Commission and the Fishery Management Advisory Council are charged with the mandate management planning. The Fisheries Agency of Japan and the prefectural governments have inspection boats and Fishery Adjustment offices, which are charged with enforcement of fishery regulations. All these organisations are sources of cost for fishery management. Cost-recovery management has not yet been undertaken.
10. LITERATURE CITED
Bonfil, R. 1994. Overview of world elasmobranch fisheries, FAO Fisheries Technical Paper 341, FAO, 119pp.
Kiyono, H. 1996. TRAFFIC report on shark fisheries and trade in Japan. The world trade in sharks: a compendium of TRAFFIC's regional studies, volume I: 145–197.
MAFF (Ministry of Agriculture, Forestory and Fisheries of Japan) 1977a–1997a. Annual Statistics of Fishery and Aquaculture Production. MAFF, Statistics and information department.
MAFF 1977b–1997b. Annual Statistics of Fishery Products Marketing. MAFF, Statistics and Information Department.
Matsunaga, H. and H. Nakano 1996. CPUE trend and species composition of pelagic shark caught by Japanese research and training vessels in the Pacific Ocean. Information paper submitted to the 13th CITES Animals Committee, Doc. AC. 13.6.1 Annex, 8pp.
Nakano, H. 1996. Distributions of pelagic elasmobranchs in the North Pacific Ocean. Resources and Conservation of Elasmobranchs, Kaiyo Monthly, 28(7): 407–415. (In Japanese)
Nakano, H. and K. Shimazaki 1989. Gill net mesh selectivity for the blue shark (Prionace glauca L.), Bull. Fac. Fish. Hokkaido Univ. 40(1): 22–29.
Nakano, H. 1997. Standardized CPUE for shark caught by Japanese longline fishery in the Atlantic Ocean. Working document submitted to the ICCAT SCRS in 1997, SCRS/97/34, 10pp.
Nakano, H. 1996. Histrical CPUE of pelagic shark caught by Japanese longline fishery in the world, Information paper submitted to the 13th CITES Animals Committee, Doc.AC.13.6.1 Annex, 7pp.
Nakano, H.,K. Okada, Y. Watanable and K. Uosaki 1993. Outline of the large-mash driftnet fishery Japan. In I. Driftnet fisheries of the North Pacific Ocean. (J. Ito, W. Shaw and R.L. Burgner eds.), INPFC Bull. 53(I): 25–37.
Suzuki, Z. 1988. Study of interaction between longline and purse seine fisheries on yellowfin tuna, Thunnus albacares (Bonnaterre). Bull. Far Seas Fish. Res. Lab., 25: 73–144.
Suzuki, Z., Y. Warashina and M. Kishida 1977. The comparison of catches by regular and deep tuna longline gears in the western and central equatorial Pacific. Bull. Far Seas Fish. Res. Lab., 15: 51–89.
Taniuchi, T. 1990. The role of elasmobranchs in Japanese fisheries. In Elasmobranchs as living resources: Advances in the biology, ecology, systematics, and the status of fisheries (H.L. Pratt, S.H. Gruber and T. Taniuchi, eds.), NOAA Technical Report NMFS 90: 415–426.
Tarumoto, R. 1984. History and status of sharks fisheries focused on the offshore sharks longline. Report of Japanese group for elasmobranch studies. 17: 6–28.
Yatsu, A., K. Hiramatsu and S. Hayase 1993. Outline of the Japanese squid driftnet fishery with notes on the bycatch. In I. Driftnet fisheries of the North Pacific Ocean. (J. Ito, W. Shaw and R..L. Burgner eds.), INPFC Bull. 53(I): 5–24.