4. DEMERSAL FISH FISHERIES AROUND JAPAN

4.1 Environment and Total Catch

The continental shelf (shallower than 200 m) around Japan is narrower than those in neighbouring seas, and has an area of about 424 000 km², compared to about 620 000 km² for the Okhotsk Sea and ambout 940 000 km² for the Yellow Sea to East China Sea (see Figure 3). Even when the continental slope area, ranging from 200 to 500 m in depth (128 000 km²) is taken into account, the total area available for demersal fish fisheries is very small at about 552 000 km². However, the total catch of demersal fish taken from these narrow waters has been substantial at about 1.8 million tons annually in recent years.

Figure 3. The extent of the continental shelf area (shallower than 200 m) in the waters around Japan and adjacent seas.

The total catch increased steadily from 1968 to 1977 from about 1.2 to 1.8 million tons. This was achieved chiefly by larger catches of Alaska pollack and sandlance (both fish of low commercial value) from the northern waters, i.e. the Okhotsk Sea, the northwestern Pacific along the Japanese coast, and the northern Japan Sea. The increase in the catch of these fish was stimulated by the increased demand for raw material to produce minced-meat (“kamaboko”) for the former species, and for feeding material for aquaculture for the latter (see Subsection 6.4 for an example of the latter).

A variety of species are included in the total catch, including sharks, skates, bastard halibut and other flounders, plaices and soles, Pacific and saffron cods, Alaska pollack, Atka mackerel, Japanese sandfish, rockfish, sculpins, Japanese argentine, Japanese butter fish, daggertooth pike-conger, largehead hairtail, croakers, lizardfish, red and crimson sea breams, black and yellow sea breams, threadfin breams, tilefish, grunters, gurnards, perches, sandlance, gobies, pony fish, flathead, sea robin, filefish, various prawns and shrimps, crabs, cuttlefish, squids and octopuses. In Japan, the numbers of demersal fish species commonly sold in wholesale markets exceeds 250, most of which are taken from various types of multispecies demersal fish resources distributed around Japan. These are summarized below.

Much of the total catch has been taken from the northern fishing grounds. For example, in recent years about 30 percent of the total demersal fish catch has been taken from the waters along the northeast coast of Hokkaido bordering the Okhotsk Sea (see Figure 1 for the location of the region). This is due first to the large abundance of several boreal species in the northern fishing grounds and second to the high density of those stocks. Table 3 shows this clearly.

4.2 Species composition

The species composition of the catch differs greatly by region, and the number of species involved is generally smaller in the north and larger in the south. They are summarized as follows;

4.2.1 Pacific Ocean (see Figure 1 for the region)

Hokkaido, northeast;

Most of the catch is composed of three major species, i.e. Alaska pollack, sandlance and Atka mackerel. The combined catch of these species usually accounts for aboutercent of the total. Various flounders are contribute most among the other species.

Hokkaido, south;

Alaska pollack usually account for about 70 percent and various flounders about 5 percent.

Pacific, north;

Alaska pollack accounts for about 50 percent followed by flounders (10 percent), cods (8 percent) rockfish (3 percent) and squids (6 percent).

Pacific, central and south;

Filefish dominate with about 28 percent, followed by lizardfish (7 percent) and squids (6 percent).

¹ Calculated from the largest catch reported from 1968 to 1977.

² See Figure 1 for the regions.

³ Does not cover the whole of the Japanese coast as the waters along the EastChina Sea coast (west of Kyushu) are not included.

4.2.2 Japan Sea (see Figure 1 for the region)

Hokkaido, west;

The combined catch of Atka mackerel and Alaska pollack accounts for about 88 percent.

Japan Sea, north;

The four major species accounts for about a half of the total catch; these are Atka mackerel (17 percent), Japanese argentine (12 percent), Japanese sandfish (10 percent), and Alaska pollack (10 percent). Various flounders (16 percent), Pacific cod (6 percent), northern shrimp (5 percent), tanner crab (5 percent) and spiny dogfish (4 percent) follow among the rest.

Japan Sea, west;

Squids (17 percent), Japanese roundnose flounder (“mushi-garei”, 14 percent), Sohachi flounder (5 percent) and Japanese argentine (5 percent) are the major species included in the catch. The rest of the catch (about 60 percent) is composed of a variety of species.

4.3 Fisheries and Management

The fisheries harvesting these species are multi-gear fisheries. The gear includes various types of trawl, bottom longlines and gillnets, angling, boat seines, pots, traps and setnets. However, about 70 percent of the total demersal fish catch has been taken by trawls, and the rest (about 30 percent) by a variety of other types of gear. It should also be noted that mechanized trawls have been prohibited entirely in the nearshore waters, as have medium-type offshore trawls in the shallower part of the coastal zone (see Section 2).

The component of the catch taken by trawlers is larger in the north than in the south. It is largest in the waters around Hokkaido, with about 80 percent and decreases toward the south, especially along the Pacific coast. It is down to about 50 percent in the southern region. In the Japan Sea, however, the difference is moderate with about 57 percent in the north and 45 percent in the south. Table 4 shows the figures in more detail.

As discussed previously most of the catch taken from the northern region is composed of a few species of low commercial value, while the catch from the southern region comprises a variety of species of high commercial value although the quantity of each is small compared to the northern species. These facts indicate that the demersal fish species of high commercial value are caught more selectively by various types of small-scale bottom gear rather than by trawls in the southern regions.

In other words, the coastal demersal fisheries around Japan are grouped into two different categories. They are (i) the fisheries aiming at a large quantity of fish of low commercial value, mostly using highly efficient trawls in the northern region and (ii) the fisheries pursuing a small quantity of fish of high commercial value with various kinds of small-scale gear in the southern and western regions. This is a result of the adaptation of the fisheries to natural conditions during a long period of development, i.e. difference in (a) the structure of the fish community, (b) the abundance of stocks and (c) the availability of fish to specific kinds of gear in particular regions.

¹ See Figure 1 for the location of the regions.

² Southernmost prefecture of Kyushu.

³ Prefecture covering the Ryukyu Islands, southwestern-most prefecture of Japan.

⁴ Does not cover the whole of the Japanese coast as the waters along the EastChina Sea coast (west of Kyushu) are not included.

However, it should be noted that fisheries management in Japan has also arranged to support and maintain this adaptation of the fisheries to various local conditions. For instance, licences for the medium-type one-boat offshore trawling, (the minister-licensed fishery, see Section 2 and Table 2), have been granted more often in the northern region than in the south, especially along the Pacific coast.¹ On the other hand, more licences for small-scale trawling, the governor-licensed but nationally registered fishery (see Section 2 and Table 2), have been granted in waters where the prime target species of small trawlers are abundant, e.g. prawns, shrimps, clams, sea cucumbers and various coastal finfish, regardless of the geographic location of the waters. For instance, about 11 300 (43 percent) small trawlers were licensed in the Seto Inland Sea out of the total number of 26 400 vessels licensed for the entire coastal waters around Japan. The case of the Seto Inland Sea will be discussed in further detail in Section 6.

The principle employed in the management of demersal fish fisheries and resources is the same as that for all the fisheries and resources around Japan, namely, the limitation of total fishing intensity as was discussed previously (see Section 2). Generally speaking, the management measures based on an analytical model (e.g. a catch-quota system derived from a yield-per-recruit model) are theoretically applicable to demersal fish stocks. In Japan, however, this type of approach has been little employed because of the extreme difficulties involved in practical application, especially as regards surveillance and enforcement (see Subsection 2.2).

It is often said that the management by control of the total fishing intensity tends to be too late, for conservation and management purposes, to cope with changes in stock abundance. In fact, even in Japan some stocks were depleted by overfishing during the early development of the fisheries in the 1950's and 60's. Both the the catch rate and total catch declined seriously with a large decrease in fish size/age, which resulted in a large loss of net revenue for the fishermen concerned (e.g. some rockfish and flounders in the northern region, red sea bream and bastard halibut in the southern region).

However, some of them had already recovered by the time comprehensive regulatory measures covered the entire region, and others have been recovering in recent years too, although full recovery from the initial decline has taken 10 to 15 years. It should be noted, that the abundance of some stocks that have recovered in recent years far exceeds what it was at the initial stage of the development of the fisheries (e.g. bastard halibut). During the past 15 years, no serious deterioration of stock or drastic change in species composition caused by overfishing has been experienced in the coastal demersal fish resources around Japan. The sequence of events experienced in the Seto Inland Sea will be described in Section 6.

Besides the management scheme employed, a region-specific feature involved in the exploitation of demersal fish resources is that almost the entire distribution range of the fish has been intensively utilized for fishing in some way. As seen in the previous subsection, nearshore waters, where spawning and nursery grounds of many demersal fish species are located, have been utilized intensively by numerous small fishing communities along the coast. This feature of Japanese demersal fish fisheries distinguishes them from trawl fisheries in other advanced fishing countries of the world where the trawlers depend mostly on the offshore distribution of the target species, e.g. the Northwest and Northeast Atlantic Oceans or the Northeast Pacific Ocean.

¹ 258 offshore trawlers (86 percent) were licensed for the waters along the Okhotsk Sea and Pacific coasts of Hokkaido and northern Honshu out of a total number of 301 licensed for the entire Pacific coast of Japan in 1985.

In Japan, therefore, the management of coastal demersal fish resources needs to cover the entire region and a variety of fisheries. A single measure or a simple scheme directed at a specific fishery (e.g. trawl or bottom longline) does not work well. This is one of the reasons why the licensing/ granting scheme in Japan has been so strict in specifying which fisheries may operate in each of the nearshore and offshore zones (see Section 2, Tables 1 and 2). For the same reason, various regulatory measures for conservation purposes have been designed to complement each other and cover the entire distribution range and life cycle of the target resources.

In other words, management of coastal demersal fish resources in Japan has been achieved by a multi-layered structure of regulatory measures applying in different circumstances (i.e. topographic, oceanographic, biological and fisheries conditions). This is another feature that distinguishes these fisheries from demersal fish fisheries in many developing countries, where the entire distribution range of resources has been utilized by various types of fishing gear, as in Japan, but comprehensive management has not yet been applied.

In addition to the legal arrangements made by both the central and local governments, the co-ordination of effort and co-operation between fishermen have undoubtedly contributed to the harmonious utilization of resources and the enforcement of management measures in the demersal fish fisheries (see Sections 2 and 6).