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Scallops are the most intensively consumed and fished bivalve mollusks. Over ten scallop species are registered in the seas of the Russian Federation. The most known of them are the Yesso scallop Mizuhopecten yessoensis, which is also well known as Ezo scallop, Giant scallop, Japanese scallop, Russian scallop, Primorsky scallop or Common scallop. For a long time these mollusks have been an object of traditional catching at the coastal waters of the Sea of Japan, Southern Sakhalin, and the Southern Kurile shoal.
Commercial colonies also are known for Chlamys islandica from Barents Sea, Ch. behringiana from Bering Sea, Ch. albida and Ch. chosenica at the Kurile Islands and northern Primorye, and Ch. farreri from Peter the Great Bay and Posjet Bay, Sea of Japan.
We still do not know how ancient people obtained scallops. Without any suitable gear and boats they could probably only collect them from storm debris. The subsequent history of scallop fishing in Primorye is known from descriptions by pioneer explorers of Ussuri Region, including N. M. Przevalsky and V. K. Arseniev. Russian merchants recall that during the last century Yesso scallop was exported as seasoned meat (muscles). Scallops were fished in Vladimir Bay and sold to China. The second half of the 19th century saw further development of scallop fishery along with settlement of the Russian Far East. This was promoted by its value and by the boundless demand on the local market. By the 1920's, the price for Yesso scallop in Vladivostok was as high as 10 rubles per 100 mollusks. By that time, they fished it in shallow bights using one-or-two-pronged lances and scoop nets (while watching it from the surface through a glass-bottom box); primitive dredges and cords (Razin, 1934).
Initially only simplest dredges (about 75 cm wide) were used for scallops fishing. They were towed by small sampans, whose prototypes were brought by members of an expedition led by N. N. Muraviev-Amursky, the first governor-general of Ussuri Territory, together with boats from neighboring countries. Their displacement was 1-1.5 t, and they used either sails or one oar, the so-called "yula". Industrial fishing by means of cords was unique at that time. It was performed in the following way: an anchored buoy was placed in the centre of the catching site, and a cord was attached to it. The cord had length of 200 m and 1-3 mm in diameter. The small lead loads (11-15 g each) were fixed to cord at an interval of every 2 m. The catcher would sail in a boat to drag the cord and start making circles near the buoy. When the cord was trapped by open scallop valves, the mollusk would abruptly close them and affix itself. The more often the catcher would pull the cord, the tighter the bivalve would grip the gear. On even ground, a good catcher would haul several thousand mollusks. In 1919-1920, Yesso scallop in Ussuri Territory was fished by professional women-divers, which had ability to stay underwater for a long time even in cold autumn months. In the end of 1920's, diving gear and motorboats equipped with dredges were introduced. Therefore, greater scallop hauls had been caught in the next decade, when the Association for Exploiting Marine Resources was especially active; this rapidly diminished stocks. After World War II, industrial fishing was resumed for a short while to only be totally banned in 1960.
Yesso scallops and Commercial scallops (Ch. albida, Ch. behringiana and Ch. chosenica) were fished with using small seiners (about 300 tons displacement) at the coasts of northern Primorye, southern Sakhalin, Kurile Islands and Bering Sea. It involves steel dredge, which is 1.5-3.0 m wide with 30-35 cm. The dredge is towed during 5-30 min. In Kuriles, one such haul would yield 0.39-1.28 tons of shells (Kochnev, 1987). In Peter the Great Bay, along the coast by divers apply free diving down to 5 m and SCUBA diving down to 30 m to gather Yesso scallops.
Yesso Scallop landings
Table 6. Annual catch (metric tons) of Yesso scallop in Primorsky Territory in 1919-1937 (by Belogrudov, 1981)
Primorsky Territory. For a long time, Yesso scallop landings in southern Primorye were apparently not recorded. Starting from 1919, when diver boats were introduced, scallop hauls reached the impressive figure of 400 tons. By 1920, industrial fishing grew threefold, but in subsequent years, it sharply declined and then almost stopped. A Trust for Marine Fisheries was organized in 1933 in Vladivostok with a network of enterprises all over the Soviet Far East. The new outfit resumed industrial fishing of the Yesso scallop to raise the average hauls for 1933-1937 up to 900 tons (Table 7). In subsequent years, the scallop was not fished, and only 160 tons were landed in 1948-1949.
Sakhalin-Kurile region. In addition to fishing areas in southern Primorye, Yesso scallop was landed in the Sakhalin-Kurile areas. The commercial fishing of Yesso scallops at Sakhalin and Kurile Islands by Japanese fishers is known from 1930's to 1945. The main fishing area at that time was Aniva Bay. For 1933 to 1943 years, annual yield was within 1'000-2'300 tons. At Southern Kuriles, values for landing were significantly greater (Skalkin, 1966).
Commercial exploitation of scallop population in the Region after World War II was founded by Russian fishers in 1961; scallop was fished only with dredges, from small seiners (Kochnev, 1993). One year later in 1962, catch of mollusks ran up to 5'230 tons. In four years because of excessive catching the annual yields in Aniva Bay were decreased down to 30 tons (Table 7). Although it was quite stable and poorly maintained population of scallops. The commercial stock of this population was evaluated about 3'600 t. The reason of such decrease was obviously dredging method of catch. Therefore, in 1967 catching of scallops in Aniva Bay was banned.
Some years later commercial catching was banned at Southern Kuriles. At Terpenie Bay scallop landing endured only for one year. During a few years the annual yields were inevitably decreased as in Aniva Bay because of excessive and irrational catching (Table 7). In 1976-1984, commercial catching was reinstated, but annual yield was within 9.5-282.9 tons. Since 1985 to present day catching of scallops is banned (Kochnev, 1993).
In 2000 after long-time prohibition, commercial catching using dredging was reinstated again in Aniva Bay (Shpakova, 2001b).
Yesso Scallop Commercial stock
Sakhalin-Kurile region. One can see the found commercial assemblages of Yesso scallop along coast of Sakhalin Island at Aniva and Terpenie Bays on the map (Fig. 9). Commercial stock at Tartar Strait has not been estimated.
(1). In Aniva Bay Yesso scallops are distributed along western, northeastern coasts in total bathymetric range of 8-30 meters. Their distribution has irregular and mosaic pattern. Total stock in Aniva Bay is specified as 16'030 t or 79.37 million specimens and about 4'970 t or 15.63 million specimens of them are commercial stock (Shpakova, 2001a). Average density of settlements at bottom grounds in bathymetric range of 7-21 meters is average up to 4.33 specimens·m-2 at average biomass up to 0.3 kg·m-2. Average shell height of the commercial mollusks (14-99 %) is within 139-156 mm (Shpakova, 2001a, b).
(2). In Terpenie Bay Yesso scallops are distributed along northeastern coast in total bathymetric range of 11-20 meters. Total stock in Terpenie Bay is specified as 1'300 tons or 2.1 million specimens and only about 600 ton of them are commercial stock. Average density of settlements at bottom grounds is average 0.03 specimens·m-2 at average biomass of 0.008 kg·m-2. Average shell height of the commercial mollusks is about 167.1±6.9 mm at individual biomass of 518.7±9.8 grams. Mean age of population is about 6.9 years.
(3). In Kuriles, commercial assemblages of Yesso scallop are known in shallow waters of Kunashir Island and on the South Kuriles Shoal (Fig. 9). Total stock is specified as 40'000 t or 200-300 million specimens; about 18'000 tons of them are commercial stock (Ponurovsky et al., 2000; Ponurovsky and Brykov, 2001). Average density of settlements at bottom grounds in bathymetric range of 5-20 meters is average 0.5 specimens·m-2. Average shell height of the commercial mollusks (44.8 % of total population) is about 126.8±1.1 mm. Mean age of population is about 3.5 years whereas maximum lifetime is12 years.
Commercial Chlamys Scallops
In Primorye Chlamys scallops, mainly Ch. chosenica, form concentrations in total bathymetric range of 25-250 m. V. G. Myasnikov (1982) reported about three large concentrations of Pink scallops along northern coast of Primorye (stretching from Cape Povorotnyj to Cape Zolotoj). The highest density of settlements can reach up to 25 specimens·m-2 at average five specimens·m-2. Total stock of scallops is specified as 420'000 tons or 10.6 million specimens at depth of 90-100 meters. Since 1990, these reserves are providing annually yields of mollusks in the amount of 1000 t (Myasnikov, Hen, 1990).
At Kurile Islands commercial fishing of Chlamys scallops by Japanese fishers is known from 1930's to World War II (Skalkin, 1975). Since 1972, there was renewal of commercial fishing. Until 1975 annual yield did not exceed 140-1'170 t, but since 1976 annual yield increased up to 1'500-3'050 t at average of 1'990 tons. Major scallop landings (about 75 % of annual yield) are derived from the Sea of Okhotsk side of Onekotan Island at depths of 50-200 m (Kochnev, 1987). Now it is the most stable scallop fishery in the Russian Far East region (Myasnikov et al., 1992). Two species of Chlamys scallop (Ch. albida and Ch. chosenica) form mixed settlements. During last years intensity of fishing is increased and provides annual yield within 3'462 - 7'198 t at average 4'693 t (Table 8).Table 8. Annual catch (metric tons) of Chlamys scallops near Onekotan Island (Kurile Islands) in 1976-1997 (by Kochnev, 1993)
The settlements of Chlamys scallops near Onekotan Island are known both at Sea of Okhotsk side and at pacific side of the island. At Sea of Okhotsk side of the island scallops are distributed in total bathymetric range of 40-140 meters. Density of settlements at bottom grounds is up to 90.0 specimens·m-2 at biomass to 6.0 kg·m-2. Average density and biomass is 2.7 specimens·m-2 and 0.25 kg·m-2, accordingly. At pacific side of the island, largest density of settlements was found at the bathymetric range of 40-100 meters. Density of settlements at bottom grounds of this side can run up to 175 specimens·m-2. Total stock of Chlamys scallops in the region is specified as 64'400 t or 730.5 million specimens and about 42'000 t of them is commercial stock.
In Bering Sea commercial concentrations of Bering Sea's scallop Ch. behringiana are known (Myasnikov, 1992). Commercial stock of scallops is specified as 3'000 t in bathymetric range of 110-120 meters.
Other Chlamys Scallops
Chlamys farreri. Japanese scallop Ch. farreri is the most thermophilic scallop in Russian waters and it occurs only in the southern Primorye. One can see the found scallop assemblages on the map (Fig. 6). L. S. Afreichuk (1992b) reported about scallops concentrations in Posjet Bay. Total stock is evaluated at several thousand tons in bathymetric range of 3-5 meters. Commercial stock has not been estimated. This species is object for mariculture and fishery at East Asian countries (Wang, Shieh, 1991). In Russia, mainly in southern Primorye, Japanese scallop is one of most perspective species for fishery and mariculture (Bregman, 1982; Afreichuk, 1992a).
Chlamys swifti. Stocks of Swift scallop Ch. swifti in Primorye has not been estimated. In Aniva Bay, Swift scallop distributed bathymetric range of 2-19 meters. Average density of settlements at bottom grounds changed from 0.04 up to 5.50 specimen·m-2 at average 0.17 specimen·m-2. Biomass changed from 3.8 up to 498.8 g·m-2, but at average not exceeds 16 g·m-2. Shell height is changed within of 32-114 mm at average of 86.8 mm. Individual biomass changed from 24 up to 208 g at average of 94.1 g. Though this species is widespread in the Bay it does not form commercial aggregations because of low density.