line drawn in a south-southeasterly direction from Nojimazaki in Chiba Prefecture. This sea area is, in turn, subdivided into three smaller units: Sanriku, waters north of 380 north latitude; Tokiwa, 35° north latitude to 380 north latitude; and Nojima, waters to the south of 350 north latitude. The Zunan region lies immediately south of the Tohoku region and has as its western limits 1380 east longitude. The Izu and Bonin Islands, which are included in this division, form sub-regions of their own, being divided at approximately 28°20' east longitude. The Kinan region lies directly off Shikoku and is delineated on the east by 1380 east longitude and on the west by 1310 east longitude. Adjacent to Kinan on the west is the Satsunan region, which includes the northern Ryukyu Islands. In Japan proper, there are a total of 20 or more prefectures which engage in skipjack fishing, most of which border the Pacific Coast. Of these, Miyagi Prefecture is usually the leading producer, followed closely by Shizuoka Prefecture farther to the south. The larger landings of Miyagi Prefecture are due to the strategic location of her ports in relation to the Tohoku area which is conceded to be the most productive of homeland fishing grounds for skipjack. Fishing vessels from Miyagi and nearby prefectures are able to exploit the numerous schools of skipjack which converge in Tohoku waters from July to October chiefly off Cape Kinkazan. Annual catches of these prefectures are therefore relatively higher than those situated elsewhere along the Japanese coast. SEASONS: The Japan Current is assumed to be the controlling factor in the migration of skipjack from southern waters; therefore, it directly affects the yearly fluctuations of the fishery in Japanese waters. This warm-water system originates in the eastern Philippine Islands as a branch of the Equatorial Current. After flowing to the northeast of Formosa and passing through the Ryukyu Islands, the main current of the Japan Current proceeds northeast along the coasts of Kyushu, Shikoku, and Honshu until it reaches the vicinity of Inubozaki in Chiba Prefecture, approximately 370 north latitude. Here the Japan Current meets the Kamchatka Current (Oyashio), a cold current, coming along the coast from the north, and veers east to continue its way across the Pacific. In the spring, with the rise in water temperature and the gradual extension of the Japan Current to the north, migratory skipjack schools start to appear in the Amami-Oshima region, south of Kyushu, in early February. As the season progresses, fishing around the numerous banks in northern Ryukyu waters improves and reaches a maximum in May and June. These banks are relatively shallow with depths of 100 fathoms or less. At this time, fishing vessels from as far as the northern end of Honshu move to southern Kyushu ports to engage in the fishery. The schools continue to proceed north with the Japan Current so that the centers of fishing activity gradually shift from the Satsunan region north to the Kinan and Zunan regions. It is believed that the fish which enter Japanese waters along the Ryukyu chain of islands are joined off eastern Kyushu and Shikoku by skipjack which have migrated from the south along the Kinan reefs. Schools which are abundant in May in the Kinan region are said to decrease markedly in number during the latter part of June, when they presumably join the northward migration. Skipjack from the Zunan region, which first appear near Torishima, are also numerous in May and June, and a part of these schools are said to travel northward in July; the rest remaining in the area until autumn. In July and August, with the Japan Current reaching its maximum development and making its influence felt as far north as the southern Kurile Islands, approximately 46° north latitude, the migrating schools of skipjack converge in an area 150-200 miles east of Kinkazan in Miyagi Prefecture. Since further movement to the north is barred by the presence of the Kamchatka Current with its cold temperatures, the schools remain in the Tohoku area and provide excellent fishing until September. Occasionally, some schools ascend as far north as Etorofu Island, immediately north of Hokkaido. With the gradual decrease in temperature in September, the Japan Current is deflected farther south and is weakened as the cold Kamchatka Current becomes dominant. At this time, the skipjack schools disappear. Where they go and by what routes is still unknown although various views are held on this subject. Some schools are said to have been seen returning southward about 300 miles offshore, presumably to their areas of origin; these schools have been fished. Not a few investigators contend that the skipjack travel due east at greater depths to complete a circular migration to the South Seas, possibly by way of the Hawaiian Islands and Central America. As evidence, they point to the fact that skipjack are often caught by the winter long-line fishery operating 1,500 miles east of Japan and at depths not normally fished for skipjack, approximately 300 feet. However, skipjack taken by these long-lines are usually much larger than those ordinarily caught in Japanese waters. The so-called "resident schools" may be fished throughout the year around the Bonin, Izu, and Ryukyu waters. Fishing operations usually cease during the midwinter months because of unfavorable weather and lack of bait. In addition, "resident skipjack" are not very abundant during the winter, and never furnish the highly productive fishing which is found during the warmer months. SOUTH SEAS: In the former Mandated Islands region, fishing for skipjack was limited for the most part to waters proximate to the widely scattered major fishing bases of Palau, Saipan, Truk, Ponape, and more recently Kusaie and Yap, although it was recognized that there were other potential fishing grounds of importance. Since the fishing boats were of small size, ranging up to 25 and 30 tons, the fishermen usually fished outlying reefs and banks and rarely ventured more than 50 miles from land. Furthermore, trips were limited to a day's duration because it was impossible to keep bait alive for any length of time, not to mention the difficulties of maintaining the quality of fish under prevailing climatic conditions. Weather conditions for fishing are generally ideal throughout the year in the low north latitudes, except from November to February when the northeast trade winds prevail. Although it is possible to catch skipjack during all seasons, fishing usually slacks off in January and February. The period from May to September is reported to provide the best fishing for skipjack. OTHER FISHING GROUNDS: Although the Japanese at one time exploited, skipjack resources of the Indo-Pacific and Philippine regions, detailed information regarding their areas of operation are lacking. However, the general location of fishing grounds in these two regions is presented in "The Japanese Tuna Fisheries" (Shapiro 1948). ACKNOWLEDGMENTS Travel and study in Japan were performed under the auspices of the Supreme Commander for the Allied Powers. The Natural Resources Section under Lt. Col. Hubert G. Schenck, and particularly the Fisheries Division of this Section under William C. Herrington, were largely responsible for the success of the investigation of Japanese tuna research and fishing methods. Dr. K. Kuronuma and S. Takayama of the Central Fisheries Experiment Station in Tokyo, and Dr. Y. Hiyama of Tokyo University were helpful in numerous ways. ESPENSHADE, A. V. 1947. LITERATURE CITED JAPANESE FISHERIES PRODUCTION 1908-46. (A STATISTICAL REPORT), REPORT NO. 95, I MAMURA, YUTAKA 1949. KASK, J. L. 1947. THE JAPANESE SKIPJACK FISHERY. THE TEXT OF THE FISHERY, VOL. 6 (MARCH 5, 1949), JAPANESE FISHING GEAR. REPORT NO. 71, MARCH 5, 1947, SUPREME COMMANDER FOR THE SHAPIRO, SIDNEY 1948. THE JAPANESE TUNA FISHERIES. REPORT NO. 104, MARCH 1948, SUPREME COMMANDER FOR THE ALLIED POWERS, GENERAL HEADQUARTERS, NATURAL RESOURCES SECTION. (ALSO FISHERY LEAFLET 297, APRIL 1948, U. S. FISH AND WILDLIFE SERVICE.) SMITH, R. O. 1947. SURVEY OF THE FISHERIES OF THE FORMER JAPANESE MANDATED ISLANDS. FISHERY LEAFLET That the 1949 United States pack of tuna and tunalike fish, which amounted to 7,290,320 cases (141,700,593 pounds), valued at $97,710,325, was 252,562 cases greater than the 1948 production. However, canners received nearly 15 million dollars less for the pack in 1949 than in the previous year. ANALYTICAL METHODS: The effect of extraction of fish meal with mixtures of water and acetone was investigated with respect to the optimum ratio of ace tone to water. It was found that the greatest amount of ethyl-ether-soluble material was extracted with a mixture of 75 percent acetone and 25 percent water. When the proportion of water was increased or decreased, lesser amounts of ethyl-ether-soluble material was obtained. When the amount of water was increased, a greater amount of total extract was obtained, but the ethyl-ether-purified extract was less than with the 75-25 acetone water solution. PRESERVATION: Samples of the salmon eggs preserved on a large scale during August and September at Ketchikan were examined. It has been found that those samples in which one of the preservative ingredients was sodium chloride are not keeping well. Furthermore, feeding tests carried out at Leavenworth during the past summer indicated that laboratory-preserved samples, in which salt was one of the preservative ingredients, have inferior nutritive value as compared to those samples preserved without salt. FRESH FISH: Another species of rockfish, S. miniatus, (also known as vermilion rockfish) was obtained by the Exploratory Fishing Section's vessel John N. Cobb for a palatability test. Although the skin of this fish has a rather inferior appearance since it is mottled with grayish streaks, the general appearance is quite similar to the red rockfish (S. ruberimis). Because of this mottled appearance, the fishermen have been accustomed to discarding it at sea. In the palatability test carried out on this species it appears that it is just about equivalent to the S. ruberimus in initial palatability. COMPOSITION: Preliminary plans were made for collecting a large number of sam ples of pilchard meal, stickwater, and other products in California for later analysis of Vitamin B,2 and other vitamins by microbiological methods. Several hundred sample bottles were procured and labeled and tentative schedules were drawn up for procuring fish meal at times when it is hoped that the fish-meal plants will be in operation in various California areas. It is planned to procure samples of the raw meal, the semifinished product (cooked fish, press cake, etc.), the final meal and condensed fish solubles in order to determine the effect of processing on destruction of Vitamin B2. It is also planned to obtain from commercial dealers a sufficiently large number of pilchard meals (probably more than 100) in order to determine the range of Vitamin B2 content of this product ordinarily met in commerce. CANNING: Additional samples of gill-net albacore tuna were brought to Seattle by the exploratory vessel John N. Cobb. Some of the samples were iced immediately after catching and then frozen one week later; while others were frozen right after being caught. Final arrangements were made for having these fish, and the others previously obtained, canned at a custom cannery in Astoria. REFRIGERATION: After six months of storage at 0° F., oysters treated with dips and glazes of ascorbic acid and with water only were still considered satisfactory. Although considerable variation had occurred from month to month, due possibly to differences in individual oysters, no one lot receiving a particular treatment had consistently stood out as being superior or inferior. As is generally true with frozen oysters, appreciable quantities of free liquor had formed upon thawing the oysters. A series of frozen whole Dungeness crabs were prepared for a study of the effect of freezing the crabs (cooked and raw) in order to obtain information as to the feasibility of freezing whole crabs aboard a vessel or freezing raw crabs at the production peak in the plant. Melt butter, add crown sugar, seasonings, and pineapple juice, Dip each scallop in the mixture and arrange alternately with pineapple chunks on the skewer. Place skewers across baking dish and bake in hot oven 350° for 30 minutes. Baste twice during cooking. Serve on skewers. Serves 6. A Fish and Wildlife Service tested recipe. This is one in the series of recipes using fishery products tested and developed in the Service's test kitchens. |