@article{oai:kindai.repo.nii.ac.jp:00005109,
 author = {内橋,  潔 and 飯高,  勇之助 and 森永,  勤 and 橘川,  次郎},
 issue = {12},
 journal = {近畿大学農学部紀要, Memoirs of the Faculty of Agriculture of Kinki University},
 month = {Jan},
 note = {[Author abstract]New Zealand is the only country in the world, where the King Salmon has been acclimatised and has become a self-propagating sea-run fish. We visited New Zealand twice (July and November) to gather information on the present status of this fish. From 1864 to 1960 Acclimatisation Societies and the Government of New Zealand introduced salmonid fishes from the northern hemisphere. Consequently, small stocks of the Rainbow Trout, Brown Trout, Sockeye, Atlantic and King Salmon have been established in the South Island of New Zealand. Evidence exists that the King Salmon was established as a sea-run stock as early as 1905-1907, some 70 years ago. The land-locked stock has been discovered since in man-made as well as natural lakes of the Southern Alps System and also in a lagoon on the west coast of the South Island. Their appearance in the lagoon may be due to their sedentary habit (Fig. 9). Among the sea-run stocks most of the populations are confined to the east coast of the South Island, in rivers flowing into Canterbury Bight and Pegasus Bay (Fig. 8). The adults commence their anadromous migration at the beginning of March and continue entering rivers until early May, the height of the run being in March and April (Autumn). They are known to spawn in April and May and their redd, the spawning site, is usually located near a water spring in the upstream (Fig. 13). These fish are usually three or four years old. The lakes in which the King Salmon has been acclimatised and established as a land-locked variety have temperatures ranging from 5.8℃ to 17℃ (Table 3), but mononictic, circulations being caused largely by winds. The availability of suitable habitats in these lakes appears to have contributed to the survival of the King Salmon whose juveniles spend a long period of time in freshwater.The conditions of the east-flowing rivers in which the sea-run salmon spawns are by no means stable, though in the low rain-fall region (Fig. 14) severe flooding occurs occasionally, washing out redds or fry, and changing water courses in the river bed (Fig. 18). These conditions are far from ideal for the self-propagating sea-run fishes.The east coast of the South Island where the sea-run salmon appears is washed by a cold sub-antarctic watermass throughout the year (Fig. 20a and 20b). However, this watermass has greater temperature fluctuations and low salinity, being influenced by the freshwater runoff, than the Southland Current which runs northwards inside the Southland Front offshore. The area in which the sea-run salmon is considered to be confined is thus bordered by the Southland Front to the east and the Sub-tropical Convergence to the north. There is evidence for at least one region, Pegasus Bay, where eddies are formed, affecting the movements of fishes. If the salmon crossed the Southland Front and enter the sub-antarctic surface water the probability is that they would be carried away from the New Zealand coast and would not be able to return. On the other hand, if they were retained in the coastal watermass, either by the eddies or by the front (since they are not known to cross the Subtropical Convergence to enter the sub-tropical surface water), they might return to rivers in this region after a few years in the sea. In fact, older fishes which would normally be found in rivers of their native land (California) have never been recorded in the rivers of New Zealand.We may thus hypothesise that (1) the Southland Current running northwards along the east coast of the South Island has gradients of temperature and salinity across the front which are detected and not crossed by a number of young salmon dispersing in the sea, (2) there are eddies formed within the inshore waters, which retain small salmon in inshore waters, and (3) the King Salmon develops a sedentary habit at a certain age and abandon the pelagic life when they reach a hopefully definable size.Information so far gathered points to the conditions which are consistent with the above hypotheses. It is considered, however, that each is not a sufficient condition to support a natural population of this species in New Zealand. The unstable nature of the river conditions combined with the adaptive responses developed to survive in the sea and to locate the spawning rivers must also be considered.Our deliberations are based on information gathered during our two trips, from various published sources and through discussions with a number of workers in New Zealand, whose names appear in the acknowledgements section of the text.[著者抄録](1)Oncorhynchusの種を北半球から南半球へ移植し、実際に成功した例はNew Zealandがはじめてである。そこで、われわれはこの事実の確認と現情視察のために1977年７、11月の2回、現地を訪れた。(2)New Zealandには1864年以来の努力の結果、Salmonidaeが馴化定着していた。現在、Oncorhynchus nerka (Sockeye salmon), O. tschawytscha (King salmon), Salmo salar (Atlantic salmon), S. trutta (Brown trout) およびS. gairdnerii (Rainbow trout)の定着がみられる。これらの前3種は南島だけに定着し、そのうちSockeye, Atlantic Salmonは陸封型と降海型の2型として馴化している。われわれは特にKing salmonの降海型に興味を持った。この資源量は増大傾向になく平衡状態である。(3)King salmonの馴化定着は1905～7年の間と考えられる。(4)その陸封型は人為的あるいは自然的に生じたもので、現在 Southern Alps系の人工湖、自然湖にみられる｡西海岸の Lagoonにみられる陸封型は種の特性を表わしていると思われる (Fig. 9)。(5)King salmonの降海型は主として東海岸のCanterbury Bright, Pegasus Bayに注ぐ河川に集中している(Fig. 8)｡降海型のそ上期は3月上旬～5月上旬で盛期は3～4月である｡産卵期は4～5月である｡産卵床は河川の上流、湧水のある付近に多くみられる(Fig. 13)。(6)King salmonのそ上年級魚は3～4才が大部分で2才以下はなく、5才以上は珍らしい｡(7)陸封化したKing Salmonの分布する湖は深いが死水がない暖全循環湖である｡年間の水温は5.8～17℃である(Table 3.)。(8)このことはKing Salmonに長期の淡水生活期があることと相まって、最初の移植King Salmonが湖で季節周期性(seasonal periodicity)を変えたためとみられる｡(9)一方、New Zealand南島東部は寡雨(Fig. 14)、ステップ状(Fig. 17)および河川水路が不安定(Fig. 18)で、時々の洪水は産卵床を埋没したり流出するのでKing salmonの自然繁殖に好適とはいえない。(10)また、その沖の海洋は沿岸水Southland CurrentおよびSub-anarctic Surface Waterの支配下で、King Salmonの生息水温、比重をもつ(Table 4.)が、このSub-anarctic Surface Waterは遠く南米のChile沖合まで達している｡この水域に押出されたKing Salmonは環流で押もどされない限り迷い子、逸散魚になる可能性が大きい｡(11)New Zealand南島東海岸沖にはSub-tropical ConvergenceとSouthern Current Frontとで囲まれた水域がある｡この一部にはsalmonの生息によいとみる渦流域もある(Fig. 21)｡この中で生長したKing Salmonが河川にそ上するのであろう。New Zealand King Salmonのそ上がCanterbury Bright, Pegasus Bayに注ぐ河川に集中している処は、Sub-tropical Convergenceの北方への移動によってはPegasus Bay北方の河川にもそ上がみられるは特徴的である。(12)以上はわれわれが検討したNew Zealand King Salmonの概要である｡この資源を増大させ、産業に貢献するためにはKing Salmonの根付性、海洋での行動様式就中Current Frontとの行動学的関係を追求する必要がある。この方面で将来、研究を進めた'いと考えている。, 記念特集II},
 pages = {221--243},
 title = {ニュ-ジランドにおけるマスノスケの馴化定着 : 移殖の経過と現況},
 year = {1979},
 yomi = {ウチハシ, キヨシ and イイタカ, ユウノスケ and モリナガ, ツトム and キッカワ, ジロウ}
}