{"created":"2024-04-22T04:05:03.040887+00:00","id":2002250,"links":{},"metadata":{"_buckets":{"deposit":"3a00e183-5c99-4d16-abbe-5dd192c7d715"},"_deposit":{"created_by":10,"id":"2002250","owners":[10],"pid":{"revision_id":0,"type":"depid","value":"2002250"},"status":"published"},"_oai":{"id":"oai:fra.repo.nii.ac.jp:02002250","sets":["12:14:1716951513399"]},"author_link":[],"control_number":"2002250","item_10002_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1982-11","bibliographicIssueDateType":"Issued"},"bibliographicNumberOfPages":"92","bibliographicPageEnd":"116","bibliographicPageStart":"25","bibliographicVolumeNumber":"19","bibliographic_titles":[{"bibliographic_title":"遠洋水産研究所研究報告","bibliographic_titleLang":"ja"},{"bibliographic_title":"Bulletin, Far Seas Fisheries Research Laboratry","bibliographic_titleLang":"en"}]}]},"item_10002_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Salmonid fishes, which are probably most widely appreciated, consist of the genus Oncorhynchus, Salmo, Salvelinus and Hucho. Although the ecological feature such as the frequency of spawning or anadromy varies among species, they all spawn in freshwater. The species of genus Oncorhynchus have higher commercial value among salmonid fishes and they are made much of as one of the most important fisheries resources in the North Pacific. They spend a greater part of their life history in the ocean before they return to rivers to spawn in freshwater. Their dependence on the freshwater including their feeding is extremely low compared with other salmonid fishes. These ecological characteristics make the biomass of the genus Oncorhynchus large that can not be expected from the life history in freshwater alone. However, the degree of dependence on freshwater varies among the species, and it is considered to be closely related to the population structure and its maintenance. It has received much international recognition that the state of origin of anadromous stocks has the right to manage and possess the resource of anadromous fishes including the genus Oncorhynchus. Accordingly the studies on the distribution and origin of salmon, the locality of populations and the migration route in and out of the territorial waters are called for more than ever. Japan, a state of origin of chum salmon, places great emphasis upon the studies of population structure of chum salmon and fishery biology because of its commercial importance as well as the people's liking for chum salmon. Subsequently, the enhancement program such as hatchery activities and egg transplantations has been put forward with remarkable endeavours. The population structure and its maintenance, and the genetic feature of chum salmon populations which occupy the greater part of the species of genus Oncorhynchus distributed in Japan are examined in the current study which will form a basis for the resource management and the study of artificial propagation and transplantations in future. Morphology and tagging activities have been the major tools for the previous population studies of chum salmon, whereas in recent years the emphasis has been laid on biological genetic methods which offer numerous advantages for population studies. In the current study, population analysis of chum salmon in major distribution area is made to define the population structure and genetic feature of chum salmon as a whole as well as the characteristics and the genetic structure of Japanese chum salmon. The population examined include 11 populations on the Continent of North America, three populations in the U.S.S.R. and 43 river populations in Japan. Genetic data were collected from analysis of 14 enzymes. Genetic variants were identified in 16 loci coding for ten out of the above 14 enzymes. Population analysis was made based on the phenotypic and allelic frequencies of each examined population, the average heterozygosity (H) and genetic distance (D) among the examined populations. The results obtained are summarized as follows. Genetic control of polymorphic loci and average heterozygosity (H)  Four isozyme systems among ten polymorphic systems, namely lactate dehydrogenase (LDH-1), α-glycerophosphate dehydrogenase (α-GDH-2), isocitrate dehydrogenase (IDH-2) and malate dehydrogenase (MDH-B) well characterized the genetic feature of each population. Two alleles are identified for the LDH-1 locus. The presence of two, five and three alleles are also identified for the α-GDH-2, IDH-2 and MDH-B loci, respectively. The average heterozygosity, indicating the genetic variability, was calculated for chum salmon river populations which ranged between 0.0319 and 0.0714. The average heterozygosity of vertebrates ranges between 1% and 15% with the average of about 10%, which indicates that the genetic variability of chum salmon is relatively low. Genetic structure of chum salmon populations on the Continent of North America  Almost all the chum salmon stocks on the Continent of North America are maintained under natural conditions and few transplantations have been made among them. Therefore, examination of the genetic structure of North American populations may provide general insights into the population structure of chum salmon under natural conditions. The examined 11 populations in North America can be divided into the populations in Alaska and those in south of British Columbia based on the similarity of the allelic frequency at the IDH-2 and LDH-1 loci. Strong similarity of allelic frequency was observed among the tributary populations of the Fraser River and between the seasonal runs to the Yukon River. Genetic structure of chum salmon populations in the far east regions of the U.S.S.R.  Almost all the populations of chum salmon in the U.S.S.R. are reproduced under natural conditions. However due to the difficulties in sampling, the subject for the study is confined to an area facing the Okhotsk Sea. The analysis of the collections of the coastal area of the Okhotsk Sea revealed several characteristics in the frequencies of alleles of the populations in the western part of Okhotsk centering around the Amur River and the northeastern part of Okhotsk. Significant differences are observed in the allelic frequency at the IDH-2 locus between the two populations, while both populations share a common unique feature in α-GDH-2 variation. Genetic structure of chum salmon populations in Japan  In Japan, hatcheries are established in most rivers which have chum salmon run and therefore Japanese stocks of chum salmon are largely maintained through hatchery activities. The analysis of 43 river populations revealed geographical gradient of the allelic frequencies at the IDH-2 and LDH-1 loci in Honshu populations. The genetic divergence was observed between the northern and southern populations both on the Pacific coast and the Japan Sea coast of Honshu. The division occurs at middle of Iwate Prefecture on the Pacific coast and at northern part of Niigata Prefecture on the Japan Sea coast. In Hokkaido, on the other hand, the distinct feature by area was not observed in the allelic frequencies of the examined river populations. However, the genetic study on river populations in the eastern part of Hokkaido where there have been few transplantations to date revealed two major clusters of (1) Okhotsk and Nemuro and (2) East of Cape Erimo populations. The presence of chum salmon regional populations  The degree of genetic isolation varies among chum salmon river populations (genetic distance ; D=0.00003-0.00844), while the strong genetic similarity is observed among the tributary populations within a single river system (D̅ = 0.00023) and among the proximal river populations (D̅ = 0.00081). It is presumed that the accumulation of the genetic intermingling for generations led to genetic similarity among river populations within one region. Therefore, it is concluded that several regional populations consisting of adjacent river populations are formed throughout the entire distribution, namely (1) western Alaska, (2) central Alaska, (3) British Columbia and northern Puget Sound, (4) southern Puget Sound, (5) northeastern Okhotsk, (6) western Okhotsk (the Amur River), (7) Hokkaido, (8) the northern and (9) southern part on the Pacific coast of Honshu and (10) the northern and (11) southern part on the Japan Sea coast of Honshu. Each regional population defined from the allelic frequencies has a close relation with the regional population which is assumed from the findings on distribution and migration pattern during the ocean phase. Each chum salmon regional population presumed from the result of the tagging operation and others has its unique distribution and migration pattern in the ocean and they tend to repeat the similar pattern every year with a minor fluctuation. Thus the life history of chum salmon suggests less possibility for intermingling among different regional populations than among the same regional populations. It is considered that the presence of regional population and intermingling within regional population which are indicated by continuity and discontinuity in the allelic frequency of chum salmon river populations are closely related to the above differences during their ocean phase. The genetic structure of chum salmon in the species of genus Oncorhynchus  he characteristics of the genetic structure of chum salmon population can be further defined by comparing it with other species of genus Oncorhynchus. Six species of genus Oncorhynchus can be divided into two groups, namely (1) sea water dependent group (chum and pink salmon) and (2) freshwater dependent group (sockeye, coho, masu and chinook salmon). In general, the precise homing is supported for the species in the second group, which indicates the occurrence of the significant genetic divergence even among populations within a single river system or a limited area. Conversely, pink salmon shows extremely low level of the genetic divergence throughout its entire distribution. Formation of several regional populations having similar frequencies of alleles throughout its distribution makes the population structure of chum salmon distinctive among the species of genus Oncorhynchus. This presumably is a reflection of a close relation with the length of the freshwater phase or the degree of precision of the homing. The effects of transplantation in chum salmon  Rivers in Japan have been heavily planted in connection with artificial propagation. However, the effects of transplantation have not been precisely evaluated and opinions are still divided. It is confirmed through this study that the original allelic frequencies remain in the transplanted Tokachi River populations for over three generations which proves the success of the transplantations to the Tokachi River in Hokkaido. However judgning from the change in seasonal distribution of spawning run, transplantations hardly succeed in many rivers. Although many rivers in Honshu have been frequently transplanted from the rivers in Iwate, Yamagata and Hokkaido, each regional population still share a common feature in the frequencies of alleles. This raises a doubt on the effectiveness of the past transplantations. Considering distinct characteristics of each regional population such as the time of return and seaward migration of fry, it is nearly impossible to expect a good result from transplantations from latitudinally distant rivers.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"サケ科魚類は,サケ属(Oncorhynchus),ニジマス属(Salmo),イワナ属(Salvelinus),イトウ属(Hucho)から構成されており,これらは降海性や産卵回数などの生態的特性に様々なちがいがあるが,共通して河川や湖沼で産卵する。このうちサケ属の各種は,産業的に高い価値をもち,北太平洋域での最も重要な魚類資源として国際的に重視されている。サケ属は生活史の過半を海洋で過した後,溯河川で産卵するが,餌料をもふくめて淡水域への依存度が他のサケ科魚類に比べてはるかに低い。このような生態的特性により,サケ属各種は淡水域のみの生活では期待できない生物量をもっているが,淡水域依存性はサケ属各種の間でも異なり,これが各種の集団構造や維持にも大きくかかわっていると考えられる。典型的溯河性魚類であるサケ属の資源の帰属と管理権は母川国にあるとする国際的認識が一層明確になり,これに関連して領海内外でのサケの分布と帰厲,集団の局地性,回遊路の研究が一層厳しく要求されている。サケ(O.keta)の母川国である日本では,国民の嗜好と産業的重要性もあいまって,この魚種の集団研究と資源生物学的研究がますます重要となり,また人工ふ化放流と稚魚の移植による資源増大策が従来にも増して大きな努力で進められている。本研究は我が国のサケ属魚類資源の過半を占めるサケを対象とし,資源管理と今後におけるふ化放流と移植の研究の基礎として,集団の構成と維持,各集団の遺伝的特性について研究したものである。ここでいう集団とは,従来一般にはいわゆる系統群あるいは系群と呼ばれてきたものである。サケの系統群研究は,これまでは主に形態学的に,あるいは標識放流法によって数多く研究されている。本研究では,北米大陸の11河川系,ソ連の3地方および日本の43河川の集団を材料にして,この種の主要分布域をカバーして集団分析を行ない,集団構成と集団遺伝学的特性,そのなかにおける日本の河川にそ上するサケ集団とその特徴および構成を明確にした。遺伝学的研究のために分析した酵素は14種類,そのうち集団分析に利用した多型的酵素と遺伝子座はそれぞれ10種類および16種類である。集団の分折は,各河川集団サンプルにおける表現型度数,遺伝子度数,集団間の遺伝的距離(D),平均へテロ接合体率(H)の検討によって行なった。その結果,得られた主要な知見を要約すれば下記の通りである。遺伝的多型と遺伝的支配および平均へテロ接合体率  多型が見出された10酵素のうち,特に乳酸脱水素酵素(LDH-1), α-グリセロリン酸脱水素酵素(α-GDH-2),イソクエン酸脱水素酵素(IDH-2)およびリンゴ酸脱水素酵素(MDH-B)の4つのアイソザイム系が,サケ各集団の遺伝的組成を良く特徴づけていた。4量体の酵素である LDH-1 では関与している2つの対立遺伝子が,また2量体であるα-GDH-2, IDH-2 およびMDH-Bに関与している各遺伝子座にはそれぞれ2, 5, 3の対立遺伝子が認められた。一方, 22~28遺伝子座について変異性を示す平均へテロ接合体率を求めた結果,サケ河川分集団では0.0319~0.0714 を得た。この値は他の脊椎動物で求められた値と比較してやや低めであり,サケの変異性はそれ程高くないということになる。アメリカ大陸における河川分集団の遺伝的組成  北米大陸の各河川では,本種の大部分は天然条件下で維持されており,河川間での移植等の人為的な影響も無視することができるため,天然状態におけるサケ河川分集団の構造を研究するうえで格好な素材を提供している。検討した11河川系の集団は IDH-2, LDH-1 等の遺伝子組成の類似性で,アラスカとブリティシュ·コロンビア(B.C.)州以南に大別できた。また,フレーザー河の支流分集団間,ユーコン河のそ上時期が異なる2つの分集団間で共に,遺伝子組成に極めて高い近似性が認められた。ソ連極東地区河川分集団の遺伝的組成  ソ連のサケも,その大部分は天然条件下で再生産されているが,種々の制約のため本研究ではオホーツク海に面する地域のみをその対象とした。オホーツク海沿岸からの漁獲物を用いて分析した結果,オホーツク海の西岸(アムール)地方とその他のオホーツク海沿岸地域を起源とする集団の遺伝的特徴が明らかになった。両集団では,IDH-2 等の遺伝子組成に相異が認められた反面, α-GDH-2 に関しては共通して他の地域とは大きく異なる遺伝子組成をもっていた。北海道·本州北部河川分集団の遺伝的組成  我が国では,サケがそ上するほぼすべての河川にふ化場が設置されており,資源の大部分が人工ふ化放流によって維持されている。43河川分集団について分析した結果,本州ではIDH-2とLDH-1 の遺伝子組成に地理的な勾配があり,太平洋側では岩手県中部を,また日本海側では新潟県北部を境にした南北の集団間で,その遺伝的組成に分化があることが明らかになった。一方,北海道内では遺伝子組成に地域による明瞭な差は認められないものの,他河川からの移植が比較的少なかった道東方面に限れば,根室半島を境にしてオホーツク·根室海区と襟裳以東海区の河川分集団間に特徴的な遺伝的差異が認められた。サケ地方集団の存在 このように, サケの各河川分集団は 遺伝的に様々な程度(遺伝的距離:D=0.00003~0.00844)に独立しているが,同一河川内の支流分集団間(D̅ = 0.00023)や地理的に近接した集団間(D̅ = 0.00081)にも遺伝的に高い共通性が認められた。これらの河川分集団間では,ある程度の遺伝的混合が毎世代蓄積された結果,共通の遺伝的組成を持つに至ったと考えた。そして,地理的に近接した機つかの河川分集団からなる地方集団が,西部アラスカ,中央アラスカ,ピュジェット·サウンド北部を含むB.C.州,ピュジェット·サウンド南部,オホーツク海北東部,同西部(アムール),本州太平洋側北部,同南部,本州日本海側北部,同南部および北海道の各地域で形成されていると結論した。また,遺伝的な特徴からみたこれらの地方集団と,サケの海洋生活期における分布·回遊パターンから推定されている地方集団との間には,密接な関連が認められた。海洋生活期中のサケは,一定の地域内の河川にそ上する集団ごとに毎年段ぼ決まった水域を回遊することが,標識放流試験によって明らかにされてきた。しかも,この回遊パターンは地方集団ごとに異なっているため,地方集団間では地方集団内に比べて海洋中で混合を生じる可能性はより少ないものとみられる。サケ河川分集団の遺伝的組成にみられる連続性と不連続性で示される地方集団の存在と地方集団内での混合は,このような海洋における回遊経路のちがい等とも密接に関係していると考えた。サケ属魚類におけるサケ集団の遺伝的特性  サケ集団にみられるこの遺伝的構造は,他のサケ属魚類と比較することによって,その特徴をさらに明確にすることができる。サケ属の6魚種については,発生初期の生活史の特徴から海洋依存型(サケおよびカラフトマス(O.gorbuscha))と淡水依存型(ベニザケ(O. nerka),ギンザケ(O. kisutch),マスノスケ(O.tshawytscha)およびサクラマス(O.masou))の2つのグループに分けられ,一般に後者は母川への厳密な回帰性が支持されており,一水系内あるいは小地城内の分集団間にも極めて高い遺伝的分化が認められている。これに対して,カラフトマスは広い分布域全体を通じても,遺伝的な分化は極めて小さいという特徴を持つ。分布域を通じて遺伝的に特徴のある幾つかの地方集団から構成されているサケの集団構造は,サケ属の中でも特徴的であり,淡水生活期間の長短や母川への回帰性の程度等と密接に関連した結果であると考えた。サケの移植効果  我が国の大部分の河川では,他河川からの移植を経験しているが,移植群のその後の動向については必ずしも明らかではなく,その実際の効果についても様々な議論がある。北海道の十勝川では,本研究を通じて移植後3世代を経ても移植群はなお従来の遺伝的組成を保持しているのが認められ,移植群の十勝川への定着が確認された。しかし,他の多くの河川では移植後のそ上数曲線に現われる変化からみる限り,移植群の定着を示咬する例は少ない。特に,本州では山形県,岩手県あるいは北海道の諸河川から極めて頻繁に移植が行なわれてきたにもかかわらず,なお各地方集団には共通する遺伝的な特徴が認められていることからみても,移植の実際の効果はなお明らかでない。地域ごとに異なるそ上時期や稚魚の降海時期等他の生物的特性を考慮に入れると,南北に距離を隔てた河川からの移植効果は高くないとも考えられた。集団構造に関する知見の蓄積と遺伝的な指標を利用することによって,今後は効果的な移植方法の確立や移植効果の的確な判定が可能になるものと考えられた。","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_10002_publisher_8":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"遠洋水産研究所","subitem_publisher_language":"ja"},{"subitem_publisher":"Far Seas Fisheries Research Laboratry","subitem_publisher_language":"en"}]},"item_10002_relation_16":{"attribute_name":"情報源","attribute_value_mlt":[{"subitem_relation_type_id":{"subitem_relation_type_id_text":"enyo_k_19-25","subitem_relation_type_select":"Local"}}]},"item_10002_relation_17":{"attribute_name":"関連サイト","attribute_value_mlt":[{"subitem_relation_name":[{"subitem_relation_name_text":"日本農学文献記事索引 （AgriKnowledge）"}],"subitem_relation_type_id":{"subitem_relation_type_id_text":"https://agriknowledge.affrc.go.jp/RN/2010270548","subitem_relation_type_select":"URI"}}]},"item_10002_source_id_11":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AN00025949","subitem_source_identifier_type":"NCID"}]},"item_10002_source_id_9":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"0386-7285","subitem_source_identifier_type":"PISSN"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"metadata only access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_14cb"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"岡崎, 登志夫","creatorNameLang":"ja"},{"creatorName":"オカザキ, トシオ","creatorNameLang":"ja-Kana"},{"creatorName":"Okazaki, Toshio","creatorNameLang":"en"}],"familyNames":[{"familyName":"岡崎","familyNameLang":"ja"},{"familyName":"オカザキ","familyNameLang":"ja-Kana"},{"familyName":"Okazaki","familyNameLang":"en"}],"givenNames":[{"givenName":"登志夫","givenNameLang":"ja"},{"givenName":"トシオ","givenNameLang":"ja-Kana"},{"givenName":"Toshio","givenNameLang":"en"}]}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"サケ(Oncorhynchus keta)の集団構造に関する遺伝学的研究","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"サケ(Oncorhynchus keta)の集団構造に関する遺伝学的研究","subitem_title_language":"ja"},{"subitem_title":"Genetic Study on Population Structure in Chum Salmon (Oncorhynchus keta)","subitem_title_language":"en"}]},"item_type_id":"10002","owner":"10","path":["1716951513399"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2024-04-22"},"publish_date":"2024-04-22","publish_status":"0","recid":"2002250","relation_version_is_last":true,"title":["サケ(Oncorhynchus keta)の集団構造に関する遺伝学的研究"],"weko_creator_id":"10","weko_shared_id":-1},"updated":"2025-11-11T02:41:38.937313+00:00"}