SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶ᄂᆮ঺ௐऴ‫إ‬

3ᴾ൦ภỆ߼ӫẰủỦἇἃᅹᮄ᫏ỉဃ෇ᴾ῍‫ྶע‬ภଡ଼҄ỉࢨ᪪ửᎋảỦẺỜỆ῍ᴾ
ࡶࡾࡓ

ࡅࢇࡓࢁ࠺

᳃⏣೺ኴ㑻㸦໭ᾏ㐨༊Ỉ⏘◊✲ᡤࡉࡅࡲࡍ㈨※㒊㸧ᡃࠎே㛫ࡣᜏ ື≀࡛࠶ࡾ㸪Ẽ ኚ໬࡟ᑐࡋ࡚య ࢆไᚚࡍࡿࡇ࡜ࡀ࡛ࡁࡲࡍࡀ㸪㨶㢮ࡣኚ ື≀࡛࠶ࡿࡢ࡛㸪࿘ᅖࡢỈ ࡟ᑐᛂࡋ࡚య ࢆไᚚࡍࡿࡇ࡜ࡀ࡛ࡁࡲࡏࢇ㸦ᅗ 1㸧㸬ࡘࡲࡾ㸪᳇ࡳሙᡤࡢỈ ࡟ᛂࡌ࡚య ࡀཷືⓗ࡟Ỵࡲࡿࡓࡵ㸪Ỉࡣ㨶㢮ࡢ⏕άࢆ኱ࡁࡃᕥྑࡋࡲࡍ㸬㨶㢮ࢆ ᗘ໙㓄ࡢ࠶ࡿ⎔ቃୗ࡟࠾ࡃ࡜㸪࠶ࡿỈ ࢆ⬟ືⓗ࡟㑅ᢥࡍࡿࡇ࡜ࡀᐇ㦂ⓗ࡟☜࠿ࡵࡽࢀ࡚࠾ࡾ㸪㨶㢮࡟ࡣ㐺Ỉ ࡀᏑᅾࡍࡿࡇ࡜ࡀศ࠿ࡾࡲࡍ
㸦Golovanov 2013㸧㸬✵㛫ⓗ࡟Ỉ ࡀ୙ᆒ୍࡛࠶
ࡿᾏὒ࡟᳇ࡴᾏỈ㨶࡛ࡣ㸪ᅇ㐟ࡸ㖄┤⛣ື࡟ࡼࡗ࡚⬟ືⓗ࡟Ỉ ࢆ㑅࡭ࡿᶵ఍ࡀከࡃ࠶ࡾࡲࡍ㸬୍᪉㸪㝈ࡽࢀࡓ✵㛫࡟᳇ࡴῐỈ㨶㸦≉࡟ᕝ㨶㸧࡛ࡣ㸪⮬⏤࡟Ỉ ࢆ㑅ࡪࡇ࡜ࡣ㞴ࡋ࠸࡛ࡋࡻ࠺㸬ࡇࡢࡼ࠺࡞⫼ᬒ࠿ࡽ㸪Ỉ ࡀ㨶㢮ࡢ⏕ᜥሙᡤࡢ㑅ᢥࡸᡂ㛗࡞࡝࡟ཬࡰࡍᙳ㡪ࡣ㸪ྂࡃ࠿ࡽ㨶㢮⏕ែᏛࡢ◊✲ࢸ࣮࣐࡜࡞ࡗ࡚ࡁࡲࡋࡓ㸬ᮏ✏࡛ࡣ㸪Ỉ ࡀࢧࢣ⛉㨶㢮࡟ཬࡰࡍᙳ㡪࡟ࡘ࠸࡚➹⪅ࡀ⾜ࡗ࡚ࡁࡓ◊✲ࢆ୰ᚰ࡟⤂௓ࡋࡲࡍ㸬ࡑࡋ࡚㸪㏆ᖺᚰ㓄ࡉࢀࡿᆅ⌫ ᬮ໬ࡀࢧࢣ⛉㨶㢮࡟ࡶࡓࡽࡍᙳ㡪࡟ࡘ࠸࡚⤂௓ࡋࡓ࠸࡜ᛮ࠸ࡲࡍ㸬

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ँภѣཋ

‫٭‬ภѣཋ

‫٭‬ภѣཋ

˳ภℤ൦ภ

˳ภℤ൦ภ

ଡ଼

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ᅗ 㻝䠊㨶㢮䛾య
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㻌

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䛾㛵ಀ䠊㻌

0
20

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ข 40
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8 10 12൦ภΥ⇐∁∞⇪⇕ෙ
ᅸ6⊡11ºC⇿∞∐∙⇖ෙ
ٰ6⊡12ºC⇈∏⇟⇑ฺϤ4⊡8ºCବ4⊡9ºCࢧࢣࡢ⏕ᜥỈ

㹼ࢲ࢖ࢼ࣑ࢵࢡ࡞⛣ື㹼ձ Ỉᖹⓗ࡞⛣ືᮏㄅ࡛ࡶᗘࠎ⤂௓ࡉࢀ࡚࠸ࡲࡍࡀ㸪᪥ᮏ⣔ࡢࢧࢣࡣ໭ኴᖹὒ඲ᇦࢆ኱ࡁࡃᅇ㐟ࡍࡿࡇ࡜ࡀྂࡃ࠿
ࡽ▱ࡽࢀ࡚࠸ࡲࡍ㸦⡿┒ 1975; ᾆ࿴ 2000, ᅗ 2㸧㸬᪥ᮏࡢᕝࢆୗࡗࡓࢧࢣࡢ⛶㨶ࡣ㸪ࡲࡎ࣮࢜࣍ࢶࢡ
ᾏ࡛༙ᖺ࡯࡝ᬽࡽࡋࡓᚋ㸪෤࡟࡞ࡿ࡜༡ୗࡋ࡚໭す໭ኴᖹὒ࡛㉺෤ࡋ㸪⩣ᖺࡢኟ࡟࡞ࡿ࡜໭ୖࡋ࣋
࣮ࣜࣥࢢᾏ࡛㣵ࢆ㣗࡭࡚ᡂ㛗ࡋࡲࡍ㸬2 ᖺ┠௨㝆ࡣ㸪෤࡟࡞ࡿ࡜༡ୗࡋ࡚࢔ࣛࢫ࢝‴࡛㉺෤ࡋ㸪ኟ࡟࡞ࡿ࡜෌ࡧ໭ୖࡋ࡚࣮࣋ࣜࣥࢢᾏ࡛ᬽࡽࡍ⏕ά
ࢆ⧞ࡾ㏉ࡋࡲࡍ㸬ࡲࡓ㸪㏆ᖺࡢ DNA ศᯒ࡜⪥▼ᶆ㆑㨶ࡢ෌ᤕグ㘓࠿ࡽ㸪᫓ࡢ୰す㒊໭ኴᖹὒ࡟ 2ṓ௨ୖࡢ᪥ᮏ⣔ࢧࢣࡀศᕸࡍࡿࡇ࡜ࡀศ࠿ࡾࡲࡋ
ࡓ㸦Sato et al. 2007, 2009㸧㸬ࡇࢀࡣ㸪᫓࡟࢔ࣛࢫ
࢝‴࠿ࡽ⛣ືࡍࡿ㝿㸪୰す㒊໭ኴᖹὒࢆ⤒⏤ࡍࡿ࣮ࣝࢺࡀᏑᅾࡍࡿ࠿㸪࠶ࡿ࠸ࡣ࢔ࣛࢫ࢝‴௨እ࡟ࡶ㉺෤ሙᡤࡀ࠶ࡿࡇ࡜ࢆ♧၀ࡋ࡚࠸ࡲࡍ㸦ᅗ 2㸧㸬࠸ࡎࢀ࡟ࡏࡼ㸪ࡇࡢࡼ࠺࡞ࢲ࢖ࢼ࣑ࢵࢡ࡞⛣ືࡢ࠾࠿ࡆ࡛㸪⏕ᜥሙᡤࡢ⾲㠃Ỉ ࡣᅄᏘࢆ㏻ࡌ࡚ 3㹼12Υࡢ⠊ᅖ࡜Ᏻᐃࡋ࡚࠸ࡲࡍ㸬ࡇࡢࡼ࠺࡞ᾏ࡛

Ϥ3⊡7ºC҅ᙱ҅‫࠯ٽ‬බᅗ 㻞䠊䝃䜿䠄᪥ᮏ⣔䠅䛾ᅇ㐟⤒㊰䛸⏕ᜥỈ㻞㻜㻜㻜 䜢ᨵᅗ䠅䠊㻌


‣࠰Ⴘ
․࠰Ⴘˌᨀ
঺༌ᮄ

䠄⡿┒ 㻝㻥㻣㻡㻧㻌 ᾆ࿴ࡢ⛣ື࡟ࡣไ㝈ࡣ࠶ࡾࡲࡏࢇ㸬ே㛫࡟႘࠼ࡿ࡜㸪ኟࡣ໭ᾏ㐨࡛㸪෤ࡣἈ⦖࡛ᬽࡽࡍࡼ࠺࡞࢖࣓࣮ࢪ
࡛ࡋࡻ࠺㸬ᜏ ື≀ࡢே㛫࡜㐪࠸㸪ኚ ື≀ࡢࢧࢣ࡟࡜ࡗ࡚㸪⏕ᜥỈ 㸦㸻య 㸧ࡣ௦ㅰ⋡࡞࡝ࢆỴࡵࡿ㔜せ࡞せ⣲࡛࠶ࡾ㸪⏕ᜥỈ ࡢᏳᐃ໬ࡣࢧ
ࢣࡢᜏᖖᛶࢆ⥔ᣢࡍࡿୖ࡛Ḟ࠿ࡏࡲࡏࢇ㸬ղ㖄┤ⓗ࡞⛣ື໭ᴟᅪ࡟㏆࠸࣮࣋ࣜࣥࢢᾏ࡜࠸࠼࡝ࡶ㸪ኟሙࡣ⾲㠃Ỉ ࡀ 12Υ㏆ࡃ࡟࡞ࡾࡲࡍ㸬ࡋ࠿ࡋ㸪ᩘ༑࣓࣮ࢺࣝ₯ࡿࡇ࡜࡟ࡼࡾ㸪య ࢆపୗࡉࡏࡿࡇ࡜
ࡀ࡛ࡁࡲࡍ㸬ࢧࢣ࣐ࢫ㢮ࡣᇶᮏⓗ࡟⾲ᒙ࡟ศᕸࡋ
࡚࠾ࡾ㸪Ỉ῝ 40 m ௨῝࡛ࡣ࠶ࡲࡾ⁺⋓ࡉࢀࡲࡏࢇࡀ㸦Morita 2010㸧㸪኱ᆺࡢࢧࢣ࡟㝈ࡗ࡚ࡣỈ῝
30 m ௨῝ࡢ୰ᒙ࡟ࡶศᕸࡋࡲࡍ㸦Morita 2011㸧㸬ኟࡢ࣮࣋ࣜࣥࢢᾏ࡛ࡣ 30㹼40 m ࡯࡝₯ࡿ࡜㸪Ỉ

SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶

ࡀ 5㹼7Υࡃࡽ࠸࡟ࡲ࡛పୗࡋࡲࡍ
㸦ᅗ 2 ᕥୖ㸧㸬ᐇ㝿㸪࣮࣋ࣜࣥࢢᾏࡢࢧࢣࡣỈ῝ 40 m ࡃࡽ࠸ࡲ࡛㢖⦾࡟₯ࡿࡇ࡜ࡀ▱ࡽࢀ࡚࠾ࡾ㸪ࡑࡢ┠ⓗࡣ㣵ࢆ㣗࡭ࡿ࡜࠸࠺ࡇ࡜ࡶゝࢃࢀ࡚࠸ࡲࡍࡀ㸪⤖ᯝⓗ࡟య ࢆⴭࡋࡃపୗࡉࡏ࡚࠸ࡲࡍ㸬ࡇࡢࡼ࠺࡟㸪ࢧࢣࡣỈ ㌍ᒙࢆ㊬ࡄ㖄┤⛣ື࡟ࡼࡗ࡚ࡶయ ࢆㄪ⠇ࡍࡿࡇ࡜ࡀ࡛ࡁࡿࡢ࡛ࡍ㸬ճయࢧ࢖ࢬ౫Ꮡᛶ
ࢧࢣࡀ⏕ᜥࡍࡿỈ ࡣ㸪ᖺ㱋ࡸయࢧ࢖ࢬ࡟ࡼࡗ
࡚ࡶ␗࡞ࡾࡲࡍ㸦ᅗ 3㸪Morita et al. 2010a㸧㸬࣋ࣝࢡ࣐ࣥࡢἲ๎࡜࠸࠺ࡢࢆ⪺࠸ࡓࡇ࡜ࡀ࠶ࡿேࡶ࠸
ࡿ࡜ᛮ࠸ࡲࡍࡀ㸪ࡇࢀࡣ㸪ᐮ෭࡞㧗⦋ᗘ࡟ఫࡴື
≀ࡢ᪉ࡀ㸪 ᬮ࡞ప⦋ᗘ࡟ఫࡴື≀ࡼࡾࡶయࡀ኱
ࡁ࠸࡜࠸࠺⌧㇟࡛ࡍ㸬㨶㢮࡟࠾࠸࡚ࡶ㸪኱ࡁ࠸㨶࡯࡝῝࠸ሙᡤࡸ෭ࡓ࠸Ỉࢆዲࡴࡇ࡜ࡀ▱ࡽࢀ࡚࠾ࡾ㸪ࢧࢣ࡟࠾࠸࡚ࡶ㸪໭࡟⾜ࡃ࡯࡝㸪࠶ࡿ࠸ࡣ῝࠸ሙᡤ࡯࡝㸪⋓ࢀࡿࢧࢣࡢ㨶యࡣᖹᆒⓗ࡟኱ࡁࡃ࡞ࡾࡲࡍ㸦Morita et al. 2010b; Morita 2011㸧㸬2009ᖺࡢኟ㸪ࢧࢣࡢศᕸ໭㝈ࢆ᫂ࡽ࠿࡟ࡍࡿࡓࡵ㸪໭ᴟᾏࡢᒓᾏ࡛࠶ࡿࢳࣗࢡࢳᾏ㸦ᅗ 2㸧ࡲ࡛໭ୖࡋ
ㄪᰝࢆ⾜࠸ࡲࡋࡓ㸦Morita et al. 2009a㸧㸬ࡉࡍࡀ࡟෭ࡓࡍࡂࡿࡓࡵ࠿㸪ࢧࢣࡣഹ࠿ࡋ࠿⋓ࢀࡲࡏࢇ࡛
ࡋࡓࡀ㸪⋓ࢀࡓࢧࢣࡣ኱≀ࡤ࠿ࡾ࡛ࡋࡓ㸦ᅗ 4㸧㸬௨ୖࡣ㔝እ࡛ほᐹࡉࢀࡓ⤖ᯝ࡛ࡍࡀ㸪యࢧ࢖ࢬࡢ
␗࡞ࡿࣈࣛ࢘ࣥࢺࣛ࢘ࢺࢆ ᗘ໙㓄ࡢ࠶ࡿᐇ㦂⎔ቃୗ࡟࠾ࡃ࡜㸪యࢧ࢖ࢬࡢ኱ࡁ࠸ಶయ࡯࡝෭ࡓ࠸Ỉ ࢆ⬟ືⓗ࡟㑅ᢥࡍࡿࡇ࡜ࡀ☜࠿ࡵࡽࢀ࡚࠸ࡲ
ࡍ㸦Elliott and Allonby 2013㸧㸬
࡞ࡐ㸪኱ࡁ࠸ࢧࢣࡣ෭ࡓ࠸ᾏࢆዲࡴࡢ࡛ࡋࡻ࠺
࠿㸽ࡑࢀࡣ㸪኱ᆺࡢࢧࢣࡢ᪉ࡀ㸪ᡂ㛗ࢆ᭱኱໬ࡍࡿỈ ࡀప࠸ࡓࡵ࡛࠶ࡿ࡜⪃࠼࡚࠸ࡲࡍ㸦ᅗ 5,
Morita et al. 2010b㸧㸬໭ᾏ㐨ἢᓊ࡟ศᕸࡍࡿ࣍ࢵࢣ
࡛ࡶఝࡓ⌧㇟ࡀ☜ㄆࡉࢀ࡚࠾ࡾ㸪኱ࡁ࠸࣍ࢵࢣ
㸦>25 cm㸧ࡣỈ ࡀప࠸ᖺ࡯࡝㸪㏫࡟ᑠࡉ࠸࣍ࢵ
ࢣ㸦<25 cm㸧ࡣỈ ࡀ㧗࠸ᖺ࡯࡝㸪ᡂ㛗ࡀⰋ࠸ഴྥ࡟࠶ࡾࡲࡍ㸦Morita et al. 2015a㸧㸬

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10

ἇἃ

ỽἻἧἚἰἋ

1ബ

1ബ

2ബ

8

ෙ൦ภ
(Υ)
㻌

4

3ബ

6

4ബ

4

1ബ

2ബ

ἫἝἈἃ
2

3ബ

20

30

40

50

60

‫ރ‬ӎᧈ (cm)ᅗ 㻟䠊᫓䛾໭す໭ኴᖹὒ䛻䛚䛡䜛䝃䜿䝬䝇㢮䛾ᖺ㱋ู⏕ᜥỈ䠄㻹㼛㼞㼕㼠㼍㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻜㼍䠅䠊㧗㱋䛾኱䛝䛔ಶయ䜋䛹෭䛯䛔ᾏᇦ䛻ศᕸ䛩䜛䠊㻌ᅗ 㻠䠊䝏䝳䜽䝏ᾏ㻔໭⦋ 㻢㻥°㻕䛷ᤕ⋓䛥䜜䛯䝃䜿䠄㻹㼛㼞㼕㼠㼍㻌 㼑㼠㻌 㼍㼘㻚㻌㻞㻜㻜㻥㼍䠅䠊Ἀྜ䜢ᅇ㐟୰䛾䝃䜿䝬䝇㢮䛿ⓙ㖟Ⰽ䛷✀ุู䛜㞴䛧䛔䛜䠈ᑿ㫅䛾ᶍᵝ䛷✀ุู䛷䛝䜛䠄᳃⏣ 㻞㻜㻜㻥䠅䠊㻌
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1.4

ࡀ⏕άྐ࡟ཬࡰࡍᙳ㡪ձᡂ㛗࡜ᡂ⇍⋡ࡢ㛵ಀỈ ࡣࢧࢣ⛉㨶㢮ࡢᛶᡂ⇍࡟┤᥋ⓗ࡟ࡶస⏝ࡋ
ࡲࡍࡀ㸦Morita et al. 2009b㸧㸪ᡂ㛗ࢆ௓ࡋ࡚ᡂ⇍⋡㸦ᅇᖐᖺ㱋㸧࡟ࡼࡾ኱ࡁ࡞ᙳ㡪ࢆཬࡰࡋࡲࡍ㸬ඛ
࡟㏙࡭ࡓࡼ࠺࡟㸪㨶㢮ࡢᡂ㛗࡟ࡣ᭱㐺࡞Ỉ ᖏࡀ࠶ࡾ㸪Ỉ ࡀపࡍࡂࡓࡾ㧗ࡍࡂࡓࡾࡍࡿ࡜㸪ᡂ㛗ࡀᝏ໬ࡋࡲࡍ㸬እὒ࡛ࡢᡂ㛗ࡢⰋࡋᝏࡋࡣ㸪ᡂ⇍᫬㸦ᅇᖐ᫬㸧ࡢయࢧ࢖ࢬ࡟ᙳ㡪ࡍࡿࡔࡅ࡛ࡣ࡞ࡃ㸪ᡂ⇍ࡍࡿࡲ࡛࡟ᚲせ࡞ᖺᩘ࡟ࡶᙳ㡪ࡋࡲࡍ㸬ࡘࡲࡾ㸪እὒ࡛ࡢᡂ㛗ࡀᝏࡃ࡞ࡿ࡜㸪ᑠᆺ໬ࡍࡿࡔࡅ࡛ࡣ࡞ࡃ㸪㧗㱋໬ࡍࡿࡼ࠺࡟ࡶ࡞ࡾࡲࡍ㸬1970 ᖺ௦௨㝆࡟ᵒᵎᶁᶋˌɥỉἇἃᵒᵎᶁᶋச฼ỉἇἃ

1.3

Ꮔ฼ࡇ

Ỉ

1.2
1.1
1.0
0.9

2

3

4

5

6

7

8

㻌

ෙ൦ภ (Υ)ᅗ 㻡䠊᫓䛾໭す໭ኴᖹὒ䛻䛚䛡䜛䝃䜿䛾⏕ᜥỈ 䛸⫧‶ᗘ䛾㛵ಀ䠄㻹㼛㼞㼕㼠㼍㻌 㼑㼠㻌 㼍㼘㻚㻌 㻞㻜㻝㻜㼎䠅䠊▮༳䛿㧗䛔⫧‶ᗘ䛜ほ 䛥䜜䛯ᾏỈ 䛷䠈኱䛝䛔䝃䜿䛾᪉䛜෭䛯䛔ᾏỈ 䛷⫧‶ᗘ䛜᭱኱໬䛥䜜䜛䠊㻌

9

SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶ճἙᕝỈ ࡜ࢧࢡ࣐ࣛࢫࡢ⏕άྐ࡯࡜ࢇ࡝ࡢࢧࢣ࣐ࢫ㢮ࡣ㸪ᕝ࡛⏕ࡲࢀ㸪㝆ᾏࡍࡿࡲ࡛ࡣᕝ࡛㐣ࡈࡋࡲࡍ㸬ᕝ࡛ࡣ㝈ࡽࢀࡓ⏕ᜥ✵㛫ࢆ฼⏝ࡋ࡞ࡅࢀࡤ࡞ࡽࡎ㸪ᇶᮏⓗ࡟ࡣཷືⓗ࡞Ỉ ⎔ቃ࡟ᨭ㓄ࡉࢀࡲࡍ㸬ࢧࢡ࣐ࣛࢫࡣ 1 ᖺ௨ୖࡢἙᕝ⏕άᮇࢆᚲせ࡜ࡍࡿࡓࡵ㸪ἙᕝỈ ࡢᙳ㡪ࢆ≉࡟ཷࡅࡸࡍ࠸ࢧࢣ࣐ࢫ㢮࡜ゝ࠼ࡲࡍ㸬ࢧࢡࣛ

k = 0.30
k = 0.35
k = 0.40
k = 0.45
k = 0.50
k = 0.55

75

঺༌ἇỶἌ
(cm)


ᡮẟ
70

65

᡿ẟ

60
3.0

3.5

4.0

4.5

5.0



࠯‫঺ר‬༌࠰ᱫᅗ 㻢䠊䝃䜿䛾ᖹᆒᡂ⇍ᖺ㱋䠄ᅇᖐᖺ㱋䠅䛸 㻠 ᖺ㨶䛾ᡂ⇍䝃䜲䝈䛾㛵ಀ䠄㻹㼛㼞㼕㼠㼍㻌 㼍㼚㼐㻌 㻲㼡㼗㼡㼣㼍㼗㼍㻌 㻞㻜㻜㻣䠅䠊㟷୸䛿ほ ್䠄㻝㻥㻢㻞㻙㻝㻥㻥㻤 ᖺ⣭䠅䠈ᶳグྕ䛿䝃䜲䝈ᵓᡂ䝰䝕䝹䠄㻹㼛㼞㼕㼠㼍㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻜㻡䠅䛻䜘䜛䝅䝭䝳䝺䞊䝅䝵䞁್䠈㼗 䛿 㼢㼛㼚㻌㻮㼑㼞㼠㼍㼘㼍㼚㼒㼒㼥䛾ᡂ㛗ಀᩘ䠊㻌




1.5

1.5

2008

2008

2007
1.0

1.0

2007



‫ྙׅ࠙‬
(%)


ղỈ ࡜ᅇᖐ⋡ࡢ㛵ಀᗂ⛶㨶ᮇࡢἢᓊỈ ࡜ᅇᖐ⋡㸦⏕Ꮡ⋡㸧࡟┦㛵ࡀ࠶ࡿࡇ࡜ࡣ㸪᪥ᮏࡢࢧࢣࢆྵࡵ࡚㸪ከࡃࡢࢧࢣ
࣐ࢫ㢮࡛ሗ࿌ࡉࢀ࡚࠸ࡲࡍ
㸦Pearcy 1992; Mueter et
al. 2002; Saito and Nagasawa 2009㸧㸬໭⡿ࡢ 120 ಶయ⩌ࢆᑐ㇟࡜ࡋࡓ◊✲࡛ࡣ㸪໭᪉ࡢಶయ⩌࡛ࡣἢᓊỈ ࡀ㧗࠸࡯࡝ᅇᖐ⋡ࡀ㧗ࡲࡿࡀ㸪༡᪉ࡢಶయ
⩌࡛ࡣἢᓊỈ ࡀప࠸࡯࡝ᅇᖐ⋡ࡀ㧗ࡲࡿࡇ࡜ࡀ
ሗ࿌ࡉࢀ࡚࠸ࡲࡍ㸦Mueter et al. 2002㸧㸬ࡇࢀࡽࡢ◊✲ࡣ㸪࠶ࡿ㐺Ỉ ᖏ࡛ᅇᖐ⋡ࡀ㧗ࡲࡿࡇ࡜㸪ࡑࡋ࡚㸪㝆ᾏ┤ᚋࡢἢᓊᇦ࡛኱ࡁ࡞Ṛஸࡀ࠶ࡿࡇ࡜
ࢆ♧၀ࡋ࡚࠸ࡲࡍ㸬࡜ࡇࢁࡀ㏆ᖺࡢ◊✲࡛㸪ᨺὶ┤ᚋ࡟Ἑᕝෆ࡛Ṛஸࡍࡿಶయࡀ┦ᙜᩘ࠶ࡾ㸪ᅇᖐ⋡ࢆᕥྑࡍࡿࡇ࡜ࡀ ศ ࠿ ࡗ ࡚ ࡁ ࡲ ࡋ ࡓ 㸦 Chittenden et al. 2010;
Melnychuk et al. 2014㸧㸬౛࠼ࡤ㸪ࢫࢳ࣮ࣝ࣊ࢵࢻ
ࢺࣛ࢘ࢺ㸦㝆ᾏᆺࢽࢪ࣐ࢫ㸧࡛ࡣ㸪ࢫࣔࣝࢺ໬ࡋ
ࡓಶయࡀ᭱ึࡢࡓࡗࡓ 3 km ࡢ༊㛫ࢆୗࡿ㛫࡟㸪ᨺὶ㨶ࡣ 30㸣㹼40㸣㸪㔝⏕㨶ࡣ 7㸣㹼13㸣ࡢಶయࡀṚஸࡋࡓ࡜ሗ࿌ࡉࢀ࡚࠸ࡲࡍ㸬༓ṓᕝ࡟ᨺὶࡉ
ࢀࡓࢧࢣ࡛ࡣ㸪ᨺὶᮇ㛫୰ࡢἙᕝỈ ࡸ 10 km ୗὶ࡛ࡢ⛶㨶┠どᩘ࡜ᅇᖐ⋡࡟┦㛵ࡀ࠶ࡿࡇ࡜ࡀศ
࠿ࡾࡲࡋࡓ㸦ᅗ 7㸧㸬ࡍ࡞ࢃࡕ㸪ᾏ࡟฿㐩ࡍࡿ๓࡟㸪Ἑᕝෆ࡛ࡶ኱ࡁ࡞ῶ⪖ࡀ࠶ࡿ࡜⪃࠼ࡽࢀࡲࡍ㸦Morita et al. 2015b㸧㸬௒ᚋࡣ㸪ἙᕝỈ ࡜Ἑᕝෆ࡛ࡢṚஸ࡟ࡘ࠸࡚ࡶὀ┠ࡍࡿᚲせࡀ࠶ࡾࡑ࠺࡛ࡍ㸬





2001
0.5

0.0

2001

'06
'04
6

'03
7

2002

0.5

2002
'05

8

9

0.0
0

'05
'03 '06
'04
10000

20000


ඕ߷൦ภ
(Υ)
ᆐᮄႸᙻૠ
ᅗ 㻣䠊༓ṓᕝ䛻䛚䛡䜛䝃䜿ᨺὶ㨶䛾ᖺ⣭ู䛾ᅇᖐ⋡䛸䠐᭶ୗ᪪䠄㝆ୗ䝢䞊䜽᫬ᮇ䠅䛾ἙᕝỈ 䛚䜘䜃༓ṓ䝃䜿䛾䜅䜛䛥䛸㤋䠄ᨺὶᆅⅬ䛾 㻝㻜㻌 㼗㼙 ୗὶ䠅䛻䛚䛡䜛⛶㨶┠どᩘ䛾㛵ಀ䠄㻹㼛㼞㼕㼠㼍㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻡㼎 䜢ᨵኚ䠅䠊㻌ὀ䠖䛣䛣䛷䛾ᅇᖐ⋡䛿Ἑᕝ෌ᤕ⋡䛷䠈ἢᓊ⁺⋓䛥䜜䛯ಶయ䜔Ἑᕝᤕ⋓䛥䜜䛺䛛䛳䛯ಶయ䛿ྵ䜎䜜䛺䛔䠊㻌
㻌
㻌
㻌
㻌

4.0

঺ᧈྙ (% day-1)

࠾ࡁࡓࢧࢣࡢᑠᆺ໬࣭㧗㱋໬ࡣ㸪ᡂ㛗㏿ᗘࡢኚ໬࡟ࡼࡿࡶࡢ࡛࡯ࡰㄝ࡛᫂ࡁࡿࡇ࡜ࡀศ࠿ࡾࡲࡋࡓ㸦Morita et al. 2005, ᅗ 6㸧㸬ࡲࡓ㸪࠶ࡿᖺ࡟ᡂ⇍㸦ᅇᖐ㸧ࡍࡿ࠿࡝࠺࠿ࡢỴᐃ࡟ࡣ㸪๓ᖺࡢᡂ㛗ࡀ᭱ࡶᙉࡃᙳ㡪ࡍࡿࡇ࡜ࡶศ࠿ࡾࡲࡋࡓ㸦Morita andFukuwaka 2006㸧㸬ࡘࡲࡾ㸪࠶ࡿᖺࡢ࣮࣋ࣜࣥࢢᾏࡢỈ ࡀୖ᪼ࡋ㸪ᡂ㛗ࡀᝏ໬ࡍࡿ࡜㸪⩣ᖺ࡟ᡂ⇍㸦ᅇᖐ㸧ࡍࡿࡢࢆࡸࡵ࡚㸪⩣ࠎᖺ࡟ᡂ⇍㸦ᅇᖐ㸧ࡍࡿࡼ࠺࡟࡞ࡿ࡜ண᝿ࡉࢀࡲࡍ㸬ࡓࡔࡋ㸪ᡂ⇍㸦ᅇᖐ㸧ࡍࡿ࠿࡝࠺࠿ࢆỴࡵࡿ㜈್ࢧ࢖ࢬࡣ㑇ఏⓗ࡟Ỵࡲࡗ࡚࠸࡚㸪ࡑࡢ㜈್ࢧ࢖ࢬࡀኚ໬ࡍࡿྍ⬟ᛶࡶ࠶ࡾࡲࡍ㸬ᐇ㝿㸪኱ᆺ㨶ࢆ㑅ᢥⓗ࡟⁺⋓ࡍࡿἈྜὶࡋ⥙⁺ᴗࡀ┒ࢇ࡛࠶ࡗࡓ
1970㹼1980 ᖺ௦ࡣ㜈್ࢧ࢖ࢬࡀᑠᆺ໬ࡋ㸪200 ࢝
࢖ࣜつไ࡟ࡼࡾἈྜ⁺ᴗࡀ⾶㏥ࡋࡓ 1990 ᖺ௦࡟ࡣ㜈್ࢧ࢖ࢬࡀ෌ࡧ኱ᆺ໬ࡍࡿഴྥࡀぢࡽࢀ࡚࠸ࡲࡍ㸦Fukuwaka and Morita 2008; ᳃⏣ 2015㸧㸬

5

ᵎബ

3.0

2.0

1.0

ᵏബ
0.0
12/1 1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/1 11/1 12/1

Ϥ

ବ



ٰ

ᅸ

Ϥ

ᅗ 㻤䠊䝃䜽䝷䝬䝇ᗂ㨶䛾ᡂ㛗⋡䛾Ꮨ⠇ⓗኚ໬䠄㻹㼛㼞㼕㼠㼍㻌 㼑㼠㻌 㼍㼘㻚㻌㻞㻜㻝㻜㼏䠅䠊

SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶
25

2+

ᵐബ

45ºN

20


‫ރ‬ӎᧈ
(cm)

1+

40ºN

ᵏബ
15

ᵎബ
10

10

35ºN

12

14

16

18


ඕ߷൦ภ
(Υ)

ᅗ 㻥䠊᪥ᮏᾏഃ 㻝㻞 Ἑᕝ䛻䛚䛡䜛䝃䜽䝷䝬䝇ᗂ㨶䛾ᖺ㱋ูᑿཫ㛗䛸ἙᕝỈ 䛾㛵ಀ䠄㻹㼛㼞㼕㼠㼍㻌㼍㼚㼐㻌㻺㼍㼓㼍㼟㼍㼣㼍㻌㻞㻜㻝㻜䠅䠊㻌൦ภ (Υ)

15
10

ஜ්

5

ૅ්

0
11/6 12/6 1/6 2/6 3/6 4/6 5/6ᅗ 㻝㻜䠊ᗢ㊰ᕝᨭὶ䠄㻞㻜㻜㻤 ᖺ 㻝 ᭶䠅䠊⾲㠃䛿⤖ị䛧䛶䛔䜛䛜䠈䛣䛾ᨭὶ䛻䝃䜽䝷䝬䝇ᗂ㨶䛜㉺෤㐳ୖ䛧䠈⩣᫓䛣䛾ᨭὶ䛛䜙䝇䝰䝹䝖໬䛧䛶㝆ᾏ䛧䛯䠄㻹㼛㼞㼕㼠㼍㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻝䠅䠊㻌㻌㻌ᅗ 㻝㻝䠊䝃䜽䝷䝬䝇䛾ṧ␃ᆺ㞝䠄ᕥୖ䠅䛸㝆ᾏᆺ㞤䠄ྑ䠅䠊ⓑᴃ෇ෆ䛿䝇䝰䝹䝖໬䛧䛯ಶయ䛷䠈ᾏ䜈ୗ䜛┤๓䛾㝆ᾏᆺ䠊㻌㻌
100സသ‫׹‬ᨺỉЈྵྙ (%)

A

120

100

80

60
10

12

14

16

18

C

60

40

20

5

6

7

ඕ߷൦ภ
(Υ)

60

40

20

100

80

0

B
80

0

20

ඕ߷൦ภ (Υ)

100ᨀෙ‫׹‬ỉࣱൔ (ᨺ%)

࢘ബᮄỉ‫ރ‬ӎᧈ
(cm)࣐ࢫᗂ㨶ࡢᡂ㛗⋡࡜ἙᕝỈ ࡢᏘ⠇ኚ໬ࡣྠㄪࡋ
࡚࠾ࡾ㸪Ỉ ࡀపୗࡍࡿ෤Ꮨ࡟ࡣ඲ࡃᡂ㛗ࡏࡎ㸪Ỉ ࡀୖ᪼ࡍࡿ᫓࠿ࡽኟ࡟࠿ࡅ࡚ᡂ㛗⋡ࡀ㧗ࡲࡾࡲࡍࡀ㸪Ỉ ࡀⴭࡋࡃ㧗࠸ 8 ᭶࡟ࡣᡂ㛗ࡀ㕌ࡃ࡞ࡿഴྥࡶㄆࡵࡽࢀࡲࡍ㸦ᅗ 8㸧㸬ࡲࡓ㸪ࢧࢡ࣐ࣛࢫᗂ㨶ࡢయࢧ࢖ࢬࡣᆅ⌮ⓗኚ␗ࡀ኱ࡁࡃ㸪ἙᕝỈ࡜ṇࡢ┦㛵ࡀ࠶ࡾ㸪㈇ࡢ⦋ᗘࢡࣛ࢖ࣥࢆ♧ࡋࡲࡍ㸦ᅗ 9㸧㸬୍᪉㸪ࢧࢡ࣐ࣛࢫࡢ༸ࢧ࢖ࢬࡣṇࡢ⦋ᗘࢡࣛ࢖ࣥࢆ♧ࡋ㸪⛶㨶ᮇࡢᡂ㛗᮲௳ࢆ⿵ൾࡍ
ࡿࡓࡵࡢ㐺ᛂࡔ࡜⪃࠼ࡽࢀࡲࡍ㸦Morita et al.
2009c㸧㸬
໭ᾏ㐨ࡢἙᕝỈ ࡣ㸪෤Ꮨࡣ 0Υ㏆ࡃࡲ࡛పୗ
ࡋ㸪ኟᏘࡣ 20Υࢆ㉺࠼ࡿࡇ࡜ࡶᑡ࡞ࡃ࠶ࡾࡲࡏ
ࢇ㸬໭ኴᖹὒࢆᅇ㐟ࡍࡿࢧࢣࡀᅄᏘࢆ㏻ࡌ࡚ 3㹼12Υࡢ⠊ᅖ࡟⏕ᜥࡍࡿࡢ࡜ẚ࡭ࡿ࡜㸪ࢧࢡ࣐ࣛࢫ
ᗂ㨶ࡢ⏕ᜥỈ ࡣ┦ᙜ࡟ᗈ⠊ᅖ࡛࠶ࡿ࡜ゝ࠼ࡲࡍ㸬ࡋ࠿ࡋ㸪᭱㏆ࡢ◊✲࡟ࡼࡿ࡜㸪ࢧࢡ࣐ࣛࢫᗂ㨶ࡶᮏὶ࡜ᨭὶࢆ⛣ືࡍࡿࡇ࡜࡟ࡼࡗ࡚㸪⏕ᜥỈ ࢆᏳᐃ໬ࡉࡏࡿ౛ࡀ࠶ࡿࡇ࡜ࡀศ࠿ࡗ࡚ࡁࡲࡋࡓ㸬ᗢ㊰ᕝ࡜㔲㊰ᕝ࡛⾜ࡗࡓ◊✲࡛ࡣ㸪Ỉ ࡀ 0Υ࡟
㏆࡙ࡃ෤ሙ࡟㸪ᮏὶࡼࡾࡶᬮ࠿࠸ᨭὶ࡟ࢧࢡ࣐ࣛ
ࢫᗂ㨶ࡀ㐳ୖࡍࡿࡇ࡜ࡀศ࠿ࡾࡲࡋࡓ㸦Morita etal. 2011; Sahashi and Morita 2014㸧㸬ࡇࢀࡲ࡛ࢧࢡ
࣐ࣛࢫᗂ㨶ࡢ㉺෤ሙᡤࡣୗὶࡢὶࢀࡀ⦆ࡸ࠿࡞ሙ
ᡤ࡜ࡉࢀ࡚ࡁࡲࡋࡓࡀ㸪ୖὶࡢᨭὶ࡬⛣ືࡍࡿሙྜࡶ࠶ࡿࡢ࡛ࡍ㸦ᅗ 10㸧㸬ࡲࡓ㸪ᮒኴᕝ࡛⾜ࢃࢀࡓ◊✲࡛ࡣ㸪Ỉ ࡀୖ᪼ࡍࡿኟሙ࡟㸪ᮏὶࡼࡾࡶ
෭ࡓ࠸ᨭὶ࡟ࢧࢡ࣐ࣛࢫᗂ㨶ࡀ㐳ୖࡍࡿࡇ࡜ࡶሗ
࿌ࡉࢀ࡚࠸ࡲࡍ㸦Terui et al. 2014㸧㸬
ࢧࢡ࣐ࣛࢫࡢ⏕άྐ࡟ࡣ㸪ᾏ࡬ᅇ㐟ࡍࡿ㝆ᾏᆺ࡟ຍ࠼㸪ᕝ୍࡛⏕ࢆ㐣ࡈࡍṧ␃ᆺࡀ࠶ࡾࡲࡍ㸦ᅗ
11㸧㸬㏻ᖖ㸪ṧ␃ᆺ࡟࡞ࡿࡢࡣ㞝ࡀከࡃ㸪㞤ࡢṧ␃ᆺࡣ㠀ᖖ࡟⛥࡛ࡍ㸦᳃⏣ࡽ 2009㸧㸬໭᪥ᮏࢆὶ
ࢀࡿ 13 Ἑᕝ࡛ㄪ࡭ࡓ⤖ᯝ㸪ἙᕝỈ ࡀ㧗ࡃᡂ㛗ࡀⰋ࠸ᕝ࡛ࡣ㸪㞝ࡣᾏ࡬ୗࡽࡎ࡟ṧ␃ᆺ࡜࡞ࡿಶ
యࡀከࡃฟ⌧ࡍࡿࡇ࡜ࡀศ࠿ࡾࡲࡋࡓ
㸦ᅗ 12B㸧㸬ࡑࡢ⤖ᯝ㸪ἙᕝỈ ࡀ㧗࠸ᕝ࡛ࡣ㸪㝆ᾏᆺ࡜࡞ࡿ
ಶయࡢᛶẚࡀ㞤࡟೫ࡾࡲࡋࡓ㸦ᅗ 12D㸧㸬ࡲࡓ㸪㝆ᾏᆺ࡜࡞ࡿሙྜ࡛ࡶ㸪ἙᕝỈ ࡀప࠸ᕝ࡛ࡣ㏻
ᖖࡢ 1 ṓ࡛ࡣ࡞ࡃ 2 ṓ௨ୖ࡛㝆ᾏࡍࡿಶయࡀከࡃ
ฟ⌧ࡍࡿࡇ࡜ࡶศ࠿ࡾࡲࡋࡓ㸦ᅗ 12C㸧㸬
ࡇࡢࡼ࠺࡞ἙᕝỈ ࡜⏕άྐࡢ㛵ಀࢆྲྀࡾධࢀ
ࡓ☜⋡ㄽⓗಶయ⩌ࣔࢹࣝࢆᵓ⠏ࡋ㸪Ỉ ୖ᪼ࡢᙳ㡪ࢆࢩ࣑࣮ࣗࣞࢩࣙࣥࡋࡲࡋࡓ㸬ࡑࡢ⤖ᯝ㸪ἙᕝỈ ࡀୖ᪼ࡍࡿ࡟ᚑ࠸㸪ձṧ␃ᆺ࡜࡞ࡿ㞝ࡢ๭ྜࡀቑ࠼ࡿࡓࡵ⁺ᴗᑐ㇟࡜࡞ࡿ㝆ᾏᆺࢧࢡ࣐ࣛࢫࡢ㈨※㔞ࡀῶࡿ㸪ղ㝆ᾏᖺ㱋ࡀ༢⣧໬ࡍࡿࡓࡵ⎔ቃ☜⋡ᛶࡢᙳ㡪ࢆཷࡅࡸࡍࡃ࡞ࡾ㈨※ኚືࡢᖜࡀቑ
ຍࡍࡿ㸦౛㸸ᴟ➃࡞୙⁺ᖺࡀ⏕ࡌࡿ㸧㸪ࡀண ࡉࢀࡲࡋࡓ㸦Morita et al. 2014㸧㸬

ᨀෙ࠰ᱫᵐബỉлӳ (%)

6

8

9

8

10

12

14

ඕ߷൦ภ (Υ)

D

80

60

40

20

0

4

5

6

7

8

ඕ߷൦ภ (Υ)ᅗ 㻝㻞䠊䝃䜽䝷䝬䝇䛾⏕άྐᙧ㉁䛸ἙᕝỈ 䛾㛵ಀ䠄㻹㼛㼞㼕㼠㼍㻌 㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻠䠅䠊ὀ䠖Ỉ 䛿䛭䜜䛮䜜䛾㡯┠䛷᫬ᮇ䛜␗䛺䜛䠊

SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶

㻌
㻌
㻌

ἅἻἲᾀᴾ
ḘỴἳἰἋỉ‫ׅ‬ᢂḘᴾ

ἅἻἲᾁᴾḘἫὊἼὅἂෙồỉ‫ׅ‬ᢂὉบụḘᴾኟࡢ࣮࣋ࣜࣥࢢᾏ࡟ゼࢀࡿࡢࡣࢧࢣ࣐ࢫࡔࡅ࡛
ࡣ࠶ࡾࡲࡏࢇ㸬⯟ᾏ୰ࡣ㸪ࢩࣕࢳ㸪࢜ࢵࢺࢭ࢖㸪࢖ࢩ࢖ࣝ࢝࡞࡝ࡢᾏ⏘့ங㢮㸪ࢧࢣࡢኳᩛ࡛࠶ࡿ
ࢿࢬ࣑ࢨ࣓㸦ⱥྡࡣ Salmon shark㸧㸪ࢧࢣ࡟ᐤ⏕ࡍࡿࣖࢶ࣓࢘ࢼࢠ㸪㝆ᾏᆺࡢ࢜ࢩࣙࣟࢥ࣐ࡸ࢖ࢺࣚ㸦Morita et al. 2009d,e㸧㸪ወጁ࡞ᐜጼࡢ࣍ࢸ࢖࢘࢜
㸦ᅗ 14㸧࡞࡝ᵝࠎ࡞㨶㢮࡟㐼㐝ࡋࡲࡍ㸬࣍ࢸ࢖࢘࢜㸦ᆅ᪉ྡࢦࢵࢥ㸧ࡣ㸪໭ᾏ㐨ἢᓊ࡟ࡶ⏘༸ࡢࡓࡵ࡟᮶㐟ࡋ㸪ࢦࢵࢥỒࡣ㐨༡ࡢ㒓ᅵᩱ⌮࡜ࡋ࡚᭷ྡ࡛ࡍࡀ㸪ࡑࡢᅇ㐟࣮ࣝࢺࡣⰋࡃศ࠿ࡗ࡚࠸ࡲࡏ
ࢇ㸬㨶࡛ࡣ⛣ືࡢࡇ࡜ࢆ͆ᅇ㐟͇࡜ゝ࠸ࡲࡍࡀ㸪㫽࡛ࡣ͆Ώࡾ͇࡜ゝ࠸ࡲࡍ㸬ኟࡢ࣮࣋ࣜࣥࢢᾏ࡟ࡣ㸪Ⰽࠎ࡞Ώࡾ㫽ࡓࡕ㸪ࢥ࢔࣍࢘ࢻࣜ㸪࢚ࢺࣆࣜ࢝㸪ࢶࣀ࣓ࢻࣜ㸪ࣇ࣐࣓ࣝ࢝ࣔ㸪ࣁࢩ࣎ࢯ࣑ࢬࢼࢠࢻ
ࣜ㸪ࣁ࢖࢖࣑ࣟࢬࢼࢠࢻࣜ࡞࡝ࡀΏࡗ࡚ࡁࡲࡍ㸦ᅗ
15㸧㸬㦫ࡃࡇ࡜࡟㸪ࣁࢩ࣎ࢯ࣑ࢬࢼࢠࢻࣜ࡜ࣁ࢖࢖
࣑ࣟࢬࢼࢠࢻࣜࡣ㸪ኟࡢ࣮࣋ࣜࣥࢢᾏ࡬͆㉺෤͇ࡢࡓࡵ࡟Ώࡗ࡚ࡃࡿࡇ࡜ࡀ࢔࣮࢝࢖ࣂࣝࢱࢢࢆ⏝࠸ࡓ◊✲➼࡛ศ࠿ࡗ࡚࠸ࡲࡍ㸦Shaffer et al. 2006;⥥㈏ 2013㸧㸬ࡇࢀࡽࡣ༡༙⌫ࡢࢱࢫ࣐ࢽ࢔ࡸࢽࣗ
࣮ࢪ࣮ࣛࣥࢻ࿘㎶࡛⣴㣵࣭⦾Ṫࡍࡿࡢ࡛㸪໭༙⌫࡛࠶ࡿ࣮࣋ࣜࣥࢢᾏ࡬ࡢΏࡾࡣ㉺෤࡜࠸࠺ࡇ࡜࡟
࡞ࡿࡢ࡛ࡍ㸬

ᵡᵲᵢἑἂ
20

16ºC

20

15

൦ภ
10

10
9/25

9/30

્්ᾉ᪦К߷

10/5

10/10


‫ط‬Ў
(‰)

30

‫ط‬Ў

൦ภ (Υ)

࢔࣓࣐ࢫࡣࢧࢣ⛉㨶㢮࡛ࡍࡀ㸪⏘༸ᚋࡶṚࡠࡇ࡜࡞ࡃ㸪ᾏ࡜ᕝࢆᩘᖺ࡟ࢃࡓࡾ⾜ࡁ᮶ࡋࡲࡍ㸦᳃⏣࣭᳃⏣ 2007㸧㸬࢔࣓࣐ࢫࡀᕝ࡟㐳ୖࡍࡿ⌮⏤ࡣ㸪⏘༸ࡔࡅ࡜ࡣ㝈ࡽࡎ㸪㉺෤ࡸ㉺ኟ࡞࡝ࡢ⌮⏤ࡶ⪃࠼ࡽࢀ࡚࠸ࡲࡍ㸬㐨ᮾ࡟࠾ࡅࡿ࢔࣓࣐ࢫࡢἙᕝ㐳ୖࡣ 8 ᭶୰᪪࠿ࡽጞࡲࡾࡲࡍࡀ㸪8 ᭶ୖ᪪ࡲ࡛ࡣ
ぶ₻㸦ᐮὶ㸧ࡢᙳ㡪࡛ᾏࡢ᪉ࡀᕝࡼࡾࡶ෭ࡓࡃ㸪8᭶ୗ᪪௨㝆ࡣᾏỈ ࡀୖ᪼ࡍࡿࡓࡵᕝࡢ᪉ࡀᾏࡼ
ࡾࡶ෭ࡓࡃ࡞ࡾࡲࡍ㸬࢔࣮࢝࢖ࣂࣝࢱࢢ*࡟グ㘓ࡉࢀࡓỈ ࡜ሷศࡢࢹ࣮ࢱ࠿ࡽ㸪8 ᭶ୗ᪪௨㝆ࡣᾏὒࡶ฼⏝ࡍࡿࡀỈ ࡢప࠸Ἑᕝ࡟⁫ᅾࡍࡿ᫬㛫ࡢ᪉ࡀ㛗࠸ࡇ࡜ࡀศ࠿ࡾࡲࡋࡓ㸦ᅗ 13㸪Morita et al.
2013㸧㸬࢔࣓࣐ࢫࡣᾏỈ ࡀ 16Υ௨ୖ࡟࡞ࡿ࡜ᾐ
㏱ᅽㄪ⠇⬟ࡀపୗࡍࡿࡓࡵ㸦Takami 1998㸧㸪పỈࡢἙᕝࢆ฼⏝ࡍࡿࡇ࡜࡛య ࢆㄪ⠇ࡋ࡚࠸ࡿྍ
⬟ᛶࡀ࠶ࡾࡲࡍ㸬

7

0
10/15

ϐ਺ᾉᤎែ߷ଐ˄ᅗ 㻝㻟䠊䜰䝯䝬䝇䛻⿦╔䛧䛯䜰䞊䜹䜲䝞䝹䝍䜾䛻グ㘓䛥䜜䛯Ỉ䛸ሷศ䛾ኚ໬䠄㻹㼛㼞㼕㼠㼍㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻟 䜢ᨵኚ䠅䠊㻌㻖䜰䞊䜹䜲䝞䝹䝍䜾䛸䛿䠈Ỉ 䜔Ỉᅽ䠄Ỉ῝䠅䜢グ㘓䛷䛝
䜛䝕䞊䝍グ㘓ᶆ㆑䛾䛣䛸䛷䠈෗┿䛿㟁Ẽఏᑟ⋡䠄ሷศ䠅䜒グ㘓䛷䛝䜛 㻯㼀㻰 䝍䜾䠄䜰䜲䝇䝷䞁䝗㻘㻌㻿㼠㼍㼞㻙㻻㼐㼐㼕 ♫〇䠅䠊㻌
㻌
㻌
㻌
㻌

㻌
ᅗ 㻝㻠䠊ኟ䛾䝧䞊䝸䞁䜾ᾏ䛷ΰ⋓䛥䜜䛯䝩䝔䜲䜴䜸䠄䝂䝑䝁䠅䠊኱ᑠᵝ䚻䛺䝃䜲䝈䛜⏕ᜥ䛩䜛䠊㻌
㻌

ឭϤ
6-9உ

ጛ഻
12-4உ

㻌
ᅗ 㻝㻡䠊ኟ䛾䝧䞊䝸䞁䜾ᾏ䛻⁻䛖䝭䝈䝘䜼䝗䝸⛉㫽㢮䠊ྑୖ䛿ㄗ䛳䛶⥙䛻䛛䛛䛳䛯ಶయ䠊ᴾ







SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶

8ᬮ໬ࡢᙳ㡪
๤ྒ଺஖ίɶ‫͌ځ‬ὸ

9/4

8/25

8/15

ᴾ҅ෙᢊ
ᴾ৸ਵ޽
ᴾ‫޽ࢸ׎‬ᴾỴἝὁฺ
ᴾҤிἇἡἼὅ

8/5

7/26
1990

1995

2000

2005

2010

࠰
ᅗ 㻝㻢䠊䜹䝷䝣䝖䝬䝇䛾᮶㐟᫬ᮇ䛾᥎⛣䠄㻷㼍㼑㼢㻌 㼍㼚㼐㻌 㻾㼛㼙㼍㼟㼑㼚㼗㼛㻌㻞㻜㻜㻣㻧㻌㻷㼍㼑㼢㻌㼑㼠㻌㼍㼘㻚㻌㻞㻜㻜㻣㻧㻌 ᳃⏣䜙 㻞㻜㻝㻠㻕䠊㻌ෙ൦ภ ᵆḥ)ᬮ໬ࡍࡿ࡜⏕≀࡟ࡣࡉࡲࡊࡲ࡞ᙳ㡪ࡀ⏕ࡌࡿ࡜⪃࠼ࡽࢀ࡚࠸ࡲࡍ㸬➨୍࡟ࣇ࢙ࣀࣟࢪ࣮㸦㛤ⰼࡸ⦾Ṫᮇ࡞࡝ࡢᏘ⠇ⓗ࡟࠾ࡇࡿ⮬↛⏺ࡢㅖ⌧㇟㸧ࡀኚ໬ࡍࡿ㸪➨஧࡟✀ࡢศᕸᇦࡀ໭ୖࡍࡿ㸪ࡑࡋ࡚㸪➨୕࡟యࢧ࢖ࢬࡀᑠࡉࡃ࡞ࡿྍ⬟ᛶࡀ࠶ࡿ࡜
ゝࢃࢀ࡚࠸ࡲࡍ㸦Gardner et al. 2011㸧㸬
ࣇ࢙ࣀࣟࢪ࣮࡟ࡘ࠸࡚ࡣ㸪㏆ᖺࢧࢣ࣐ࢫ㢮ࡢ᮶㐟᫬ᮇࡀୡ⏺ⓗ࡟᪩ࡲࡗ࡚࠸ࡿࡇ࡜ࡀሗ࿌ࡉࢀ࡚
࠸ࡲࡍ
㸦Juanes et al. 2004; Kovach et al. 2012, 2013㸧㸬
᪥ᮏ࡛ࡣ࢝ࣛࣇࢺ࣐ࢫ࡛ࡑࡢഴྥࡀ㢧ⴭ࡟⾲ࢀ࡚࠾ࡾ㸦᳃⏣ࡽ 2014㸧㸪ࣟࢩ࢔࡛ሗ࿌ࡉࢀ࡚࠸ࡿ᮶
㐟᫬ᮇࡢ᪩ࡲࡾ࡜ྠㄪࡋ࡚࠸ࡲࡍ㸦ᅗ 16㸧㸬᪥ᮏࡢࢧࢣࡢ㐳ୖ᫬ᮇࡣ㸪໭ᾏ㐨࠿ࡽ༡࡟⾜ࡃ࡜㐜ࡃ࡞ࡿࡀ㸪ࡉࡽ࡟༡࡟㐍ࡴ࡜㏫࡟᪩ࡃ࡞ࡿࡇ࡜ࡀ▱ࡽࢀ࡚࠸ࡲࡍ
㸦⬟ໃ 1970; ᚅ㫽 1978; ᒸᓮ 1982㸧㸬ࡇࡢࡼ࠺࡟㸪 ᬮ໬ࡋࡓࡾ㸪ศᕸ༡㝈ᇦ࡟࡞ࡿ࡜
㐳ୖ᫬ᮇࡀ᪩ࡲࡿ⌮⏤ࡣ㸪⛶㨶ࡀἢᓊỈ ࡢప࠸࡜ࡁ࡟㝆ᾏࡍࡿࡓࡵࡢ㐺ᛂ࡛࠶ࡿ࡜⪃࠼ࡽࢀ࡚࠸
ࡲࡍ㸦ᚅ㫽 1978; ᒸᓮ 1982㸧㸬ࡘࡲࡾ㸪ぶࢧࢣࡣ⮬ศࡢࡓࡵ࡛ࡣ࡞ࡃ㸪Ꮚ౪ࡢࡓࡵ࡟㸦ࢃࡊࢃࡊᬬ
࠸᫬ᮇ࡟㸧᪩ࡃᖐࡗ࡚ࡃࡿ࡜ゝ࠼ࡲࡍ㸬ி㒔ᗓࢆὶࢀࡿ⏤Ⰻᕝ࡛ࡣ㸪ࡩ໬ᨺὶ஦ᴗࡀᐇ᪋ࡉࢀࡿ௨
๓࡟㔝⏕ࢧࢣ࡟㛵ࡍࡿㄪᰝ◊✲ࡀ⾜ࢃࢀ㸪༡㝈ᇦࡢ㔝⏕ࢧࢣࡣ㐳ୖ᫬ᮇࡀ᪩ࡃ㸪ぶࢧࢣࡢ᥋ᓊᮇࡢἢᓊỈ ࡣ 20㹼22Υ࡜࠸࠺㧗Ỉ ࡛࠶ࡿࡇ࡜ࡀ
ሗ࿌ࡉࢀ࡚࠸ࡲࡍ㸦⸨ཎࡽ 1983㸧
㸬ࡓࡔࡋ㸪ὀព
ࡍ࡭ࡁⅬ࡜ࡋ࡚㸪 ᬮ໬࡟క࠺᮶㐟᫬ᮇࡢ᪩ࡲࡾ
ࡣ㐍໬ⓗ࡞ᛂ⟅࡛࠶ࡿ࡜࠸࠺Ⅼ࡛ࡍ㸬ྍረⓗ࡞ᛂ⟅࡜ࡋ࡚ࡣ㸪Ỉ ࡀ㧗ࡅࢀࡤ᮶㐟᫬ᮇࡢ㐜ࢀࢆࡶࡓࡽࡍ࡜⪃࠼ࡽࢀ࡚࠸ࡲࡍ㸬ศᕸᇦࡢኚ໬࡟ࡘ࠸࡚ࡣ㸪㔝እࢹ࣮ࢱ࡟ᇶ࡙ࡃᐇド◊✲ࡣ㝈ࡽࢀ࡚࠸ࡲࡍࡀ㸪⾲㠃Ỉ ࡢࢩ࣑࣮ࣗࣞࢩࣙࣥ࡟ᇶ࡙ࡃண ◊✲ࡀᗄࡘ࠿࡞ࡉࢀ࡚࠸
ࡲࡍ㸦Kishi et al. 2010; Abdul-Aziz et al. 2011㸧㸬ࡑࢀࡽ࡟ࡼࡿ࡜㸪ᆅ⌫ ᬮ໬ࡀ㐍⾜ࡋࡓሙྜ㸪ࢧࢣࡢᾏὒศᕸᇦࡣ඲యⓗ࡟໭ୖࡋ໭ᴟᾏ࡛ศᕸᇦ
ࡀᗈࡀࡿࡇ࡜㸪᪥ᮏ⣔ࢧࢣࡢᅇ㐟࣮ࣝࢺ࡛࠶ࡿ࢜
࣮࣍ࢶࢡᾏࡢ⏕ᜥ⠊ᅖࡀῶᑡࡍࡿࡇ࡜㸪᪥ᮏ⣔ࢧࢣࡢ⣴㣵ᾏᇦ࡛࠶ࡿ࣮࣋ࣜࣥࢢᾏࡢ⎔ቃ཰ᐜຊࡀ
ῶᑡࡍࡿࡇ࡜ࡀண ࡉࢀ࡚࠸ࡲࡍ㸬ࡓࡔࡋ㸪ࢧࢣࡣ㖄┤⛣ື࡟ࡼࡗ࡚࠶ࡿ⛬ᗘࡣయ ࢆୗࡆࡿࡇ࡜
ࡀྍ⬟࡛࠶ࡿࡢ࡛㸦๓㏙㸧㸪⾲㠃Ỉ ࡢኚ໬ࡔࡅ
࡛ࡣࡸࡸཝࡋࡵࡢண ࡟࡞ࡗ࡚࠸ࡿ࠿ࡶ▱ࢀࡲࡏࢇ㸬యࢧ࢖ࢬࡢᑠᆺ໬࡟ࡘ࠸࡚ࡣ㸪᪤࡟ᙳ㡪ࡀ⏕ࡌ࡚࠸ࡿྍ⬟ᛶࡀ࠶ࡾࡲࡍ㸬ඛ࡟㏙࡭ࡓࡼ࠺࡟㸪኱ᆺࡢࢧࢣࡢ᪉ࡀ෭ࡓ࠸Ỉࢆዲࡴࡓࡵ㸪 ᬮ໬ࡣ኱ᆺࡢࢧࢣ࡟ᑐࡋ࡚㈇ࡢᙳ㡪ࢆཬࡰࡍ࡜⪃࠼ࡽࢀࡲࡍ㸬ᐇ㝿㸪1970 ᖺ௦࠿ࡽ࣮࣋ࣜࣥࢢᾏ࡛ᐇ᪋ࡉ
ࢀ࡚ࡁࡓㄪᰝ⤖ᯝࢆぢࡿ࡜㸪40 cm ௨ୖࡢࢧࢣࡢ

8.0

6.0

4.0

1975

1980

1985

1.4


Ꮔ฼ࡇ

ᆅ⌫

1990



1995

2000

2005

2010

ᴾᵒᵎᶁᶋˌɥỉἇἃ
ᴾᵒᵎᶁᶋச฼ỉἇἃ

1.2

1.0
1975

1980

1985

1990

1995

ᅗ 㻝㻣䠊䝧䞊䝸䞁䜾ᾏ䛾䝃䜿䛾⫧‶ᗘ䛸ᾏỈ㼑㼠㻌㼍㼘㻚㻌㻞㻜㻝㻜㼎 䜢ᨵኚ䠅䠊㻌
㻌

2000

2005

2010

䛾᥎⛣䠄㻹㼛㼞㼕㼠㼍㻌⫧‶ᗘࡀഹ࠿࡞ࡀࡽపୗࡋ࡚࠸ࡿഴྥ࡟࠶ࡾ㸪௚せᅉࡢຠᯝ㸦⏕ᜥᐦᗘࡸᖺࡢࢺࣞࣥࢻ㸧ࢆ⪃៖ࡋ࡚ࡶ㸪࣮࣋ࣜࣥࢢᾏࡢỈ ୖ᪼࡜᭷ព࡞ᑐᛂࢆ♧ࡍࡇ࡜ࡀ᫂ࡽ࠿࡜࡞ࡗ࡚࠸ࡲࡍ㸦ᅗ 17㸪Morita etal. 2010b㸧㸬⫧‶ᗘࡣᡂ㛗⋡ࡢᣦᶆ࡜࡞ࡿࡢ࡛㸪Ἀྜࡢࢧࢣࡢ⫧‶ᗘపୗࡣ㸪ᅇᖐࡍࡿࢧࢣࡢᑠᆺ
໬࡟⧅ࡀࡾࡲࡍ㸬࠾ࢃࡾ࡟ᬮ໬ࡀࢧࢣ⛉㨶㢮࡬ཬࡰࡍᙳ㡪ࡣࡲࡔ୙༑ศ
࡟ࡋ࠿ᢕᥱࡉࢀ࡚࠸ࡲࡏࢇ㸬౛࠼ࡤ㸪 ᬮ໬ࡢᙳ㡪ࢆࡶࡗ࡜ࡶ⿕ࡿࡢࡣศᕸ༡㝈ᇦ࡜⪃࠼ࡽࢀࡲࡍ
ࡀ㸪ኴᖹὒഃ༡㝈ࡢ฼᰿ᕝ࡛ࡣ㸪㏆ᖺࢧࢣࡀᛴ⃭࡞ቑຍഴྥ࡟࠶ࡾࡲࡍ
㸦ᩧ⸨ 2013; బࠎᮌ 2013㸧㸬
ᬮ໬࡟క࠺ࢧࢣ㈨※࡬ࡢᙳ㡪ࢆ┘どࡋ㸪ண ࡍࡿࡓࡵࡢࢹ࣮ࢱࢆ඘ᐇࡉࡏࡿࡇ࡜ࡀ኱ษ࡛ࡍ㸬୍᪉㸪ࡇࡢศ㔝ࡢ◊✲ࡣᙳ㡪ホ౯ࡢࡳ࡟↔Ⅼࡀᙜ࡚ࡽࢀࡿഴྥ࡟࠶ࡾࡲࡍࡀ㸪ᙳ㡪ホ౯ࡢࡳ࡛ࡣ㐺ษ࡞ᑐ⟇ࡣᐇ⌧࡛ࡁࡲࡏࢇ㸬௒ᚋࡣ㸪 ᬮ໬ࡀ㐍⾜

SALMON ᝟ሗ No. 9  2015 ᖺ 3 ᭶ࡍࡿࡇ࡜ࢆ᝿ᐃࡋ㸪ண㜵ⓗᑐ⟇ࢆㅮࡌࡿࡓࡵࡢ◊✲ࢆ⾜࠺ᚲせࡀ࠶ࡾࡲࡍ㸬㑇ఏⓗከᵝᛶࢆᏲࡿࡇ࡜ࡣ ᬮ໬ᑐ⟇ࡢ୍ࡘ࡟࡞ࡿ࡛ࡋࡻ࠺㸬ࢧࢣ⛉㨶㢮ࡣ㸪ࡑࢀࡒࢀࡢᕝࡈ࡜㸪ࡉࡽ࡟ࡣ⏘༸ሙࡈ࡜࡟⏕ែࡸ⏕άྐࡀ␗࡞ࡿࡇ࡜
ࡀ࠶ࡾࡲࡍ㸦༦㒊ࡽ 2013; Sahashi and Morita 2013㸧㸬
⎔ቃኚື࡟ᑐࡍࡿ㈨※ኚືࡢᛂ⟅ࡀಶࠎࡢಶయ⩌࡟ࡼࡗ࡚␗࡞ࢀࡤ㸪㑇ఏⓗ࡟ከᵝ࡞ಶయ⩌ࢆᏲࡿࡇ࡜ࡣẼೃኚື࡟ᑐࡍࡿண㜵ⓗᑐ⟇࡜࡞ࡿ࡛ࡋࡻ
࠺㸬ࡲࡓ㸪⮬↛⏘༸ࢆ⾜࠺㔝⏕㨶ࡣ⎔ቃኚ໬࡟ᑐ
ࡍࡿ㐺ᛂຊࡀ㧗࠸࡜࠸࠺ᣦ᦬ࡶ࠶ࡾࡲࡍ㸦ᖐᒣ
2012㸧㸬⛣᳜ᨺὶࡣ⾜ࢃࡎ㸪ࡑࢀࡒࢀࡢᨭὶࡈ࡜
࡟⏘༸ࡍࡿ㔝⏕㨶ࢆಖ඲ࡍࡿ࡜࠸࠺ヨࡳࡣ㸪 ᬮ໬ᑐ⟇ࡢ୍ࡘ࡜࡞ࡿ࠿ࡶ▱ࢀࡲࡏࢇ㸬ㅰ㎡ࡇࡇ࡛⤂௓ࡋࡓ◊✲ࡣ㸪໭ᾏ㐨ᩍ⫱ᗇࠕⱝ➉୸ࠖ㸪Ỉ⏘ᗇࠕ㛤ὒ୸ࠖ㸪໭ᾏ㐨༊Ỉ⏘◊✲ᡤࠕ໭ග୸ࠖ
ࢆ⏝࠸ࡓㄪᰝ࡟ࡼࡗ࡚ᚓࡽࢀࡓࡶࡢ࡛㸪஌⤌ဨࡢ᪉ࠎ࡟ࡣᝰࡋࡳ࡞࠸ࡈ༠ຊࢆ㡬ࡁࡲࡋࡓ㸬ࡲࡓ㸪⚟ⱝ㞞❶Ặ㸪Ọἑ஽Ặ㸪᳃⏣ᬗᏊẶࢆጞࡵ࡜ࡍࡿ
ከࡃࡢ◊✲⪅࡜ඹྠ࡛ᐇ᪋ࡋࡓࡶࡢ࡛ࡍ㸬࡞࠾㸪Ỉ⏘ᗇᅜ㝿㈨※ホ౯➼᥎㐍஦ᴗ࠾ࡼࡧ JSPS ⛉◊㈝ 16780143, 19780155, 22780187, 25450293 ࡢຓᡂࢆཷࡅ࡚ᐇ᪋ࡋࡲࡋࡓ㸬ᘬ⏝ᩥ⊩
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