シャドーイング練習: Two Different Things Are Killing Sharks - 動画で英語スピーキングを学ぶ

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People tend to think of sharks as fearsome, powerful, untouchable predators.

They're definitely scary and powerful, but… untouchable?

Maybe not as much as you might imagine.

Even the white shark, often considered the largest predatory fish on the planet, is not immune to the unforgiving nature of, well, nature.

These iconic predators of the sea face all kinds of threats.

And in two different places, for two apparently different reasons, great whites are dying in large numbers.

And scientists aren't totally sure why.

First, let's introduce the Great White Shark, also known as the White Pointer, or just simply the White Shark.

They were named for their white undersides, despite the fact that most of the shark is actually gray.

White sharks are common in popular media.

And why wouldn't they be?

They grow to around 4 .5 meters long and roughly 1 ,800 kilograms.

And who doesn't love a massive predator?

They also make pretty compelling subjects for lots of scientific research, and they can be easier to study than other sharks.

See, studying migratory species is extremely hard.

They spend time far offshore and in deep waters that are really hard to reach.

But even though white sharks are also migratory, their patterns can be pretty predictable,

and they tend to spend a lot of their time close to beaches and in shallower waters when they're not crossing oceans.

Bad news if you're a seal.

But if you're a researcher, this makes your job way easier.

And the truth is, sharks, including the white shark, are critical to the health of our ocean ecosystems.

They help regulate the population sizes and behaviors of animals at lower trophic levels, such as sea lions and otters.

So if we want a healthy ocean, and therefore a healthy planet, we want healthy sharks.

Which is where our problem lies.

Let's start with South Africa.

White sharks are ubiquitous in South African waters, aggregating in several regions around the coast.

Or, at least, they used to be.

Over the past decade, people have seen fewer white sharks swimming in those waters, and more of them washing up on beaches.

Beached shark carcasses were often found with missing livers and perfect slashes on them, so precise and clean they almost seemed surgical.

Which probably raised more questions than it answered.

And some people were worried that swordfish had evolved into scalpel fish.

But the discovery of tooth marks on the bodies led scientists to a more feasible hypothesis — orcas.

Although we often describe white sharks as if they're the top of the food chain, that's not always the case.

Orcas are known to hunt white sharks, and they're not interested in a filet -o -shark.

They really just want the shark's liver.

Shark livers are massive, making up approximately a third of their body weight.

They're filled with lipids, and since sharks don't have gas -filled swim bladders like their bony fish cousins,

this fatty liver is what they rely on for buoyancy regulation.

Because of how fatty and nutrient -dense shark livers are, it's the perfect meal for a fast -paced, warm -blooded predator like the killer whale.

Orcas have been known to hunt white sharks in other regions, like California.

And when an orca pod rolls through, the sharks start to roll out, avoiding their predators like any sensible prey would.

However, while the new snacking habits of South African orcas sounds like a tidy answer,

it may not be the only reason the number of white sharks has dipped in the last few years.

In addition to orca gains, South African white sharks are also dealing with fishing pressure and shark deterrent efforts on local beaches.

While experts really aren't sure which factor tipped the shark scales, it all adds up to a pretty hostile environment.

Experts hope that addressing as many of these concerns as possible may bring back the iconic

South African sharks.

Not sure how they'll convince the orcas to lay off the liver, but we'll see what happens.

Our next group of endangered white sharks is found off the coast of North America.

And what's disrupting the sharks in Canada and the US is even more confusing

and less visible than it is in South Africa.

Allow me to explain.

In 2023, a dead white shark washed ashore on Prince Edward Island in Canada.

It didn't look injured and seemed otherwise pretty healthy.

But when researchers did a necropsy, which is just an animal autopsy, they found that the shark had inflammation of the brain and surrounding tissues,

otherwise known as meningoencephalitis.

Meanwhile, more seemingly healthy sharks were washing up dead, blood, many with brain swelling.

One shark was seen displaying some odd behavior, like swimming erratically and bumping into things before dying and washing onto a beach.

Surely this was another case of brain inflammation, right?

Shockingly, no. Just when we think we've figured out a pattern, good ol' Mother Nature throws a curveball.

And it's not just the Great Whites.

Dead sharks with swollen brains seemed to be on the rise in several species, like sandbar sharks and thresher sharks.

Even stranger, this is happening in the Atlantic and the Pacific, meaning whatever the problem is, it's really widespread.

So, some mysterious thing is causing sharks' brains to swell up and die, and we still don't know exactly what.

But, as it turns out, the answer may be hidden in a bunch of decades -old frozen salmon sharks.

In the early 2000s, 18 beached salmon sharks were found to have died of meningoencephalitis.

And in 2012, researchers analyzed some of them and found that a type of bacterium called

Carnobacterium malta rheumaticum was the likeliest culprit.

Which was weird, because this bacterium has been found in other fish species and in the water they swim in.

And those guys all have perfectly unswollen brains.

But for some unknown reason, this bacterium may be becoming pathogenic in some fish, including sharks.

And we have an idea of how it could be reaching their brains.

Through the endolymphatic system, which aids in hearing, balance, and orientation.

Sharks have small pores on their heads that lead to their endolymphatic ducts, which provide access to the cranium.

And we know that when these structures get invaded by pathogens in the water,

it can cause disease and even death in several shark and ray species.

So what do we know?

We know that, for a decade, sharks have been washing up on beaches.

We know that their deaths are often caused or accompanied by meningoencephalitis.

And we know that this disease is sometimes attributed to a particular bacterium.

What we don't know is probably the biggest piece of this medically mysterious marine puzzle,

which is why this is happening and how concerned we all should be about it.

Scientists are worried for some reasons and not so worried for others.

Seeing sharks wash up on shore doesn't seem like it could be positive in any way,

but it could be a sign that shark populations are recovering.

A bigger population of sharks that are living also means there's a bigger population of sharks that are dying, hence an increase in washed up carcasses.

And if this thing is contagious, more sharks also means more of a chance for diseases to be passed around,

simply because the population is bigger and might be more densely packed into an area.

So while we don't love a disease, if it means that shark populations are rebounding, it's not all bad.

The concern comes in though

when we start to think about a bacteria that's been living on other fish species without a problem, suddenly becoming a deadly pathogen in sharks.

If this truly is what is happening, we need to understand why.

Is it climate change?

Pollution?

Or a secret third option?

Knowing what causes the bacterium to go rogue can help us figure out how to stop it from spreading

and prevent it from happening with other bacteria in the future.

These two shark -killing mysteries have two different causes, and therefore two different solutions, at least.

But that also means they're teaching us two different lessons about our planet, our oceans, and all the big and not so big creatures in them,

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from the sharks and the orcas down to tiny bacteria.

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And maybe the biggest one is that the driving force behind ecosystem shifts is never really black and white.

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このレッスンの語彙とスピーキングのポイント

このスピーキングレッスンは、動画「Two Different Things Are Killing Sharks」を教材にしています。繰り返し出てくる語は次のとおりです：shark, orca, brain, liver, fish。この動画には、シャドーイング用の文が101文、単語が1404語あります。音声の長さは7:32です。話す速さは速く、1分あたり約186語です。音のつながりや弱く発音される音が多くなります。英語の頻出3,000語に含まれる単語は77%だけなので、語彙は難しめです。

この動画の重要語彙

動画に出てくる覚えておきたい単語15語を、発音と意味つきで紹介します。

単語	発音	意味
wash 動詞	/wɑʃ/	洗う
predator 名詞	/ˈpɹɛd.ə.tɚ/	天敵
swim 動詞	/swɪm/	泳ぐ
scientist 名詞	/ˈsaɪəntəst/	科学者
liver 名詞	/ˈlɪvɚ/	肝臓, 肝
researcher 名詞	/ˈɹiˌsɝ.t͡ʃɚ/	研究員, 研究者
swell 動詞	/swɛl/	膨れる, 隆起する
mysterious 形容詞	/mɪˈstɪɹi.əs/	神秘的な, ミステリアスな
ecosystem 名詞	/ˈikoʊˌsɪstəm/	生態系
inflammation 名詞	/ɪnfləˈmeɪ̯ʃən/	炎症
meal 名詞	/ˈmiːl/	食事, めし
meanwhile 副詞	/ˈmiːnwaɪl/	その間に
killer 名詞	/ˈkɪlɚ/	殺人者, キラー
lesson 名詞	/ˈlɛs.ən/	授業, 学科
discovery 名詞	/dɪˈskʌv.ɹi/	発見

動画に出てくる句動詞

単語	意味
wash up 動詞	洗面する, 手を洗う
lay off 動詞	解雇する

この動画の文法

話し手がよく使っている文型を、動画の実際の表現とともに紹介します。

文型	動画での表現
現在完了進行形 have/has been + -ing — 以前に始まり今も続いている動作	have been washing · that's been living
受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる	were named · were often found · are known
現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している	have seen · have been known · has dipped

注意したい発音

話し手はthey're, don't, aren'tなど、短縮形や弱形を21回使っています。聞こえたとおりの短い形で発音しましょう。

「th」の音: tooth /tuθ/, hypothesis /haɪˈpɒθɪsɪs/, pathogen /ˈpæθəd͡ʒn̩/, pathogenic /pæθəˈd͡ʒɛnɪk/, thresher /ˈθɹɛʃə(ɹ)/
「sh」と「zh」の音: wash /wɑʃ/, inflammation /ɪnfləˈmeɪ̯ʃən/, regulation /ˌɹɛɡjʊˈleɪʃən/, shore /ʃɔɹ/, tissue /ˈtɪʃ.(j)u/
長い単語（アクセントの位置に注意）: mysterious /mɪˈstɪɹi.əs/, ecosystem /ˈikoʊˌsɪstəm/, inflammation /ɪnfləˈmeɪ̯ʃən/, regulation /ˌɹɛɡjʊˈleɪʃən/, orientation /ˌɔː.ɹi.ənˈteɪ.ʃən/

日本語話者が苦手な音：

/r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: regulation /ˌɹɛɡjʊˈleɪʃən/, roughly /ˈɹʌf.li/, rely /ɹɪˈlaɪ/, regulate /ˈɹɛɡ.jə.leɪt/, predictable /pɹəˈdɪktəbləl/
/v/ — /b/ にならないように、上の歯を下唇に当てる: liver /ˈlɪvɚ/, discovery /dɪˈskʌv.ɹi/, visible /ˈvɪzɪb(ə)l/, recover /ɹɪˈkʌvɚ/, convince /kənˈvɪns/
/f/ — 「フ」ではなく、上の歯と下唇で出す: inflammation /ɪnfləˈmeɪ̯ʃən/, roughly /ˈɹʌf.li/, fewer /ˈfjuː.ɚ/, freeze /ˈfɹiːz/, offshore /ɒfˈʃɔː(ɹ)/

この動画での練習方法

まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
自分の声を録音して元の音声と比べます。wash, predator, swimなどの単語に特に注意しましょう。

シャドーイングとは？英語上達に効果的な理由

シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。

シャドーイングのやり方: ステップ別の完全ガイドを読む →

シャドーイング練習: Two Different Things Are Killing Sharks - 動画で英語スピーキングを学ぶ

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