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What Happens to Fish When Our Pills Reach the Water?

How To Protect The Ocean

Release Date: 09/30/2026

How to Read the Seafood Counter Like a Marine Biologist show art How to Read the Seafood Counter Like a Marine Biologist

How To Protect The Ocean

Picture a big sign over the seafood counter promising sustainable fishing, with a fish every independent guide says to avoid sitting on ice right below it. In most countries nobody broke a rule, because the word "sustainable" on seafood has no legal definition. In this final episode of our sustainable seafood week, Andrew Lewin walks you through how to see past that sign and choose seafood you can feel good about. You'll learn how to use the eco-labels and seafood guides that have already done the research for you, including the Marine Stewardship Council's blue tick for wild seafood, the...

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Is Bottom Trawling Always Bad? It Depends Where show art Is Bottom Trawling Always Bad? It Depends Where

How To Protect The Ocean

Off the south coast of England, about 100 kilometres out, sits Haig Fras, a granite reef covered in jewel anemones and cup corals. For years it was protected on paper, yet heavy fishing gear could still drag across it. In March 2024, that finally changed. In this episode, Andrew Lewin explains why where we fish matters as much as how much we fish, and what it takes to turn a line on a map into real protection. Andrew breaks down the difference between midwater and bottom trawls and puts the damage shown in the recent Ocean documentary into context. Bottom trawling lands about a quarter of the...

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The Trapdoor That Saves Sea Turtles From Shrimp Nets show art The Trapdoor That Saves Sea Turtles From Shrimp Nets

How To Protect The Ocean

A Kemp’s ridley sea turtle, the most endangered sea turtle on Earth, gets swept into a shrimp trawl. It hits a metal grid, slides out through a flap in the net, and swims away. That small trapdoor, the turtle excluder device, is one of the biggest success stories in fisheries management, and in late August 2026 a US federal appeals court upheld the rule extending it to skimmer trawl boats 40 feet and longer. In this episode, marine biologist Andrew Lewin walks through the bycatch fixes that are working and the fights still underway. You’ll hear why North Atlantic right whales get tangled...

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The Cod Came Back: What a Fishery Collapse Teaches Us About Overfishing show art The Cod Came Back: What a Fishery Collapse Teaches Us About Overfishing

How To Protect The Ocean

Five centuries ago, explorers off Newfoundland described cod so plentiful that a weighted basket lowered into the sea came back full. By July 2, 1992, so few remained that Canada shut the northern cod fishery overnight. About 30,000 people lost their work in what became the largest single layoff in Canadian history. In this first episode of a week-long sustainable seafood series, Andrew tells the story of how the collapse happened and how slowly the cod came back. Andrew then breaks down the words that cause the most confusion in fisheries headlines: overfishing, overfished, depleted, and...

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How to Choose Sustainable Seafood show art How to Choose Sustainable Seafood

How To Protect The Ocean

You want to eat seafood the right way. Then you hit the seafood counter and face a wall of labels, a sign promising “sustainable practices,” and an employee who has no idea where the tuna came from. Add documentaries like Seaspiracy telling you to quit fish entirely, and it’s tempting to give up and buy whatever looks good. Unsustainable fishing is the biggest threat to marine biodiversity, so those choices carry real weight. In this episode, Andrew’s good friend Dr. David Shiffman joins the show to talk about his new book, Why Sustainable Seafood Matters. David spent two years on the...

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Slow Down for Whales: How Global Shipping Learned to Share the Ocean show art Slow Down for Whales: How Global Shipping Learned to Share the Ocean

How To Protect The Ocean

Blue whales can’t dodge ships. When scientists tracked blue whales alongside cargo ships off Southern California, the whales responded in just over half the encounters, and every response was the same: a slow, shallow dive. Not once did a whale move sideways out of the ship’s path. Models suggest ships kill around 18 blue whales a year off the U.S. West Coast, nearly eight times what the population can lose and still recover. The good news is in the data. Most blue whale strike deaths happen in a small slice of ocean, and that’s where ports, air quality agencies, marine sanctuaries, and...

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When Whale Food Moves: Climate Change, Crab Traps, and Pop-Up Gear show art When Whale Food Moves: Climate Change, Crab Traps, and Pop-Up Gear

How To Protect The Ocean

In 2014, a patch of unusually warm water nicknamed "the blob" settled off the west coast of North America. The cold, food-rich water that normally stretches far offshore shrank into a narrow strip along the coast, and hungry humpback whales followed their food straight into the waters where Dungeness crabbers had set thousands of traps, each tied to a vertical rope. Entanglements jumped from about 10 a year to 53 in 2015 and 55 in 2016. In this episode, Andrew traces the line from warmer water to a specific whale in a specific rope. You'll learn why lunge-feeding whales depend on dense patches...

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The Whale Heart That Beats Twice a Minute show art The Whale Heart That Beats Twice a Minute

How To Protect The Ocean

Fill your hands with cold water, hold your breath, and press your face in. Your heart slows within seconds. That reflex lives in every whale in the ocean too, and in a blue whale it is pushed so far that the largest heart on Earth can drop to two beats a minute on a deep dive. In this episode, Andrew walks through the first heart rate recording from a wild blue whale, led by Jeremy Goldbogen's team at Stanford, and a study by Terrie Williams of UC Santa Cruz that tracked narwhals fleeing after release from nets in East Greenland. The narwhals swam as hard as they could while their hearts fell...

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The Biggest Mouthful: How Blue Whales Eat and Why Krill Matters show art The Biggest Mouthful: How Blue Whales Eat and Why Krill Matters

How To Protect The Ocean

A blue whale can swallow a volume of water bigger than its own body in a single gulp. That move, called lunge feeding, is one of the most extreme feats in the animal kingdom, and it only pays off when krill is packed into thick, dense swarms. In a thin patch, a blue whale gets back about six times the energy it spent. In a dense swarm, it gets back more than 200 times. In this first episode of the Age of Giants series, Andrew breaks down how rorqual whales feed, then follows the krill. In 2025, the Antarctic krill fishery hit its 620,000 tonne precautionary limit for the first time and closed...

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Whales Are Sprinters: What a Blue Whale's Heart Does When It Lunge Feeds show art Whales Are Sprinters: What a Blue Whale's Heart Does When It Lunge Feeds

How To Protect The Ocean

What happens to the heart of the largest animal on Earth when it charges into a swarm of krill? Dr. Ashley Blawas, a postdoctoral scholar in Jeremy Goldbogen's lab at Stanford's Hopkins Marine Station, joins Andrew to unpack new research published in PNAS that measured the heart rates of lunge-feeding blue whales and humpback whales using suction-cup ECG tags. Ashley explains the three phases of lunge feeding (accelerate, engulf, filter) and why these giants behave a lot like human sprinters. Their heart rates stay high after each lunge, then gradually recover while they glide and filter,...

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More Episodes

In 2001, government scientists started adding a tiny amount of the synthetic estrogen found in birth control pills to a remote lake in northwestern Ontario, at levels already measured in city wastewater. Within seven weeks, male fish were making egg-yolk protein. After two summers, some had eggs growing in their testes, and the fathead minnow population collapsed to about 1% of normal. Andrew explains how the same chemistry leaves our bodies every day, passes through treatment plants built for sewage and bacteria, and flows into rivers, lakes, and the coast.

Hormones are only part of it. In Sweden, researchers at Umeå University found that perch exposed to the anti-anxiety drug oxazepam, at levels matching wild fish, became bolder, fed faster, and drifted away from their schools, all behaviours that make a small fish easier to eat. Andrew then goes back to DDT, when bald eagles fell to 417 nesting pairs in the lower 48 states before the 1972 US ban let them climb past 71,000 breeding pairs.

The recovery story continues at Lake 260. Once the hormone additions stopped, the minnows came back to pre-experiment levels within three years. Switzerland is now upgrading about 120 treatment plants with ozone or activated carbon to remove more than 80% of these micropollutants, paid for by a small annual fee per person. Andrew closes with the part you control today: take your leftover and expired medications back to a pharmacy.

Takeaways:

  • Your body doesn't use every bit of a pill, and what's left leaves in urine.
  • Most treatment plants remove solids and bacteria, and many drug compounds pass straight through.
  • At Lake 260, synthetic estrogen at about 5 to 6 nanograms per litre collapsed the fathead minnow population to about 1%.
  • Lake trout that ate those minnows declined too.
  • Oxazepam made perch bolder, faster feeders, and loners, raising their risk from predators.
  • Bald eagles went from 417 nesting pairs in 1963 to more than 71,000 breeding pairs after DDT was banned.
  • Lake 260's minnows recovered within three years once the hormone additions stopped.
  • Switzerland is adding ozone and activated carbon treatment to about 120 plants to remove more than 80% of micropollutants.
  • Ontario's free pharmacy return program collected more than 330,000 kg of medications in 2024.
  • Keep taking what your doctor prescribes, and return the leftovers to a pharmacy instead of flushing or trashing them.

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