Red Herring

Episode Summary

Executive Summary: Radiolab tells the story of how Sweden’s Cold War submarine panic led to years of secret investigations into mysterious underwater “typical sounds,” only for scientists Magnus Wahlberg and Håkan Westerberg to discover the culprit was not Soviet subs but massive schools of herring releasing air bubbles—essentially a long-running fish-fart illusion amplified by military assumptions and secrecy.

Main Topics: Cold War fear in Sweden: The episode opens with Sweden’s anxiety about Soviet threats across the Baltic Sea, framing the 1981 Soviet sub grounding as a defining national shock. The 1981 and 1982 submarine incidents: Two major submarine scares—one beached sub in 1981 and repeated sightings near Stockholm in 1982—triggered military alarms, public fear, and expensive coastal surveillance efforts. The mystery of the 'typical sound': For years Swedish hydrophones detected a classified sound treated as proof of Soviet submarines, though no one outside the military was allowed to hear it or verify it. Scientific intuition and the herring hypothesis: Magnus and Håkan, experts in underwater biology, suspected the sound came from herring releasing air through a swim bladder canal, producing bubble-like noises. Experiments to test the sound source: The scientists first tested dead and live herring in controlled settings, then in the wild with schools of fish, eventually reproducing the military’s 'typical sound.' Secrecy, confirmation bias, and military culture: The story critiques how top-down secret systems can reinforce mistaken interpretations, with the military interpreting ambiguous sonar data as advanced enemy submarines. Humor and humility in science: The ending reflects on how a seemingly absurd discovery reveals both the power of science and the possibility that today’s certainties may someday look just as misguided.

Key Arguments: The Soviet submarine scares were real political and psychological events for Sweden, but the evidence behind the repeated alarms was weak and highly interpretive. The 'typical sound' was not a submarine signature; it matched the collective noise of herring releasing air bubbles underwater. Military secrecy and hierarchical decision-making prevented open scientific scrutiny, allowing a mistaken explanation to persist for more than a decade. Sonar can detect patterns, but without openness and verification, observers can mistake natural phenomena for hostile technology. The story is a cautionary tale about how institutions can build elaborate theories around incomplete data, then defend those theories with more evidence-seeking instead of skepticism.

Data Points: Distance across Baltic Sea: about 140 miles - The narrator describes the water separating Sweden from the Soviet Union as a short but ominous stretch of sea. Year of first major incident: 1981 - A Soviet submarine ran aground in Sweden, becoming a defining Cold War moment. Age of Magnus Wahlberg in 1981: 13 years old - Magnus recalls experiencing the submarine scare as a child in Stockholm. Swedish coastline length: over 1,000 miles - The military struggled to patrol Sweden’s long, complex coastline. Length of secrecy around the sound: 15 years - The 'typical sound' remained classified and unheard by civilians for about fifteen years. Frequency of later incidents: 20 to 30 incidents every year - During the 1990s the military continued to report numerous submarine alerts annually. Year the sound was officially reclassified: 1999 - The navy accepted that the typical sound was caused by herring, not submarines. Scale of herring schools: up to a square kilometer; billions of fish - The scientists reasoned that the sound came from large, coordinated schools of herring.

Pivotal Quotes: "the typical sound" — Swedish Navy officers / narrator: The classified audio signature the military treated as evidence of Soviet submarines. "This is definitely not the sum." — Magnus Wahlberg and Håkan Westerberg (paraphrased in dialogue): Their immediate private reaction upon hearing the secret recording during the naval briefing. "the sound of thousands and thousands. Thousands of herring all farting together." — Narrator: The final scientific explanation for the mysterious underwater signal.

Implications: The episode shows how secrecy and bias can distort interpretation, while science requires openness, testing, and humility. It also suggests future institutions should treat anomalous data cautiously before building threats around them.