Orcas and Sharks Strike an Anchor Chain at Bremer Canyon

A crew of Western Australian fishermen say sharks struck their anchor chain within seconds of a pod of orcas circling their boat, transforming an ordinary dawn set into a burst of raw adrenaline. At Bremer Canyon, where the continental shelf falls away and the sea deepens, apex predators can cross paths. What does that feel like when your boat is caught between them?

The crew had only just dropped the pick. The kettle was hissing, spray had made the deck slippery, and the chain gave its usual soft clatter as it paid out. Then the orcas broke the surface in a broad circle, their breaths pumping like pistons, and everyone aboard fell silent.

Their anchor line thrummed under load as the swell passed beneath them. A minute later, there was a blow like a sledgehammer hitting steel. Then another. The chain jolted. “Sharks,” somebody said, and no one disagreed. Then the noise shifted.

When orcas meet sharks - and your boat is caught in the middle

Fishermen often say the sea starts telling its story before you know how it ends. Orcas circling a vessel do not always signal danger, but it never seems routine. Tails twitch, dorsal fins disappear, bursts of breath linger like cold smoke, and the water around the hull becomes a shifting pattern of living movement.

That morning off Western Australia’s south coast, the crew used their radios to contact a nearby cray boat. One deckhand captured a wide video shot despite trembling hands, recording the anchor chain’s sharp jolt as a shark’s head hit the metal. There was no blood in the water and no bait deployed. There was simply an anchor line that suddenly seemed important to every creature below.

Marine biologists say orcas can drive sharks away as easily as pigeons, at times rolling them over to trigger tonic immobility. Sharks are primed to follow vibrations, electrical fields and the distress signals of prey. An anchor chain held taut in a surge, tight like a guitar string, sends noise and electrical charge through the water. With orcas working around its edges, the result can be confusion and impacts.

Staying safe when apex predators gather around your gear

When orcas come close while you are anchored, become still. Stop unnecessary noise, fasten loose lines and keep your hands clear of the gunwale. Maintain steady chain tension rather than hauling sharply; abrupt changes can intensify the sound “halo” that attracts sharks. If the pod remains nearby and the chain is being struck, be ready either to pay out a controlled few metres or to motor slowly ahead and introduce slack, before recovering the anchor once the area is clear.

Broadcast your position and circumstances by radio. Put on PFDs. Keep knives accessible for emergency line cutting rather than brandishing them. Do not throw scraps overboard or wash fish-scented water into the sea in an effort to “distract” the animals. Filming can wait until the boat is secure. We have all experienced the moment when curiosity overtakes caution. The sea does not mark on a curve.

Experienced skippers say calmness is the only real advantage when the water becomes crowded. Do not cut corners with the fundamentals: communicate clearly, move slowly and have a clean departure plan. Allow the animals to establish their pecking order away from your metalwork. Let’s be honest: nobody actually does that every day.

“You feel it in your feet before you hear it,” said one skipper who watched his bow dip with each slam. “Like the boat is a tuning fork and something down there’s playing it.”

• Keep hands and feet inside the rails. Do not lean over to “spot” fins.
• Ease the chain to reduce its tension “singing”, or introduce slack to interrupt the vibration.
• If it is safe, move the boat a few lengths to reset the sound field.
• Record the encounter: time, GPS position and species observed. It may help the next crew.

What the encounter might really mean

Most fishermen neither romanticise orcas nor dread sharks. They interpret them. In this case, the orcas appeared to be herding fish near the surface, while sharks responded to the noise and electrical charge surrounding an anchored hull. The chain became the drumbeat at the centre of a moving orchestra. The crew felt as though they were standing on its stage.

Researchers monitoring orca-shark encounters in the Southern Ocean have found that sharks may leave prime feeding grounds when orcas arrive. The sharks are not necessarily targeting boats. They respond to the quickest and loudest stimulus available. A strained steel chain can be precisely that. Picture the brightest light in a dark room abruptly being switched on.

The sea behaved as it always does: it tested everyone’s composure. Broadly, the risk is less about animals “attacking” than about becoming the loudest object during a tense encounter. By reducing the signal - lowering vibration, limiting protrusions and waiting for the disturbance to pass - a boat can move from the centre of attention into the background. That change creates a margin of safety.

Humans also bring a secondary wave of stress aboard: noise, speed and urgency. The crew that remained quiet, adjusted the chain tension and gave the animals space saw the commotion settle sooner. One orca slapped its tail, the sharks moved away, and the pod drifted off with the unhurried authority that only orcas possess. At last, the kettle boiled. The deckhand laughed with his whole body. No one forgot the moment.

The aftertaste of a near-miss at sea

By the time they returned to the pier, the stories had grown fins. They always do. Some crews had heard the impacts; others said the pod simply passed by and left the sea calm. The shared element was that charged instant when people understood they were not in control. Out there, status belongs to those with teeth and skill.

Standing on a small deck while the chain hums teaches humility. Your equipment does not merely catch fish; it also sings to the wild. That song is not always welcome. In these unusual moments - when orca tactics meet shark instinct - you become the accidental DJ, lowering the volume until everything settles.

Are such encounters becoming more common, or are they simply recorded more often? It is difficult to tell. Phones are everywhere, as are inquisitive people. What stays with you is the pattern: black fins forming a circle, steel rattling, and a heartbeat felt through the soles of your boots. Tell the story, debate it and ask veteran hands how they would respond. The ocean gives its answer slowly, one wave at a time.

Key point	Detail	Why it matters to the reader
Orcas can scatter sharks	Pods force sharks away from feeding areas and trigger flight responses	Helps explain abrupt changes in animal behaviour near your boat
Anchor chain “sings”	Tensioned metal produces vibration and electrical charge that sharks can detect	Explains why sharks may strike the chain and how to reduce the likelihood
Calm beats speed	Slow adjustments and clear communication can de-escalate the situation	Provides practical steps to reduce risk on small decks

FAQ:

• Did the sharks attack the boat? Fishermen said sharks hit the anchor chain rather than the hull. This appears to be a response to vibration and tension, rather than a deliberate “attack”.
• Why would orcas circle a fishing boat? They may be hunting nearby, investigating engine noise or using the boat as a visual barrier while herding prey.
• What should crews do first? Stay quiet, control chain tension, keep limbs inside the boat and radio nearby vessels. Keep hands clear of the rode and windlass.
• Is it safer to cut the anchor? Only as a final option if the risk of entanglement or collision rises sharply. Before sacrificing equipment, try creating slack or moving the boat a few lengths.
• Could this damage the anchor gear? Yes. Repeated hard strikes can strain the chain, swivels and bow roller. Check all hardware after serious contact and replace worn components rather than hoping for the best.