Sing Like Fish by Amorina Kingdon

Author:Amorina Kingdon [Kingdon, Amorina]
Language: eng
Format: epub
Publisher: Crown
Published: 2024-06-04T00:00:00+00:00

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The Bass Strait separates the state of Victoria, Australia, from the island of Tasmania. More than twenty oil and gas platforms dot the waters, and seismic surveys take place regularly. The strait is also a fishing ground for scallops and lobsters, and in 2011 the Tasmania Scallop Fishermen’s Association blamed a recent seismic survey for the loss of 24,000 tons of scallops and tens of millions of dollars in income. Had the air guns killed the scallops?

Jayson Semmens is a marine biologist at the University of Tasmania, and he wondered how seismic air-gun sound might affect commercial species. He was also with IMAS, so he collaborated with McCauley and others to set up an acoustically rigorous test. The team collected wild lobsters and scallops and moved them to test sites in the sea alongside a hydrophone, a geophone, and a video camera. Then they fired an air gun in the water above and gave the animals a thorough exam.

No lobsters died. Many females were full of eggs that developed normally. But the rest of the news was less good.

Basically, the lobsters lost their balance. These crustaceans have a reflex to right themselves if they’re flipped on their back, but after the air guns were fired, they took more than twice as long to do so. When Semmens looked closely at the lobsters’ statocysts, fluid-filled sacs lined with sensory hair cells at the base of the antennae, the hair cells were damaged—the hairs “sheared off,” as he puts it. Since statocysts sense gravity and orientation, this would obviously upset their coordination. Lobsters’ blood chemistry changed, too, in ways that suggested a trauma response, leaving them more vulnerable to infection.

As for the scallops, changes in their “blood,” a fluid called hemolymph, suggested chronic compromised immunity. And many scallops later died, with deaths peaking three months after the experiment. That pointed at trauma with a long tail, the kind that doesn’t kill outright but insidiously. If one didn’t know what to look for, a casual glance might have suggested the scallops were fine.

Semmens says he could see the air gun had caused a physical shock. The lobsters were on a rocky limestone site, while the scallops were sitting on a sandy bottom, and in the video of the scallop test, Semmens saw the sand jumping with the force. Whether the physical shock or the stress of the sound caused the problems in the animals, he couldn’t tell. Either way, there was a literal impact.

Semmens got a lot of “grief,” as he puts it, from the oil and gas industry for this study. They claimed a single gun wasn’t equivalent to an array and the water was far shallower than real-world conditions. The only way to know was to use a commercial array. So that’s what he did next.

Working with a seismic prospecting company is logistically challenging, as McCauley describes. But Semmens was determined. He even included juvenile lobsters in his study, understanding that effects on young animals could have bigger cumulative effects throughout the life cycle.

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