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Science & the Public

Hooking fish, not endangered turtles

Novel tuna-fishing gear may avoid unintended avian and turtle casualties

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A tuna fisherman has taken it upon himself to make the seas safer for sea turtles, animals that are threatened or endangered with extinction worldwide. He’s designed a new hook that he says will make bait — and the lethal barb that secures it — unavailable to marine birds and turtles until long after it’s sunk well below the range where these animals venture to eat.

When I met this Australian, Hans Jusseit, at the Society of Environmental Journalists’ meeting in Miami a few weeks ago, he had yet to sell a single hook. His design had just gone into production and he was hoping to alert the community of commercial longline fishers through us, the media.

He might have more success targeting newsletters and the specialty press who focus on commercial fishing. But I for one was happy that Jusseit showed up at our meeting to exhibit a little tech aimed at making the environment a bit greener. I recognize, however, that he might be just as interested in putting a little more green into his own pocket — since fishing, these days, is in dire straits. And every turtle or bird that removes bait from a longliner’s hooks might be viewed as taking money from his pocket.

Jusseit’s new device, which he calls the “smart tunahook” (photo at upper right), is fairly simple. He’s created a large round shield that crews snap over a fairly standard baited hook. A typical longline deployed by tuna fleets might run up to 150 kilometers. A single line may carry from 1,000 to 3,000 barbed hooks — one spaced every 50 meters or so. “Tuna longline fishing sets over 2 billion of these hooks globally each year,” Jusseit says.

Taking aim at bycatch
His industry has taken heat for its inadvertent removal — termed bycatch — of nontargeted species. For instance, tuna longlining “is responsible for catching hundreds of thousands of seabirds and turtles each year,” he says, “and has brought some albatross species close to extinction. Like the Amsterdam albatross; there’s only about 80 left on the planet.”

I haven’t been able to check his stats. But in their September 14 final rule listing loggerhead sea turtles as endangered or threatened, the U.S. Fish and Wildlife Service and National Oceanic and Atmospheric Administration did credit fishing’s inadvertent snagging (and drowning) of turtles as a leading cause — if not the leading cause — of adult turtle mortality associated with human interactions.

Each of Jusseit’s new palm-sized tuna-hook shields, made from a mild steel alloy, serves as a sinker to ferry a hook down to perhaps 50 meters or more below the surface.

Some 10 to 20 minutes after hitting salt water, corrosion of a pin in the shield will rust through, allowing the guard to fall away to the ocean floor, where it’s supposed to rust away to nothingness within a year. A now-unencumbered baited hook is free to snare some ravenous 50- to 400-pound tuna, billfish or other large denizen of the mid-water-column.

Jusseit’s company has financed independent tests of the hook in New Zealand. He says these showed albatrosses and petrels can’t get hooked on it as they grab for bait. The National Marine Fisheries Service also tested the shield with sea turtles, he claims, and showed the big reptiles can’t swallow it or get at a protected hook.

“We’ve shown in tests on longline boats in Australia that fishermen catch more fish using this hook,” Jusseit reports. One reason: Seabirds and turtles typically abscond with up to 15 percent of the bait. The heavy new guards also will substitute for pricy sinkers used to initially pull the hooks down to the target depths, he says.

Each disposable smarthook guard costs 20 cents — or about $200 each time a longline is baited. “But that’s the price of about one tuna,” Jusseit notes. “So catching just one more fish would pay for them.”

Top predators as top targets
His device sounds clever. But only if you buy into the idea that fishing for the marine world’s top predators is a good thing. Many marine conservationists don’t.

Increasingly, studies have shown that depleting the seas of sharks, billfish, cod, tuna and other fish-eating fish — the sea’s equivalents to lions on the Serengeti — leave prey species to mushroom in abundance (SN: 4/9/11, p. 28). By selectively taking the top predators, marine analogs of rats and overgrazing antelope can now proliferate unchecked.

Targeting the seas' big carnivores also has depleted to perilous levels the stocks of many fish that people find most appetizing (6/4/05, p. 360). In fact, the recent federal assessment of risks to loggerhead sea turtles noted that longlining is diminishing as a threat — but only because the fish these fleets had targeted are themselves so depleted that many longliners now limit their activities.

The deaths of animals that weren’t targeted and won’t be eaten — not only birds and turtles but also fish and sometimes porpoises — needlessly exaggerates fishing’s environmental footprint (or should it be splashprint).

It’s against that context of mountainous bycatch that inroads like a smarter hook constitute a development that's greenish, if not a deeply emerald hue.

Citations

National Oceanic and Atmospheric Administration and United States Fish and Wildlife Service. Endangered and Threatened Species; Determination of Nine Distinct Population Segments of Loggerhead Sea Turtles as Endangered or Threatened (Final Rule). September 14, 2011. [Go to]
Further Reading

J. Raloff. Big fishing yields small fish: Researchers map predator loss and predict unstable oceans. Science News, Vol. 179, April 9, 2011, p. 28. Available online: [Go to]


J. Raloff. Empty nets: Fisheries may be crippling themselves by targeting the big ones. Science News, Vol. 167, June 4, 2005, p. 360. Available online: [Go to]

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