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Oh, What a Tangled Web We Weave

Fishing lines are snaring the unwanted bycatch

Sometimes plying the same waters as fishermen, North Atlantic right whales can find themselves swimming and feeding amid a gauntlet of ropes attached to gillnets and lobster pots. These fishing lines can get caught in the whales’ comb-like, filter-feeding baleen, or become snagged around their flippers or tails. As the whales struggle to free themselves, they often wrap the lines more tightly.

The whales swim on for months with fishing gear attached, burdened like Jacob Marley dragging his chains through Dickens’ A Christmas Carol. The lines impede their breathing, feeding, socializing, and breeding. The whales often free themselves, but others die from drowning or starvation, if not from infections caused when lines slice into their flesh.

“We would not tolerate watching animals on land undergo such pain and gruesome deaths,” said WHOI biologist Michael Moore.

About 70 percent of the North Atlantic right whale population exhibits scars from fishing gear, said Scott Kraus, Director of Research at New England Aquarium. Rapid response efforts to disentangle whales have been heroic and spectacular (see “The Death of Churchill,” page 15), but finding ways to avoid entanglements is a preferable solution.

The endeavor is challenging, however, because researchers and fishermen only see the results—not how it happened. “Most fishermen will never see a whale entangled in their fishing gear,” said Glenn Salvador, a member of the Whale-Safe Fishing Gear Research Unit at the U.S. National Marine Fisheries Service (NMFS). One fishermen once told Salvador: “Asking me to come up with a solution to this is like asking me how to keep a spaceship from getting entangled in my wife’s clothesline.”

The NMFS unit educates the fishing community about the problem—at industry meetings, on the Web, and by doing “a lot of dock work, talking with fishermen,” Salvador said. The unit also does forensics work, analyzing gear and conducting interviews with fishermen to reconstruct why entanglements occurred.

The NMFS unit, along with private and academic researchers, also conducts research on fishing gear modifications that may decrease or eliminate entanglements. These include developing fishing lines that break rather than obstruct a whale, and changing the buoyancy of lines so that they sink rather than float—minimizing whales’ exposure to lines in areas where they dive.

Norm Holy, a chemist at Atlantic Gillnet Supply Inc., is working to develop rope that is strong enough to haul fishing nets, weak enough to be broken by a whale, and thick enough to avoid cutting into animals quickly. His research involves adding dissolvable salt to the polypropylene material and microscopic “holes” to the microfiber texture to weaken the ropes just enough, but not too much.

Originally published: November 1, 2004