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Abandoned fishing nets: The irony of the sea that keeps on catching (and killing)

Co-authored by Erica Cirino

It was a cool morning in early spring when a group of volunteer divers jumped off their boat into the calm, turquoise waters off Makronisos Island in Greece. Under the surface lay before them lay a vast reef wonderland, complete with bizarrely shaped corals, colorful fish and even a dilapidated shipwreck.

The reef off Makronisos is home to more than one hundred marine creatures, from the beautiful blacktip shark to the musically named red cornetfish. But the divers, sponsored by the ocean conservation organization Healthy Seas, had come to Greece not to net fish, but to remove nets from the fishes’ habitat.

On the reef system off Makronisos, as in other many heavily fished regions of the seas, abandoned fishing nets have created a huge problem called “ghost fishing.” It’s a somewhat ironic, yet serious, threat: fishing nets that continue to catch sea creatures long after fishers purposefully discard or accidentally lose their gear and sail away.

Sea turtles caught in abandoned fishing net. Credit: Carl Safina
Dead sea turtles caught in abandoned fishing net. Credit: Carl Safina

Knives ready, the divers cut the algae-covered nets away from the decaying ship, delicate corals and creatures that had survived being entangled. Then they secured flotation devices to the corners of each net to help propel the heavy gear to their boat at the surface of the water. In just five days the divers managed to remove about 75 percent of all nets—mostly trammel and gillnets—from the reef.

All discarded fishing gear, from line and hooks to metal pots, pose a ghost fishing risk. Trammel and gillnets are the most commonly used type of fishing gear used, capturing about one-fifth of all fish caught across the world every year, according to the Food and Agriculture Organization of the United Nations (FAO). It’s the popularity of trammel nets and gillnets—as well as their designs—that make them the worst ghost fishing offenders (not to mention some of the worst bycatch offenders).

Trammel nets and gillnets work similarly: Both are made of mesh that entangles fish by their gills. Both may be one to two miles long and 10 to 50 feet high. (Prior to 1991 when the UN implemented new regulations on these nets, they could run 40 miles in length!) Trammel nets are usually dropped onto the seafloor with weights holding them down and floats pulling them up from the top, creating a solid wall of net. Gillnets are sometimes used this way, or are attached to drifting ships again creating a wall of net in subsurface or mid-surface water to snare different species than are found on the ocean floor.

Last month, the FOA published a report that sheds light on ghost fishing, a longstanding problem that scientists have only recently begun unraveling. One of those scientists includes Safina Center Fellow Eric Gillman, PhD, who served as a consultant to the FAO as it compiled its report.

While the FAO admits studies are lacking in the ghost fishing department, those that exist estimate ghost fishing mortality rates as extremely high, ensnaring at least tens of thousands of marine creatures—including fish, crustaceans, marine mammals, turtles and sea birds—per year.

And when these nets catch animals (especially large animals like sharks, cetaceans and sea turtles) they don’t do so gently: animals’ heads, mouths, fins or limbs become entangled in netting made of material so strong, it’s next to impossible for them to escape. The lines on the top and bottom of the nets are also dangerous—thin and sharp, they can lacerate animals’ bodies, causing infections, loss of body parts and limited movement. For animals that need oxygen to breathe—like dolphins and sea turtles—becoming caught in these nets is a death sentence to drown. Even if freed, these animals may be so injured their ability to move and feed are reduced, causing a slow and painful death.

All that damage is caused by the estimated total of 640,000 metric tons of fishing gear (about 1 percent of the gear fishers use) that’s lost or discarded in the seas every year, according to the report.

Ghost net and sailfish bones. Credit: Carl Safina
Ghost net and sailfish bones. Credit: Carl Safina

To help put an end to this enormous mess, FAO call for better accountability on behalf of fishers, asking them to mark their gear to identify their ownership and to increase the surface visibility of their gear so it’s not accidentally forgotten in the sea. Better net designs and new technologies to track nets could also reduce the number of derelict fishing gear that pollutes the sea every year. And there’s another major need, according to FAO: better management of ghost fishing policies, which suffer from “substantial governance deficits, including in monitoring, surveillance and enforcement.”

On a global scale, the FAO’s recommendations, as well as efforts to safely dispose of old fishing-gear disposal—such as the NOAA Marine Debris Program—can help lessen the deadly effects of ghost fishing. But you can also help: Making sure you keep on top of your fishing gear, retrieving lost gear whenever possible and always discarding old gear appropriately (and any other litter, for that matter!). You can also join volunteer efforts to clean up your local beaches—or even by donating your time to tidy up coral reefs!

As part of the National Aquarium’s 48 Days of Blue campaign, which spans the 48 days between Earth Day and World Oceans Day on June 8, you can find daily challenges to benefit the seas on the aquarium’s website and we’ll be incorporating one challenge per week into our blog posts.

One challenge this week: Join the Litterati! Make at least one effort this week to clean up or prevent trash—such as old fishing gear—from the marine environment. Don’t live near the sea? You can still help: be extra vigilant about how and where you discard your trash this week so it doesn’t end up in the ocean.

Comments

  1. Clifford Goudey
    Massachusetts
    May 17, 12:05 pm

    Passive fishing gear, by design, is lethal whether it’s being tended by a fisherman or abandoned. By contrast, lost trawl nets are benign by comparison and when fished are at least selective based on size and capture in proportion to abundance. Maybe there’s a lesson here.