Kurt Lieber, Founder and President of Ocean Defenders Alliance kicks off our series on ‘Ghost Nets,’ featuring Mission Blue partners who are leading the charge to publicize – and remedy this growing and very dangerous problem for sea life. We’ve also embedded the just-released video from Jamie Thalman on ODA’s work, ‘Catalina Wrecked.’
We are proud to welcome Ocean Defenders Alliance to the Mission Blue family of Partners! ~ Ed.
There is a long-neglected issue affecting our planets oceans. It is not that people don’t care; it is more a classic example of “out of sight, out of mind.” Most people are outraged when they see images of garbage or clear-cuts in national forests—but too few people understand that our oceans face similarly devastating circumstances in the form of “ghost” fishing gear. In this article, I will help you understand this important and deadly issue.
Studies on the impact of marine wildlife from abandoned fishing gear only began in the late 1980’s. As a consequence, not a lot is known about the long-term damage this gear causes, and the majority of current data is empirical. It is estimated that fishermen lose 10 to 15% of their gear every year.
Ghost gear is best described as being abandoned, lost, or discarded fishing gear that continues to kill, injure, harm, or inhibit marine wildlife. In this article I will touch on many of the gear types that plague our oceans.
Driftnets and gillnets are THE most deadly, since they are made out of monofilament and are virtually invisible underwater. Driftnets are huge curtains of net that hang in the water column and can stretch to 60 miles long! These “curtains of death” are indiscriminant killers, catching whales, dolphins, turtles, sharks, sea birds, and just about anything else that swims. These nets were banned by the United Nations General Assembly in 1995. At the time of the moratorium there were so many driftnets in the world’s oceans that they could have circled the globe 5 times each day. Although the ban remains in place, driftnets are still widely used by poachers in international waters.
Gillnets are made from monofilament line just like driftnets, the only difference is that they are not as long, and are designed to catch “targeted” species of fish, like salmon and tuna. They do this by creating the nets to a specific mesh size intended to allow smaller fish to escape. However, incidental entanglement by whales, dolphins and turtles is an all too common occurrence. Gillnets are banned in the waters of the State of California, which extend from the beach to 3 miles offshore.
To give you an idea of how troubling the “accidental take” can be: in 2008 we located an abandoned gillnet about 4 miles outside of the LA Harbor. It was in 100 feet of water, and was about 4,000 feet long. Our divers were only able to swim alongside it for 100 feet. In that brief 100-foot span, they found the carcasses and skeletons of 21 dead sea lions, a dozen cormorants, and several crabs. We have no idea how many other animals were killed by that single piece of ghost net—but it was many.
Longlines are another curse. These lines can be up to 60 miles long and have up to 2,500 baited hooks on each one, spaced about 10 feet apart. These are used to catch swordfish, halibut, tuna and sablefish. As you can imagine, there are a wide variety of animals that are killed unintentionally. Animals like turtles, seabirds and sharks. They are set throughout the world’s oceans, and in fact, there are so many set at any given time that if these killing-lines were laid end to end, they would wrap around the earth 550 times…EVERY year!
Dungeness crab traps are another example of gear that continues to fish and kill long after becoming lost. Another is the finfish trap, which is used throughout the world to catch fish for the highly lucrative “live fish” trade supplying live fish for Asian and other restaurants.
The second is “derelict gear,” which is generally characterized as not actively killing fish, but still occasionally traps and kill fish and other marine life for some time after it is lost. This consists of various other traps and cages.
One example is lobster traps. It has been observed that lobsters can move in and out of the traps freely, as long as the trap door is open.
In California, lobster traps are required by law to have a latch on the door that is made of a material that disintegrates after one year of immersion in saltwater. While this works fine in theory, I have seen many, many traps with bungee cords wrapped around the door, so even though the latch dissolves over time, the door is still secured shut by the cord. This is illegal, but common…and results in needless waste and death.
Another by-product of lost traps and pots are the floats and lines that are attached to them. The lines are made out of polypropylene and are lighter than water, thus they float in the water column. A recent study by NOAA documented an average of 10 whale entanglements every year along the Pacific coast of the US. Of those 10, 3 to 4 of the whales die. The majority of these slow deaths have been traced to entanglement in lobster trap or Dungeness crab trap lines.
Ghost fishing gear is far more deadly than derelict gear, as it is usually made out of synthetic material: polypropylene or nylon. Both are petroleum products (plastic) that will last for hundreds of years in the oceans. Plastics were invented in the early 1900’s, which is a relatively short time ago, so there is no actual proof of its longevity, but accelerated aging tests estimated that polypropylene will last 450 years, and nylon 650 years, in sea water—with both lasting much longer in fresh water.
One of the hidden “charms” of plastic is that it is made of chemicals that can kill marine organisms. How does this happen? I was hoping you would ask. Plastic is made from petrochemicals known to be toxic to humans and wildlife. These toxins can lead to a variety of ailments: from suppression of the immune system, to a range of cancers, and of course death.
While scuba diving, I have seen many thousands of feet of polypropylene line meandering around rocky reefs. While it may look harmless, on closer inspection you will see a lot of organisms around these lines that are either dead or dying. One such animal is the gorgonian. This is an animal that looks like a marine version of a tree, but is actually an animal that has an exoskeleton. That means their skeleton is on the outside of their body. When plastic comes in direct contact with these and other life forms, toxins from the plastic are absorbed into their body. They don’t have any skin to protect them. When in direct contact with the line, over time, the animals die from exposure to the chemicals.
Another way plastic can kill is when a net is in the water for a long time and encrusting organisms inevitably start to latch onto the material. Crabs, lobsters, and other crustaceans will start to pick at those little organisms (natural crustacean food) and accidentally ingest small pieces of the net as well. This material is absorbed into their tissue, and later consumed by other predators. These chemicals continue to move their way up the food chain until it reaches THE top predator of the oceans, and I don’t mean sharks, I am talking about…humans. Directly and indirectly, humanity also suffers as a result of ghost/derelict gear.
Derelict gear like traps and crab pots have been documented to last up to 3 years in shallow waters before they start to collapse due to breakage and encrusting organisms. But in deeper waters they will last significantly longer because they are not subject to the wave action, sunlight, and tide motions that accelerate the breakdown process in shallow waters. The traps and pots can become battering rams when storms create big waves and tidal surges that toss them around. When winter storms turn the seas into violent cauldrons, this debris is tossed around and acts like battering rams when thrown against reefs, kelp beds, and other ocean structures, thus reducing the structural complexity of the habitat.
A study done by researchers from the University of North Carolina, Wilmington, documented the effects of abandoned lobster traps on sea grasses in coastal areas of Florida. These sea grass beds are home to many species of fish and crabs and are a nursery for many species that seek shelter there while young and later migrate to deeper waters as they become larger (for example: swordfish and marlin). This study found that a single trap can travel up to 100 feet in six months, leaving a trail 4-6 feet wide and 100 feet long, leaving nothing but sand in its wake.
Nets Kill Marine Animals for Decades
A different study, this time performed by the Northwest Straits Initiative in 2007, concluded, “it is estimated that one net left derelict for 12 years may have killed 5,000 animals, including 1,000 birds.” One of the reasons that it is really difficult to quantify how many animals die in these nets is that the bodies of the victims become an easy meal for scavengers and within 3-7 days there is nothing left to identify. It is that die/scavenge cycle that also exacerbates the problem—as dead animals serve as “bait” that lures in other animals to the same unfortunate end.
When encrusting organisms and algae colonize the nets and their attendant floats, they will eventually sink to the bottom. While this might seem like the end of the destruction, that is not necessarily the case, as this debris now smothers benthic life and hinders the growth of native species. The deadly nets thus also create an opportunity for invasive organisms to colonize.
I have witnessed with my own eyes the silent rampage this gear perpetrates on ocean wildlife. Once settled on the bottom, the nets attract crustaceans, like crabs and lobsters that start feeding on the tiny organisms that have attached themselves. The crustaceans then become entangled in the nets mesh and either die or, worse yet, attract large fish, seals, sea lions, sharks, and dolphins looking for an easy lunch. All it takes is one flipper or fin becoming ensnared. Now, another life will be silently taken.
While working on a site just off the coast of Catalina Island, California a couple of years ago, we found a net that had been recently abandoned. In it were six dead sea lions. As our divers were cutting the carcasses out of the net, we discovered dozens of fish trapped in it as well. Most were already dead, but our team was able to liberate eight of them. Most of those were rockfish. There are several different species that fall under the banner of rockfish, some of which are estimated to live up to 200 years!
The Impact of Sunken Vessels
While many countries have been quick to jump on the bandwagon of sinking surplus ships to serve as artificial reefs, the dark side of that movement is just being revealed to us.
We’ve been convinced by our governmental agencies that once these vessels have been “decontaminated” and stripped of their wiring, asbestos, and other chemicals, they are safe for the marine environment. This has lead to hundreds of ships being scuttled to attract fish, scuba divers, and eco-minded tourists to areas severely degraded by other human activities.
Because this is a relatively recent phenomenon, few long-term studies have been done. Notably: in May of 2012, the US Maritime Administration immediately halted all future ship sinkings after discovering that the areas around these metallic reefs are polluted and fish are contaminated with high levels of PCBs that emanate from the wrecks. While the program is still theoretically in place, NONE of the ships previously set aside were deemed suitable for becoming reefs. It seems all ships built before 1985 have toxins on them that cannot be removed to sufficiently meet clean water standards.
Now we can look at a similar phenomenon that has being happening ever since humans took to the seas in boats: many old or derelict boats have been sent to the bottom by individuals thinking they will become fish attractors. Most of these boats were not cleaned beforehand. So you can imagine how toxic many of these vessels are to wildlife.
With the recent downturn in the economy, many boat owners can no longer afford to maintain their boats, let alone pay related insurance and slip fees. When they get too far behind in their payments, rather than paying to have the boat properly disposed of by a salvage company…many people find other ways to make the problem “go away.” For example, here in Southern California we have one of the world’s most fabled destinations for boaters, fishermen, and scuba divers: Catalina Island. While it is a paradise both above and below the water, more and more boats are finding their final resting place on the sea floor. Within the last 24 months, we have documented 21 boats going down under suspicious circumstances. Please take three minutes to watch our video called “Catalina Wrecked.” http://catalinawrecked.com/
Our oceans are under constant assault from humans. Whether from overfishing, coastal development, runoff from urban streets and agricultural sources, or dumping of pollution directly into the seas, we need top end these harmful practices while proactively removing as much of the pre-existing garbage as possible—before we end ocean life entirely.
With so much information available to us, we know what needs to be done, and it is up to us to have the resolve to “dive in” (literally and figuratively!) and clean up this planet. We must do this not just for our own sake, but because the fate of future generations of human and ocean life depend on us.
Removing ghost gear and marine debris is one tangible way to become involved and be part of the solution. Our children will thank us.
By Kurt Lieber, Founder and President of Ocean Defenders Alliance
Ocean Defenders Alliance (ODA) is a marine conservation nonprofit organization founded in 2002. ODA works to clean and protect marine ecosystems through documentation, education, and meaningful action. Working with affected communities, we focus on the reduction and removal of man-made debris that poses serious threats to ocean wildlife and habitats. Please visit ODA’s website: www.oceandefenders.org