Bonn/Washington D.C. – 9 June 2014- It is not just foreign species that are invading our natural marine habitats; human byproducts are disfiguring marine ecosystems too. Such an unnatural invasion of human-made products has a disproportionate impact on marine life. This deplorable situation is exacerbated by the incorrect belief that marine debris on the other side of the world is somebody else’s problem. The truth is that a connected network of oceans provides a transboundary path along which marine debris can migrate. Oceanic debris is widespread but tends to be most visible along coastlines or in oceanic gyres and coastlines. The migration of marine debris around the world is not unlike the migration of marine species or sea turtles, crossing political boundaries, moving from one territorial sea to the open ocean and ending up on another nation’s waters. It is an issue that concerns everyone globally but belongs to no one nation alone. Marine debris is a local problem in need of a global solution. As a multilateral environmental agreement, the Convention on Migratory Species aims to address this issue working with its 120 members and other countries around the world.
Entanglement in lines and nets can have serious impacts on sharks. A 2002 study found that entangled sharks are susceptible to growth trauma caused by tissue damage resulting from plastic entanglement. The study concluded that the impact of discarded plastic debris is likely to be greater on sharks that inhabit shallow coastal waters. Plastic debris wrapped around a shark’s gill slits or body can cause traumatic cutting into tissue and chronic infection, which may affect the animal’s ability to feed and grow. While the reported number of sharks dying from entanglement is low, this is likely due to the depths reached by sharks and resulting in unrecorded shark deaths.
Sea turtles are particularly vulnerable to the effects of entanglement in marine debris as well as ingestion of plastic bags mistaken for jelly fish, the primary food source of some species. Turtles have downward facing spines in their throats that prevent regurgitation. Trapped plastic lodges in their stomach preventing turtles from properly swallowing. Turtles also are susceptible to a concoction of gases that result from decomposing marine debris causing them to float to the surface (known as “bubble butts”). This prevents the turtle from diving and gathering food, making it an easy target for predators.
Whales, dolphins, and porpoises are vulnerable to entanglement, with coastal species of cetaceans being particularly susceptible as human activities such as fisheries affect their habitats. While entanglement does sometimes lead to death by drowning, studies have shown that it can lead to stunted growth, deformity and greater risk of infections.
Marine debris poses another threat to cetaceans. Both filter-feeding whales and toothed whales such as dolphins can inadvertently ingest debris while they feed. In August 2008 a Sperm whale died on a beach in California with 450 pounds (200 kg) of fishing net, rope, and plastic bags in its stomach. In March 2013 it was found that a sperm whale in Spain had ingested 59 different plastic items totaling over 37 pounds (17 kg). In July 2013 a deceased Sperm whale washed onto the shore of the Netherlands, and a necropsy again revealed the whale had large quantities of plastic in its stomach.
A number of species of sea bird ingest significant and dangerous quantities of plastic, while some ingest hooks and line when scavenging for food. Of note is the albatross which relies on food from the sea to feed chicks. In 2009, images were made public of albatross mothers regurgitating bits of plastic to their young. Artists Susan Middleton and David Liittschwager famously produced images of “Shed Bird,” an albatross chick they encountered while visiting Kure Atoll in 2004. After the chick died unexpectedly, a necropsy revealed a stomach full of colorful plastic, cigarette lighters, bottle caps, clothespins, and toys. These products were collected by the chick’s mother from the ocean, but they start out as ordinary products that humans use and discard in daily life.
There is little information available regarding the origins and pathways of this trash. Increased monitoring and data collection will be useful to better determine geographical distributions thus enabling policy makers to target their management actions and resources. It is difficult to attribute population-level impacts to the prevalence of ocean trash. Further research can identify effective monitoring techniques and help establish standardized methods of assessment.
It is clear that marine debris is a global issue, caused by a global population, and is in need of a global solution. There are few legally binding state-level instruments on marine debris, and even fewer effective enforcement mechanisms. Further, filling knowledge gaps and improving reporting techniques is an expensive process. CMS is committed to taking the necessary steps to help address this problem and looks to its global constituency to help implement the solutions and recommendations. Trash originates across the globe, and so too must solutions.
World Oceans Day was celebrated on 8 June.
Last updated on 26 June 2014