Marine debris is one of the most widespread pollution problems facing the global ocean today with millions of tons of debris entering the ocean annually. Marine debris can injure and kill cetaceans through entanglement in, and ingestion of, debris. In a study of marine debris ingestion it was found that 26 species of cetaceans are confirmed to ingest marine debris. A similar study, found that, in the U.S., nine species of cetaceans are confirmed to entangle in marine debris.
The increasing amount of debris in the world's oceans has become a major cause for concern. There are many different types of marine debris. It travels freely and does not recognise national boundaries, which means international collaboration is essential to any attempts to address the issue effectively.
Marine debris ranges from glass, metal, plastics and wood to abandoned or lost fishing gear. Much is synthetic and estimated to endure for up to 600 years. Different materials can threaten cetaceans, and other marine life in different ways. The IWC is working through a number of programmes to understand and mitigate potential threats from a range of different types of debris.
Ingestion of items of debris is another potential threat. Recent research suggested that examples of ingestion have been found for just over half of cetacean species although more work is required to understand better the nature of the threat, the numbers involved and the level of threat at a population level. Perhaps unsurprising given its endurance, plastic is the most commonly detected ingested material recorded.
Microplastics can be ingested directly and also potentially transferred from prey species (krill and copepods) to whales where their accumulation may pose a health threat. As part of its work on pollution, the Scientific Committee is studying the origin, fate and distribution of microplastics.