“Debris ingestion by sea turtles is a global phenomenon of increasing magnitude”

Schuyler, Q., B. D. Hardesty, C. Wilcox & K. Townsend, 2013. Global analysis of anthropogenic debris ingestion by sea turtles. Conservation Biology, open-access, early-view article (free download).

[The authors] “analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011.

Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities.

Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores.

… oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris.

To reduce this risk, anthropogenic debris must be managed at a global level.”

The authors raised several points about debris management:

1. “Standardized reporting methods on debris effects on wildlife, including debris type and size, species, and life-history stage of animals affected, would go a long way toward creating a globally consistent and comparable data set.
2. Increased efforts to understand debris effects in underresearched areas where turtles occur in great numbers (especially Southeast Asia, western and northern Australia, South America, and Africa), and in mid-ocean pelagic turtles would be beneficial.
3. Our results show clearly that debris ingestion by sea turtles is a global phenomenon of increasing magnitude. Our finding that oceanic-stage green and leatherback turtles are at higher risk than benthic-feeding carnivorous turtles means management actions to target these species and life stages should be considered. This is particularly important for leatherback turtles that spend the bulk of their lives in oceanic waters, and are listed as critically endangered (IUCN 2012).
4. Ingestion prevalence at stranding locations was not related to predicted debris density, likely due to the long migrations of turtles. Thus, conducting coastal cleanups will not solve the problem of debris accumulation in the pelagic environment, where animals are most commonly affected, although it is an important step in preventing marine debris input into the ocean.
5. Anthropogenic debris is not only a problem for endangered turtles and other marine wildlife, but also affects human health and safety (e.g., discarded sharps and medical waste and ship encounters with large items). Debris also has aesthetic and economic consequences and may result in decreased tourism (Ballance et al. 2000), reduced economic benefits from fisheries (Havens et al. 2008), and damage to vessels (Jones 1995). Furthermore, debris destroys habitats and aids in the transport of invasive species (Sheavly & Register 2007). It is therefore a high priority to address this global problem.
6. An estimated 80% of debris comes from land-based sources; hence, it is critical to implement effective waste management strategies and to create and maintain a global survey and comprehensive database of marine debris ingestion and entanglement.
7. Additionally, it is worth engaging with industry to create and implement appropriate innovations and controls to assist in decreasing marine debris.”

Photo by Rafn Ingi Finnsson