Conservation

Plastic in the ocean chokes albatrosses

Reviewing: Roman, L., Butcher, R.G., Stewart, D., Hunter, S., Jolly, M., Kowalski, P., Hardesty, B.D. and Lenting, B., 2020. Plastic ingestion is an underestimated cause of death for southern hemisphere albatrosses. Conservation Letters, p.e12785

Grey-headed albatrosses flying over Drake Passage (Wikimedia Commons)

 

Albatrosses are magnificent seabirds. They can live over fifty years, and spend most of their lives flying over the ocean. They can stay over a year at sea without touching down on land, as they sleep while they fly. Their wingspans measure up to 12 feet, which is larger than any other living bird. They can glide over the ocean at up to 70 mph without flapping their wings for several hundred miles. And, sadly, they are at risk of extinction.

 

 

At sea, causes of death for albatrosses include getting entangled in fishing lines and nets and finding less food due to overfishing, which causes fish stocks to decrease. So far, marine plastic has not been recognized as an important threat. Why? Most albatrosses live in the southern hemisphere, where less plastic waste from land enters the ocean relative to the northern hemisphere. Regrettably, as an increasing amount of plastic is thrown out and polluting the ocean, larger amounts of plastic debris have been found floating in areas of the Southern Ocean such as the South Pacific gyre. And when albatrosses feed on plastic pieces, the pieces can tear or block their esophagus, stomach or intestines and result in immediate death. Or the plastic pieces can stay in their stomach, taking up space available for food and causing starvation over time.

Removing a fishing hook from an albatross (Pixnio)
(Rohan Chakravarty, www.greenhumour.com)

 

 

 

 

 

 

 

 

 

 

As ocean plastic is being recognized as a growing problem in the Southern Ocean, a team of scientists decided to assess the risk of marine plastic to albatrosses in the southern hemisphere. Roman and colleagues asked for data on 107 dead albatrosses that were washed onto the beaches in Australia and New Zealand for the last two decades. Experts in veterinary hospitals and pathology services had examined the bodies of these to determine their cause of death when these albatrosses were originally found. The veterinarians found plastic in the digestive systems of 6 albatrosses; plastic had killed three of them by blocking their stomachs. Types of plastic found in these albatross bodies included a rubber ring, a plastic bottle with lid, pieces of rubber latex balloons and a plastic straw. In contrast, the number of deaths caused by feeding on plastic was actually higher than deaths caused by fishing vessels (two). This was a disturbing discovery, because until now, the major cause of albatross death was thought to be their interactions with fishing vessels, and efforts to save albatrosses have been focused on modifying fishing gear and educating the fishing industry.

A Laysan Albatross chick rests on a small derelict fishing net (NOAA Marine Debris Program)

The researchers also collected additional data on the cause of albatross death from other published studies. They included dead albatrosses found from beaches of South Africa and Brazil, or dead birds that were unintentionally caught by fishing vessels. Using this larger dataset, the research team looked into whether the chances of albatrosses dying from feeding on plastic than from getting caught in fishing gear. They found that the former cause of death is as much as – or even more – likely as the latter. This doesn’t mean that fishing gear is less dangerous to albatrosses – it just means that we have been underestimating the danger of marine plastic to albatrosses.

This study raises a red flag by showing that feeding on marine plastic debris is a serious threat to albatrosses. As we continue to dump plastic waste into the ocean, the risk of albatrosses eating plastic is likely to increase. Because albatrosses are long-lived and slow-breeding, it is important that we closely monitor the declining albatross population, and further bring policies that reduce ocean plastic pollution into effect.

 

 

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