seabirds

Keeping Lights On For Turtles

August 8, 2019 By EarthWise Leave a Comment

Gillnets are one of the most common types of fishing gear and are used extensively in most places where people fish for food. They operate by suspending a wall of netting in the water column.

Unfortunately, they are not selective in the species they catch. Sea turtles are one of the most common bycatch species that become entangled in these nets. When turtles are caught in gillnets, they can drown and die. Marine mammals, seabirds, and sharks are also frequently caught in gillnets.

Recently, researchers have been experimenting with illuminating the nets with LED lights to see if increasing net visibility reduces sea turtle bycatch.

Studies in Mexico show green sea turtle bycatch is reduced between 40-60% with no changes in target catch. Studies in Peru show green sea turtle bycatch is reduced between 65-80% with no changes in target catch. Studies in Indonesia show green olive ridley, and hawksbill sea turtle bycatch is reduced by 60% with increases in target catch and catch value.

Recent research shows that net illumination also reduces bycatch of other protected species such as seabirds, sharks and rays, as well as dolphins and porpoises.

The use of illuminated gillnets could prove beneficial to both sea turtles and fisherman by reducing the bycatch that can damage fishing gear.

Studies are now underway off the coast of North Carolina, where state gillnet fisheries are carefully managed to reduce turtle bycatch. Initial studies show that net illumination does not change target catch rates and may even decrease the bycatch of unwanted fish species. When it comes to protecting sea turtles, it looks like a good idea to keep the lights on.

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Illuminated Nets Could Provide A Brighter Future For Sea Turtles

Photo, posted June 2, 2016, courtesy of NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Balloons And Seabirds

March 19, 2019 By EarthWise Leave a Comment

It’s no secret that there is a ton of plastic in the ocean – millions of tons, in fact. Scientists estimate that there is more 165 million tons of plastics swirling about in our oceans today, with an additional 8.8 million tons flowing in every year. As the oceans swell with plastic debris, many marine species wind up ingesting the stuff – often with dire consequences.

All this plastic trash winds up affecting more than just aquatic species, too. According to researchers from the University of Tasmania, a seabird that ingested a single piece of plastic has a 20% chance of mortality. This statistic jumps to 50% if the seabird consumes nine pieces of plastic.

The study, which was recently published in the journal Scientific Reports, also found that while hard plastics account for the majority of plastic debris ingested, it’s far less likely to prove fatal than soft plastics, such as balloons.

In fact, the researchers found that balloons or balloon fragments were the number one marine debris risk of mortality for seabirds, killing almost one in five of the seabirds that ingested them.

The leading cause of death among the seabirds studied was blockage of the gastrointestinal tract. While soft plastics only accounted for 5% of the ingested plastics, they were responsible for more than 40% of seabird mortality. But the researchers make clear that hard plastics were still responsible for more than half of the study’s seabird deaths.

If we want to reduce the number of marine species dying from plastic ingestion, we need to reduce the volume of plastic going into the ocean and do what we can to remove what’s already there.

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