Pacific Whale Foundation Study on Marine Debris
Highlights Need for Enhanced Policies and Local Monitoring
Plastic bags consistently rank as one of the top marine debris items worldwide. A recent study by Pacific Whale Foundation (PWF) reports that no plastic bags were collected during a 15-month collection period, highlighting the impact of effective local marine debris policies and monitoring. The study was published in April 2016, Volume 105 of Marine Pollution Bulletin.
“Currently there is little data that evaluates the actual success of marine debris policies,” said Lauren Blickley, the study’s lead author. “We need to know where debris is coming from and which debris items are most common in order to create successful policies. Our goal with this research was to use debris data to better inform local efforts.”
Hawaii has been at the forefront of marine debris policy, recently becoming the first state to ban single-use plastic bags. The state has also implemented initiatives to reduce cigarette butt litter (the most commonly littered item in the environment) by prohibiting the use of tobacco products at all state beaches and county beaches on Maui, Oahu, and Hawaii Island.
PWF researchers collected and compared samples of debris loads at three different sites on Maui, determined environmental factors that significantly influence debris accumulation, and identified the most common debris items.
Maui’s north shore (windward) site received the largest debris loads, where the most common debris items were hard plastic fragments and ocean-based debris such as nylon fishing net/rope, oyster spacer tubes, and fishing line. Leeward study sites on Maui’s south and west shorelines saw a greater prevalence of land-based debris, most notably cigarette butts.
The researchers were able to determine that ocean-based debris is a much more significant contributor to Maui’s local debris loads than items that may be left behind by beachgoers. “This doesn’t mean that we should abandon local efforts,” said Blickley, “but it does highlight the need to initiate marine debris conversations on an ocean-wide scale.”
The PWF study also found debris to be accumulating at a much higher rate than previously thought. “The vast majority of shoreline marine debris studies sample once per month,” said Blickley. “We sampled daily and found that debris accumulation depends significantly on variations in wind and tides. Monthly surveys can’t capture these daily extremes.”
Researchers collected 30 times the amount of trash when sampling was conducted on a daily versus monthly basis. On calm days, as few as 20 pieces of trash could be collected at a site, whereas an increase in wind could result in collecting over 1,000 debris items at the same beach a mere 24 hours later. These results indicate that monthly surveys are likely underestimating marine debris loads and the rate of debris turnover.
“Marine debris is a really dynamic beast,” noted Blickley. “It is not a one-size-fits-all problem, so local data is the only way to ensure that we are effectively targeting the biggest debris culprits." Ultimately, the research highlights the need to keep debris, particularly plastics, from reaching the ocean, lakes and streams in the first place.
"Marine debris poses a significant threat to marine life and coral reef ecosystems," stated PWF Founder and Executive Director, Greg Kaufman. "To solve the issue, a holistic approach is needed that combines enhanced industry standards, better waste management, and improved public awareness."
Pacific Whale Foundation is a non-profit organization based on Maui dedicated to protecting whales and our oceans through science and advocacy. For more information on PWF research, education and conservation programs, please visitwww.pacificwhale.org.