NOAA's Marine Debris Blog

Keepin' the Sea Free of Debris!

The Need to Quantify

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I spent about half an hour staring off the side of the ship yesterday; saw one possible piece of line, about a foot long. But honestly, it could have been plant material. Nothing else. And then today I spent another 45 minutes or so. I did see the knot end of a yellow balloon and a plastic handle of some sort. Other than that, it was lots of feathers, doubtless coming from the tens of birds flying along with and around us. The viewing conditions were pretty much perfect, as this photo from yesterday shows.

I wonder when we’ll have enough information to be able to understand the amount and movement of marine debris in the oceans. It’s odd that in a place like Hawaii, which we know is so heavily affected by marine debris, the ocean looks so clean and clear. Maybe it all comes in during winter storms, like most of it does in my hometown on the windward side of Oahu. Or maybe it’s just patchy. Marie was telling me that she’s never seen as much debris on these cruises to the Northwestern Hawaiian Islands (NWHI) as she did on last spring’s at-sea detection cruise that headed straight north from Oahu to about 36 degrees north latitude. For reference, the northernmost atoll in the NWHI is at about 28.5 degrees north.

We struggle so much with numbers. Some of it is just human nature to name and quantify so we can understand. But some of it is a real need because that information is important in developing policy and deciding how to “manage” the debris. If we don’t know the size or source of the problem, how can we convince those who fund us that this is the best way to attack the problem? We have to have a business case, even one that involves corals and monk seals. On the one hand, it’s true that it’s just not right that manmade materials are ubiquitous in areas far from man’s activities. But without solid information on amount and impacts, how can we convince folks that THIS problem is more important than the scores or hundreds of others competing for limited attention and resources?

Kyle, Marie, and I were talking after lunch about all the data that have been collected during the cruises to remove debris in the NWHI. One estimate, based on those data, was that 52 metric tons land in the NWHI every year. We talked about how we could refine or recalculate an accumulation rate but also about many other research needs we have. Why does derelict net hang up in certain areas and not in others? Kyle has been doing this for nine years, and he has a gut feeling for where the nets will be. Is this something we can quantify just in case there comes a time when Kyle can’t lead us there? How do the areas of high accumulation compare to weather, ENSO cycles (El Nino/Southern Oscillation), currents, and winds? How does the bathymetry and relief affect accumulation? Shallow reticulated coral areas, like Pearl and Hermes Atoll and Maro Reef, are the areas that the marine debris crew have observed to have the lion’s share of nets.

Tomorrow morning we arrive at French Frigate Shoals and will be out on the shorelines and in the water. I feel sure that what we experience will trigger more discussions. I’ll keep you posted.

Author: NOAA Marine Debris Program

The NOAA Marine Debris Program envisions the global ocean and its coasts, users, and inhabitants free from the impacts of marine debris. Our mission is to investigate and solve the problems that stem from marine debris, in order to protect and conserve our nation's marine environment, natural resources, industries, economy, and people.

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