Wicked-Horizon conducted an inspection-survey to assess the extent of floating marine debris, particularly plastic waste, in Eastern Indonesia following the COVID-19 lockdown from June to August 2022. The survey was carried out through visual inspections along the stretch of water from Sorong to Raja Ampad; in the Band Neira area; at Wakatobi; around Komodo National Park; and at North Lombok. Further visual inspections were conducted from North Lombok to Komodo National Park, South Flores, Timor, Saumlakki, Outer Banda Islands, Misool, Raja Ampad, and Sorong from October to November 2022. Based on these large-scale inspections we selected the apparent most polluted area for a quantitate survey.
During the open-sea observations, the most-observed items were single-use plastic bottles, soft drink bags, plastic bags, Styrofoam, and medical protection masks. Polyester and polypropylene ropes lost from boats and the fishing industry were less frequent but significant. However, our observations indicate that most of the plastic waste adrift in Eastern Indonesia originated from households, while boats and the fishing industry contributed to a lesser extent.
Following the initial observations, Wicked Horizon conducted a test sampling survey in the Misool Area utilising a trawling net to obtain quantitative data on the amount, source, and migration pattern of ocean plastic waste. To carry out this survey, a T1 trawling net was rented from OceanKita. The Thomsea’s net is specifically designed for waste collection in harbours, coastal or sheltered waters, and is capable of being towed by a small boat. The filtering socket of the net has a capacity of approximately 40 kg of debris at a density of 0.2. The net is sampling from the surface at a depth of 17 cm, and the collection span of the net is 1 to 3m. The sampling pocket is 0.2 m3 or 200 l, and is capable of catching debris with a length of over 1.7 mm.
When sailing, the net was towed behind the boat at a centred position, which appeared to be the best sampling configuration (M1_2023). However, when using the engine, the propeller wash stirred the debris and pushed it deeper into the water (M3_2023). For this it was necessary to tow the net outside of the boat’s wake (M2_2023). To achieve this, the net was attached with two ropes, one at the side of the boat, the other at the spread-out boom (M4_2023 and M5_2023). With these sampling techniques deployed, the net could be handled easily and sampling was accurate.
The collected sea-debris was brought on board after survey was finished or after the net’s collecting capacity was reached. The net’s contents was subsequently manually separated in the following categories:
• Natural debris that originated from the sea (i.e. seagrass, algee, etc.)
• Natural debris that originated on land (i.e. branches, leaves, coconuts, etc.)
• Plastic debris from industry and fishery (i.e. ropes, nets, foam containers, etc.)
• Plastic debris from households (i.e. drink bottles, plastic bags, food packages, etc.)
• Other debris of human activity of unknown origin
We like to thank the Misool Foundation for their motivation for this study and their rangers for help with the logistics. We would also like to thank OceanKita for renting the Thomsea’s 1T net at a reduced price.
Special thanks goes to the crew of SY Nora, a group of students from the Kristiansand Folk Highschool that worked as volunteers during all five Misool 2023 data collections.
This research was founded by Wicked Horizon AS.