Unique experiment to test modern mapping tools on ghost nets

One of the critical challenges of the project is to identify more cost-efficient techniques – enabling more environmentally friendly, smoother and more accurate ways to detect and locate lost fishing gears. One potential way is to use hydro-acoustic surveying. E.g. side-scan sonars are today used in a wide range of different surveys, but the question is – can it detect lost fishing gears?

To explore this option further, MARELITT Baltic has designed an experiment by deploying two authentic ghost net fleets in coastal waters NNE of Simrishamn. These 400 m long net fleets were retrieved earlier this year during cleaning actions within the project. The nets have been stored specifically to maintain their authenticity. In other words, they are still covered with algae, containing plastic objects, dead fish, some sections are totally twisted whereas others have netting bundles or sheets sticking out from the fleets and even up from the seabed etc.

These two ghost net fleets are typical for areas along the Swedish coastline with more rockier and topographically more varying seabed. The net fleets are deployed on two types of seabed typical for actively used gillnet fishing grounds along the west coast of southern Baltic Sea. The fleets are deliberately located close to coast line to secure good weather conditions, which logically results in less typical water depth (for gillnetting it is 40-60m).

Through this experiment, we offer you and your institute a chance to test your hydro-acoustic instrument on two verified and authentic objects. You are free to enter the area and test as many equipment as you prefer and collect data. The fleets are anchored and are planned for use the first week in September. If you wish to test your gear, please contact:

Vesa Tschernij, project manager, 0414-819166 or vesa.tschernij@simrishamn.se
Camilla Witt, project assistant, 0414-819168 or camilla.witt@simrishamn.se

The experiment will end with a workshop for experts only
Regardless if you have visited our experimental site and have some results (e.g. side-scan sonar or other type of images) or not, we would like to invite you to a workshop which we arrange in Marine center, Simrishamn September the 6th starting at 10.00. The aim of the workshop is, by using your former experience and perhaps your results from our experiment, to evaluate the outcome and hopefully draw up some achievable future milestones.

By inviting experts and keeping the meeting reasonable small (max. around 10 people), we hope to have a detailed and fruitful discussion on the critical issues concerning future use of hydro-acoustic as a survey technology.

We are also very happy and honored to have with us an experienced side-scan specialist Crayton Fenn from USA (www.fennent.com) who will bring his ghost-net-optimized survey gear.

Read more about the possible use of sonars in the Prestudy on Sonar Transponder.