Using citizen science to inventory and map abandoned, lost, or otherwise discarded fishing gear (ALDFG)

A considerable proportion of marine plastic pollution consists of abandoned, lost, or otherwise discarded fishing gear (ALDFG). Whether still intact or break down into fragments, ALDFG is a widespread, enduring problem, and as such, it represents an ideal case for the use of citizen science. The Fish&Click program proposes a mobile application and website to enable non-specialist observers, such as walkers, divers, or sailors, to record their sightings of ALDFG. The simple interface allows the user to characterize found gear without any expert knowledge, and an analysis of these data can shed light on the magnitude and spatio-temporal composition of the ALDFG phenomenon. This report presents the results and feedback from the first two years of Fish&Click, from May 2020 to June 2022, in the north of the Bay of Biscay, Celtic Sea, and English Channel. In addition to a database cleaning procedure, we defined an ad hoc methodology for analyzing these non-standardized data. Using this, we found that the types and quantities of found gear differ between sea and shore locations and were also different from one region to another. We discuss the pros and cons of this citizen-science program, as well as the potential for improvements that might help to mitigate pollution by ALDFG.