Estimating recreational fishing fleet using satellite data in the Aegean and Ionian Seas (Mediterranean Sea)

In the Mediterranean Sea, recreational fishing is part of the local culture and has been practiced for centuries using various techniques and gears. Yet, recreational fishing effort and catches are not officially recorded in most Mediterranean countries, Greece included. The objective of this work was to estimate the number of vessels fishing for recreational purposes in the Aegean and Ionian Seas (Greece) using two independent sources of data. Firstly, we physically visited 42 ports and marinas across the Greek Aegean Sea coastline and counted the recreational vessels. Secondly, we used satellite image frames (from Google Earth) to count the recreational vessels at the same and in additional 620 ports and marinas of the entire Aegean (420 ports) and Ionian (200 ports) coastlines, including the inhabited islands. The agreement between the in situ visits and the satellite data was very high (correlation coefficient r = 0.96, P < 0.001), indicating that Google Earth is a valuable and low cost tool that provides useful information for fisheries management. According to the satellite data, the total number of recreational fishing vessels was about 24,650 in the 462 ports of the Aegean Sea and 7000 in the 200 ports of the Ionian Sea; this adds up to a total number of around 31,650 recreational fishing vessels in Greek waters, which agrees with the number of recreational fishing licenses issued in 2014 but is lower compared to previous estimates. Most vessels were recorded near large cities, where the majority of inhabitants are concentrated and in islands, where the majority of tourists spend their time.